Piezoelectric actuator, liquid discharge head, and recording device

Abstract

Disclosed is a piezoelectric actuator which comprises a piezoelectric element that is deformed by the application of a voltage. The piezoelectric element comprises a piezoelectric ceramic body and an electrode that applies a voltage to the piezoelectric ceramic body. The electrode comprises metal oxides and a base material that contains a noble metal, and the metal oxides are scattered inside the base material.

Description

Technical Field

[0001] Embodiments of the disclosure relate to a piezoelectric actuator, a liquid discharge head, and a recording apparatus.

Background Art

[0002] As printing apparatuses, inkjet printers and inkjet plotters using an inkjet recording method are known. Such an inkjet printing apparatus is equipped with a liquid discharge head for discharging liquid.

[0003] The liquid discharge head discharges the liquid in a pressurizing chamber from a nozzle by driving a piezoelectric element located above the pressurizing chamber to change the pressure inside the pressurizing chamber. The piezoelectric element includes a piezoelectric ceramic body and an electrode that applies voltage to the piezoelectric ceramic body.

[0004] When voltage is applied to the piezoelectric ceramic body, domains in the piezoelectric ceramic body move such that the c-axis of the domains aligns with the direction of the electric field inside the piezoelectric ceramic body, thereby displacing the piezoelectric ceramic body and generating a driving force.

Prior Art Literature

Patent Literature

[0005]

Patent Literature 1

Summary of the Invention

[0006] The piezoelectric actuator of the present disclosure includes a piezoelectric element that deforms when voltage is applied thereto. The piezoelectric element includes a piezoelectric ceramic body and an electrode that applies voltage to the piezoelectric ceramic body. The electrode includes a base material containing a noble metal and a metal oxide, and the metal oxide is scattered inside the base material.

Brief Description of Drawings

[0007] [Figure 1] Figure 1 is a schematic side view of a printer according to this embodiment. [Figure 2] Figure 2 is a schematic plan view of the printer according to this embodiment. [Figure 3] Figure 3 is a schematic exploded perspective view of the liquid dispensing head according to this embodiment. [Figure 4] Figure 4 is an enlarged plan view of the head body according to the embodiment. [Figure 5] Figure 5 is an enlarged view of the area enclosed by the dashed line shown in Figure 4. [Figure 6] Figure 6 is a cross-sectional view taken along the line VI-VI shown in Figure 4. [Figure 7] Figure 7 shows an SEM image of the cross-sectional state of the surface electrode in Example 1. [Figure 8] Figure 8 shows an SEM image of the cross-sectional state of the surface electrode in Example 3. [Figure 9] Figure 9 shows an SEM image of the cross-sectional state of the surface electrode in Example 5. [Figure 10] Figure 10 shows an SEM image of the cross-sectional state of the surface electrode in Reference Example 2. [Figure 11] Figure 11 shows the relationship between the surface electrode's firing temperature and the area ratio of metal oxides within the electrode and at the interface of the surface electrode. [Figure 12] Figure 12 shows the relationship between the surface electrode's firing temperature and the area ratio of the metal oxide within the electrode to the metal oxide at the surface electrode interface. [Figure 13] Figure 13 shows an SEM image of the surface state of the surface electrode in Example 1. [Figure 14] Figure 14 shows an SEM image of the surface state of the surface electrode in Example 3. [Figure 15] Figure 15 shows an SEM image of the surface state of the surface electrode in Example 5. [Figure 16] Figure 16 shows an SEM image of the surface state of the surface electrode in Reference Example 2. [Figure 17]FIG. 17 is a diagram showing the relationship between the baking temperature of a surface electrode and the area ratio of metal oxide on the surface of the surface electrode. [Figure 18] FIG. 18 is a diagram showing the relationship between the baking temperature of a surface electrode and the coercive electric field of a piezoelectric element. [Figure 19] FIG. 19 is a diagram showing the transition of driving deterioration between the piezoelectric element of Example 3 and the piezoelectric element of Reference Example 1. DESCRIPTION OF EMBODIMENTS

[0008] Hereinafter, embodiments of a piezoelectric actuator, a liquid discharge head, and a recording apparatus disclosed in the present application will be described. It should be noted that the present disclosure is not limited by the embodiments shown below.

[0009] As printing apparatuses, inkjet printers and inkjet plotters using an inkjet recording method are known. Such an inkjet printing apparatus is equipped with a liquid discharge head for discharging liquid.

[0010] The liquid discharge head discharges liquid in a pressurizing chamber from a nozzle by driving a piezoelectric element positioned above the pressurizing chamber to change the pressure in the pressurizing chamber. The piezoelectric element includes a piezoelectric ceramic body and an electrode that applies a voltage to the piezoelectric ceramic body.

[0011] When a voltage is applied to the piezoelectric ceramic body, domains in the piezoelectric ceramic body move such that the c-axis thereof is oriented in the direction of the electric field, which displaces the piezoelectric ceramic body and generates a driving force.

[0012] However, in the above-described conventional technology, when the piezoelectric element is continuously driven, a phenomenon in which domains are gradually fixed inside the piezoelectric ceramic body may occur. This gradually reduces the displacement amount of the piezoelectric element, and thus there is a risk that a desired driving amount cannot be obtained with the piezoelectric element.

[0013] Accordingly, there is a demand for realizing a technology that solves the above problems and can reduce driving deterioration of piezoelectric elements.

[0014] <Configuration of Printer> First, an overview of a printer 1, which is an example of a recording apparatus according to an embodiment, will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic side view of the printer 1 according to the embodiment. FIG. 2 is a schematic plan view of the printer 1 according to the embodiment. The printer 1 according to the embodiment is, for example, a color inkjet printer.

[0015] As shown in FIG. 1, the printer 1 includes a paper feed roller 2, a guide roller 3, a coating device 4, a head case 5, a plurality of conveying rollers 6, a plurality of frames 7, a plurality of liquid discharge heads 8, a conveying roller 9, a dryer 10, a conveying roller 11, a sensor unit 12, and a collecting roller 13.

[0016] Further, the printer 1 includes a control unit 14 that controls each section of the printer 1. The control unit 14 controls operations of the paper feed roller 2, the guide roller 3, the coating device 4, the head case 5, the plurality of conveying rollers 6, the plurality of frames 7, the plurality of liquid discharge heads 8, the conveying roller 9, the dryer 10, the conveying roller 11, the sensor unit 12, and the collecting roller 13.

[0017] The printer 1 records images and characters on a recording medium P by causing droplets to land on the recording medium P. The recording medium P is, for example, paper. The recording medium P is not limited thereto, and may be cloth or the like. Before use, the recording medium P is in a state wound around the paper feed roller 2. The printer 1 conveys the recording medium P wound around the paper feed roller 2 into the head case 5 via the guide roller 3 and the coating device 4.

[0018] The coating device 4 uniformly applies a coating agent to the recording medium P. Since this allows surface treatment to be performed on the recording medium P, the print quality of the printer 1 can be improved.

[0019] The head case 5 houses multiple transport rollers 6, multiple frames 7, and multiple liquid discharge heads 8. Inside the head case 5, a space is formed that is isolated from the outside, except for some parts such as the area where the recording medium P enters and exits.

[0020] The internal space of the head case 5 is controlled by the control unit 14, as needed, by at least one of the control factors such as temperature, humidity, and atmospheric pressure. The transport rollers 6 transport the recording medium P to the vicinity of the liquid discharge head 8 inside the head case 5.

[0021] The frame 7 is a rectangular flat plate and is positioned close above the recording medium P that is transported by the transport rollers 6. Also, as shown in Figure 2, the frame 7 is positioned so that its longitudinal direction is perpendicular to the transport direction of the recording medium P. Inside the head case 5, multiple (for example, four) frames 7 are positioned at predetermined intervals along the transport direction of the recording medium P.

[0022] In the following explanation, the transport direction of the recording medium P may be referred to as the "sub-scanning direction," and the direction perpendicular to this sub-scanning direction and parallel to the recording medium P may be referred to as the "main scanning direction."

[0023] The liquid ejection head 8 is supplied with a liquid, such as ink, from a liquid tank (not shown). The liquid ejection head 8 ejects the liquid supplied from the liquid tank.

[0024] The control unit 14 controls the liquid ejection head 8 based on data such as images and characters, and ejects liquid toward the recording medium P. The distance between the liquid ejection head 8 and the recording medium P is, for example, about 0.5 to 20 mm.

[0025] The liquid dispensing head 8 is fixed to the frame 7. The liquid dispensing head 8 is positioned so that its longitudinal direction is perpendicular to the transport direction of the recording medium P.

[0026] In other words, the printer 1 according to this embodiment is a so-called line printer in which a liquid ejection head 8 is fixed inside the printer 1. However, the printer 1 according to this embodiment is not limited to a line printer, and may be a so-called serial printer.

[0027] A serial printer is a type of printer that alternately performs the operation of recording while moving a liquid ejection head 8 back and forth in a direction intersecting the transport direction of the recording medium P, for example, in a direction approximately perpendicular to the transport direction of the recording medium P, and transporting the recording medium P.

[0028] As shown in Figure 2, multiple (for example, five) liquid discharge heads 8 are fixed to a single frame 7. Figure 2 shows an example where three liquid discharge heads 8 are located in front of the recording medium P in the transport direction and two are located behind it, and the liquid discharge heads 8 are positioned so that the centers of each liquid discharge head 8 do not overlap in the transport direction of the recording medium P.

[0029] A head group 8A is formed by multiple liquid ejection heads 8 located on a single frame 7. The four head groups 8A are positioned along the transport direction of the recording medium P. Liquid ejection heads 8 belonging to the same head group 8A are supplied with ink of the same color. As a result, the printer 1 can perform printing with four colors of ink using the four head groups 8A.

[0030] The ink colors ejected from each head group 8A are, for example, magenta (M), yellow (Y), cyan (C), and black (K). The control unit 14 controls each head group 8A to eject multiple colors of ink onto the recording medium P, thereby printing a color image onto the recording medium P.

[0031] Furthermore, in order to treat the surface of the recording medium P, a coating agent may be discharged onto the recording medium P from the liquid discharge head 8.

[0032] Furthermore, the number of liquid ejection heads 8 included in one head group 8A, and the number of head groups 8A installed in printer 1, can be changed as appropriate depending on the object to be printed and the printing conditions. For example, if the color to be printed on the recording medium P is a single color, and the printing is limited to the area that can be printed with one liquid ejection head 8, then printer 1 may only have one liquid ejection head 8.

[0033] The recording medium P, which has been printed inside the head case 5, is transported to the outside of the head case 5 by the transport roller 9 and passes through the inside of the dryer 10. The dryer 10 dries the printed recording medium P. The recording medium P that has been dried in the dryer 10 is transported by the transport roller 11 and collected by the recovery roller 13.

[0034] In printer 1, drying the recording medium P in the dryer 10 reduces the likelihood of overlapping recording medium P P sticking together or friction caused by undried liquid in the recovery roller 13.

[0035] The sensor unit 12 is composed of position sensors, speed sensors, temperature sensors, and the like. The control unit 14 can determine the state of each part of the printer 1 based on the information from the sensor unit 12 and control each part of the printer 1.

[0036] The printer 1 described so far has shown the case where the recording medium P is used as the printing target (i.e., the recording medium), but the printing target in printer 1 is not limited to the recording medium P; a roll of cloth or other material may also be used as the printing target.

[0037] Alternatively, the printer 1 may transport the recording medium P on a transport belt instead of directly transporting it. By using a transport belt, the printer 1 can print on sheets of paper, cut cloth, wood, tiles, etc.

[0038] The printer 1 may also print wiring patterns for electronic devices by ejecting a liquid containing conductive particles from the liquid ejection head 8. Alternatively, the printer 1 may produce chemical products by ejecting a predetermined amount of liquid chemical agent or a liquid containing a chemical agent from the liquid ejection head 8 toward a reaction vessel or the like.

[0039] <Configuration of the liquid dispensing head> Next, the configuration of the liquid dispensing head 8 according to the embodiment will be described with reference to Figure 3. Figure 3 is a schematic exploded perspective view of the liquid dispensing head 8 according to the embodiment.

[0040] The liquid discharge head 8 comprises a head body 20, a wiring section 30, a housing 40, and a pair of heat sinks 45. The head body 20 includes a flow path member 21, a piezoelectric actuator substrate 22 (see Figure 4), and a reservoir 23.

[0041] In the following explanation, for convenience, the direction in which the head body 20 is provided in the liquid discharge head 8 may be referred to as "down," and the direction in which the housing 40 is provided relative to the head body 20 may be referred to as "up."

[0042] The flow path member 21 of the head body 20 is substantially flat in shape and has a first surface 21a (see Figure 6), which is a main surface, and a second surface 21b (see Figure 6), which is located on the opposite side of the first surface 21a. The first surface 21a has an opening (not shown), and liquid is supplied into the interior of the flow path member 21 from a reservoir 23, which will be described later, through this opening.

[0043] The second surface 21b has multiple discharge holes 63 (see Figure 6) for discharging liquid onto the recording medium P. In other words, the second surface 21b is the nozzle surface of the head body 20. The flow path member 21 has a flow path inside that allows liquid to flow from the first surface 21a to the second surface 21b. The discharge holes 63 are an example of nozzles.

[0044] The piezoelectric actuator substrate 22 is located on the first surface 21a of the flow channel member 21. The piezoelectric actuator substrate 22 has a plurality of piezoelectric elements 70 (see Figure 6). The flexible substrate 31 of the wiring section 30 is electrically connected to the piezoelectric actuator substrate 22. The configuration of the piezoelectric actuator substrate 22 will be described later with reference to Figures 4 to 6.

[0045] A reservoir 23 is located on the piezoelectric actuator substrate 22. Specifically, the reservoir 23 is located on the first surface 21a of the flow channel member 21 so as to cover the piezoelectric actuator substrate 22.

[0046] The reservoir 23 supplies liquid to the pressurized chamber 62 of the flow channel member 21, which will be described later. Specifically, the reservoir 23 has openings 23a at both ends in the longitudinal direction. The reservoir 23 has a flow channel inside, and liquid is supplied from the outside through the openings 23a. The reservoir 23 has the function of supplying liquid to the pressurized chamber 62 of the flow channel member 21, and the function of storing the supplied liquid.

[0047] The wiring section 30 includes a flexible substrate 31, a head substrate 32, a driver IC 33, a pressing member 34, and an elastic member 35. The flexible substrate 31 has the function of transmitting a predetermined signal sent from the outside to the head body 20. As shown in Figure 3, the liquid discharge head 8 according to this embodiment has two flexible substrates 31.

[0048] One end of the flexible circuit board 31 is electrically connected to the piezoelectric actuator circuit board 22 of the head body 20. The other end of the flexible circuit board 31 is extended upward to pass through the opening 23b of the reservoir 23 and is electrically connected to the head circuit board 32.

[0049] This allows the piezoelectric actuator substrate 22 of the head body 20 to be electrically connected to the outside. The flexible substrate 31 is, for example, a film-like substrate (COF) made of polyimide, and a driver IC 33 and the like are mounted on the substrate.

[0050] The head board 32 is located above the head body 20. The head board 32 has the function of distributing signals to the driver IC 33. The driver IC 33 is provided on one main surface of the flexible board 31. Based on the signals sent from the control unit 14 (see Figure 1), the driver IC 33 drives the piezoelectric actuator board 22 of the head body 20. In this way, the driver IC 33 drives the liquid dispensing head 8.

[0051] The pressing member 34 has a roughly U-shape in cross-section and presses the driver IC 33 on the flexible substrate 31 from the inside toward the heat sink 45. In this embodiment, the heat generated when the driver IC 33 is driven can be efficiently dissipated to the outer heat sink 45.

[0052] The elastic member 35 is positioned so as to be in contact with the outer wall of a pressing portion (not shown) of the pressing member 34. By providing such an elastic member 35, the possibility of the pressing member 34 damaging the flexible substrate 31 when pressing the driver IC 33 can be reduced.

[0053] The elastic member 35 is made of, for example, foam double-sided tape. Furthermore, by using, for example, a non-silicon thermal conductive sheet as the elastic member 35, the heat dissipation of the driver IC 33 can be improved. Note that the elastic member 35 is not necessarily required.

[0054] The housing 40 is positioned on the head body 20 so as to cover the wiring section 30. This allows the housing 40 to seal the wiring section 30. The housing 40 is made of, for example, resin or metal.

[0055] The housing 40 is box-shaped and extends long in the main scanning direction, and has a first opening 40a and a second opening 40b on a pair of opposing sides along the main scanning direction. The housing 40 also has a third opening 40c on its bottom surface and a fourth opening 40d on its top surface.

[0056] One side of the heat sink 45 is positioned to block the first opening 40a, and the other side of the heat sink 45 is positioned to block the second opening 40b.

[0057] The heat sink 45 is provided so as to extend in the main scanning direction and is made of a metal or alloy with high heat dissipation properties. The heat sink 45 is provided so as to be in contact with the driver IC 33 and dissipates the heat generated by the driver IC 33.

[0058] The pair of heat sinks 45 are each fixed to the housing 40 by screws (not shown). As a result, the housing 40 to which the heat sinks 45 are fixed has a box shape with the first opening 40a and the second opening 40b closed, and the third opening 40c and the fourth opening 40d open.

[0059] The third opening 40c is positioned opposite the reservoir 23. The flexible substrate 31 and the pressing member 34 are inserted through the third opening 40c.

[0060] The fourth opening 40d is provided for inserting a connector (not shown) provided on the head board 32. Sealing the space between this connector and the fourth opening 40d with resin or the like makes it difficult for liquids, dust, etc. to enter the inside of the housing 40.

[0061] Furthermore, the housing 40 has a heat insulating section 40e. This heat insulating section 40e is positioned adjacent to the first opening 40a and the second opening 40b, and is provided to protrude outward from the side surface of the housing 40 along the main scanning direction.

[0062] The heat-insulating section 40e is formed to extend in the main scanning direction. That is, the heat-insulating section 40e is located between the heat sink 45 and the head body 20. By providing the heat-insulating section 40e in the housing 40 in this way, heat generated by the driver IC 33 is less likely to be transferred to the head body 20 via the heat sink 45.

[0063] Note that the configuration of the liquid dispensing head 8 shown in Figure 3 is merely an example, and the configuration of the liquid dispensing head 8 is not limited to the configuration shown in Figure 3.

[0064] <Construction of the head unit> Next, the configuration of the head body 20 according to the embodiment will be described with reference to Figures 4 to 6. Figure 4 is an enlarged plan view of the head body 20 according to the embodiment. Figure 5 is an enlarged view of the region V enclosed by the dashed line shown in Figure 4. Figure 6 is a cross-sectional view taken along the line VI-VI shown in Figure 4.

[0065] As shown in Figure 4, the head body 20 has a flow path member 21 and a piezoelectric actuator substrate 22. The flow path member 21 has a supply manifold 61, a plurality of pressurized chambers 62 and a plurality of discharge holes 63.

[0066] Multiple pressurized chambers 62 are connected to a supply manifold 61. Multiple discharge ports 63 are each connected to one of the pressurized chambers 62.

[0067] The pressurized chamber 62 opens onto the first surface 21a (see Figure 6) of the flow channel member 21. The first surface 21a of the flow channel member 21 also has an opening 61a that connects to the supply manifold 61. Liquid is supplied from the reservoir 23 (see Figure 2) to the interior of the flow channel member 21 through the opening 61a.

[0068] In the example shown in Figure 4, the head body 20 has four supply manifolds 61 inside the flow channel member 21. The supply manifolds 61 have an elongated shape that extends along the longitudinal direction (i.e., the main scanning direction) of the flow channel member 21, and openings 61a of the supply manifolds 61 are formed at both ends on the first surface 21a of the flow channel member 21.

[0069] Multiple pressurized chambers 62 are formed in the flow channel member 21, extending two-dimensionally. As shown in Figure 5, the pressurized chambers 62 are hollow regions having a roughly rhomboid planar shape with rounded corners, for example. The shape of the pressurized chambers 62 is not limited to the illustrated example. The pressurized chambers 62 open to the first surface 21a of the flow channel member 21 and are closed by the piezoelectric actuator substrate 22 being joined to the first surface 21a.

[0070] The pressurized chambers 62 form rows of pressurized chambers arranged in the longitudinal direction. The pressurized chambers 62 in a row of pressurized chambers are positioned in a staggered manner between two adjacent rows of pressurized chambers. Four rows of pressurized chambers connected to one supply manifold 61 constitute one group of pressurized chambers. In the example shown in Figure 4, there are four groups of pressurized chambers through which the flow path member 21 is connected.

[0071] Furthermore, the relative arrangement of the pressurized chambers 62 within each pressurized chamber group is the same, and each pressurized chamber group is slightly offset in the longitudinal direction.

[0072] The discharge hole 63 is located in a position that avoids the region of the flow path member 21 that faces the supply manifold 61. In other words, when the flow path member 21 is viewed through from the first surface 21a side, the discharge hole 63 does not overlap with the supply manifold 61.

[0073] Furthermore, in a plan view, the ejection holes 63 are positioned to fit within the mounting area of ​​the piezoelectric actuator substrate 22. These ejection holes 63 occupy an area of ​​approximately the same size and shape as the piezoelectric actuator substrate 22 as a single group.

[0074] In the liquid discharge head 8, the driver IC 33 displaces the piezoelectric element 70 (see Figure 6) of the piezoelectric actuator substrate 22 based on a signal sent from the control unit 14 (see Figure 1). As a result, the pressurized chamber 62 is pressurized and the liquid inside the pressurized chamber 62 is discharged from the discharge hole 63.

[0075] As shown in Figure 6, the flow channel member 21 has a laminated structure in which multiple plates are stacked. For example, the flow channel member 21 has, in order from the top surface, a cavity plate 21A, a base plate 21B, an aperture plate 21C, a supply plate 21D, manifold plates 21E, 21F, 21G, a cover plate 21H, and a nozzle plate 21I.

[0076] The plates have numerous holes formed in them. The thickness of the plates is approximately 10 μm to 300 μm. This allows for high precision in hole formation. The plates are stacked in a aligned manner so that these holes communicate with each other to form predetermined flow channels.

[0077] In the flow channel member 21, the supply manifold 61 and the discharge hole 63 are connected by individual flow channels 64. The supply manifold 61 is located on the second surface 21b side inside the flow channel member 21, and the discharge hole 63 is located on the second surface 21b of the flow channel member 21.

[0078] The individual flow path 64 has a pressurizing chamber 62 and an individual supply flow path 65. The pressurizing chamber 62 is located on the first surface 21a of the flow path member 21, and the individual supply flow path 65 is a flow path connecting the supply manifold 61 and the pressurizing chamber 62.

[0079] Furthermore, the individual supply channel 65 includes a narrower constriction 66 than the rest of the channel. Because the constriction 66 is narrower than the rest of the individual supply channel 65, it has high flow resistance. Thus, when the flow resistance of the constriction 66 is high, the pressure generated in the pressurizing chamber 62 does not easily escape to the supply manifold 61.

[0080] The piezoelectric actuator substrate 22 includes piezoelectric ceramic layers 22A and 22B, an internal electrode 71, a surface electrode 72, a connecting electrode 73, a dummy connecting electrode 74, and a surface electrode 75 (see Figure 4). The piezoelectric ceramic layer 22A is an example of a piezoelectric ceramic body, and the surface electrode 72 is an example of an electrode.

[0081] The piezoelectric ceramic layer 22B, the internal electrode 71, the piezoelectric ceramic layer 22A, and the surface electrode 72 are stacked in this order from bottom to top, that is, from the flow channel member 21 side.

[0082] The piezoelectric ceramic layers 22A and 22B both extend on the first surface 21a of the flow channel member 21 so as to span multiple pressurized chambers 62. Each of the piezoelectric ceramic layers 22A and 22B has a thickness of approximately 20 μm. The piezoelectric ceramic layers 22A and 22B are composed of, for example, a ferroelectric lead zirconate titanate (PZT)-based ceramic material.

[0083] The internal electrode 71 is formed over substantially the entire surface in the planar direction in the region between the piezoelectric ceramic layer 22A and the piezoelectric ceramic layer 22B. That is, the internal electrode 71 overlaps with all the pressurized chambers 62 in the region facing the piezoelectric actuator substrate 22.

[0084] The thickness of the internal electrode 71 is approximately 2 μm. The internal electrode 71 is made of a metallic material such as an Ag-Pd system.

[0085] The surface electrode 72 includes a main electrode 72a and an extraction electrode 72b. The main electrode 72a is located on the piezoelectric ceramic layer 22A in the region facing the pressurizing chamber 62. The main electrode 72a is slightly smaller than the pressurizing chamber 62 and has a shape that is approximately similar to that of the pressurizing chamber 62.

[0086] The extraction electrode 72b is drawn out from the main electrode 72a to the area opposite the pressurizing chamber 62. The surface electrode 72 is constructed using a precious metal material such as Au or Ag as the base material. Details of this surface electrode 72 will be described later.

[0087] The connecting electrode 73 is located on the extraction electrode 72b and is formed in a convex shape with a thickness of approximately 15 μm. The connecting electrode 73 is also electrically connected to an electrode provided on the flexible substrate 31 (see Figure 3). The connecting electrode 73 is made of, for example, silver-palladium containing glass frit.

[0088] The dummy connection electrode 74 is connected to the piezoelectric ceramic layer 22 A It is positioned above and is positioned so as not to overlap with various electrodes such as the surface electrode 72. The dummy connection electrode 74 connects the piezoelectric actuator substrate 22 and the flexible substrate 31, increasing the connection strength.

[0089] Furthermore, the dummy connection electrode 74 is connected to the piezoelectric actuator substrate 22, Flexible substrate 31 The distribution of contact points is made uniform, and the electrical connection is stabilized. The dummy connection electrode 74 is preferably made of the same material as the connection electrode 73 and is preferably formed using the same process as the connection electrode 73.

[0090] The surface electrode 75 shown in Figure 4 is a piezoelectric ceramic layer 22 A The surface electrode 75 is formed in a position that avoids the surface electrode 72. The surface electrode 75 is connected to the internal electrode 71 via a via hole formed in the piezoelectric ceramic layer 22A.

[0091] As a result, the surface electrode 75 is grounded and maintained at ground potential. The surface electrode 75 may be made of the same material as the surface electrode 72 and may be formed using the same process as the surface electrode 72.

[0092] Multiple surface electrodes 72 are individually electrically connected to a control unit 14 (see Figure 1) via a flexible substrate 31 and wiring in order to control their potential individually. When the surface electrodes 72 and the internal electrodes 71 are set to different potentials and an electric field is applied in the polarization direction of the piezoelectric ceramic layer 22A, the portion of the piezoelectric ceramic layer 22A to which the electric field is applied acts as an active part that is distorted by the piezoelectric effect.

[0093] In other words, in the piezoelectric actuator substrate 22, the surface electrode 72, the piezoelectric ceramic layer 22A, and the portion of the internal electrode 71 facing the pressurized chamber 62 function as a piezoelectric element 70.

[0094] Then, as the piezoelectric element 70 undergoes unimorph deformation, the pressurized chamber 62 is pressed, and droplets are discharged from the discharge port 63.

[0095] Here, the driving procedure for the liquid discharge head 8 according to the embodiment will be described. The surface electrode 72 is initially set to a higher potential than the internal electrode 71 (hereinafter referred to as the high potential). Then, each time a discharge request is made, the surface electrode 72 is temporarily set to the same potential as the internal electrode 71 (hereinafter referred to as the low potential), and then set to the high potential again at a predetermined timing.

[0096] As a result, when the surface electrode 72 reaches a low potential, the piezoelectric ceramic layers 22A and 22B return to their original shape, and the volume of the pressurized chamber 62 increases compared to the initial state, i.e., the high potential state. At this time, negative pressure is applied inside the pressurized chamber 62, causing the liquid in the supply manifold 61 to be drawn into the pressurized chamber 62.

[0097] Subsequently, when the surface electrode 72 is again brought to a high potential, the piezoelectric ceramic layers 22A and 22B deform so as to become convex toward the pressurized chamber 62. That is, the volume of the pressurized chamber 62 decreases, causing the pressure inside the pressurized chamber 62 to become positive. As a result, the pressure of the liquid inside the pressurized chamber 62 increases, and droplets are discharged from the discharge holes 63.

[0098] In other words, the control unit 14 supplies a drive signal including a pulse referenced to a high potential to the surface electrode 72 using the driver IC 33 in order to eject droplets from the ejection port 63. The width of this pulse should be the Acoustic Length (AL), which is the time length over which the pressure wave propagates from the throttling 66 to the ejection port 63.

[0099] As a result, when the pressure inside the pressurizing chamber 62 reverses from a negative pressure state to a positive pressure state, the two pressures combine, allowing the droplets to be discharged at a stronger pressure.

[0100] Furthermore, in grayscale printing, grayscale expression is achieved by adjusting the droplet volume (volume) by the number of droplets continuously ejected from the ejection holes 63, i.e., the number of liquid ejections. For this reason, the number of liquid ejections corresponding to the specified grayscale expression are continuously performed from the ejection holes 63 corresponding to the specified dot area.

[0101] In this embodiment, the surface electrode 72 of the piezoelectric element 70 may have a base material BM containing a noble metal (see Figure 7) and a metal oxide MO (see Figure 7). Furthermore, in this embodiment, the metal oxide MO may be scattered within the base material BM.

[0102] As a result, the hardness of the surface electrode 72 increases, making it less likely for excessive strain to occur in the inactive portion adjacent to the active portion of the piezoelectric ceramic layer 22A when the piezoelectric element 70 is driven.

[0103] Therefore, in the inactive portion adjacent to the active portion of the piezoelectric ceramic layer 22A, the fixation of domains caused by excessive strain is reduced. Consequently, according to this embodiment, the coercive field of the piezoelectric element 70 increases, thereby reducing the driving degradation of the piezoelectric element 70.

[0104] Furthermore, in this embodiment, the area ratio of the metal oxide MO scattered within the base material BM may be 15% to 30%, and preferably 20% to 30%. In other words, in the SEM cross-sectional image of the surface electrode 72, the metal oxide MO that does not come into contact with the interface IF accounts for 15% to 30% of the area ratio of the base material BM, more preferably 20% to 30%.

[0105] As the area ratio of the metal oxide MO falls within the above range, the fixation of domains caused by excessive strain in the inactive portion adjacent to the active portion of the piezoelectric ceramic layer 22A is further reduced. Therefore, according to this embodiment, the coelectric field of the piezoelectric element 70 is further increased, and thus the driving degradation of the piezoelectric element 70 is further reduced.

[0106] Furthermore, in this embodiment, a metal oxide MO may be located at the interface IF (see Figure 7) between the base material BM and the piezoelectric ceramic layer 22A. This improves the adhesion between the surface electrode 72 and the piezoelectric ceramic layer 22A, thereby improving the reliability of the liquid discharge head 8.

[0107] Furthermore, in this embodiment, the area ratio of the metal oxide MO scattered within the base material BM to the metal oxide MO located at the interface IF between the base material BM and the piezoelectric ceramic layer 22A may be 20% to 60%, and preferably 40% to 60%. In other words, in the SEM cross-sectional image of the surface electrode 72, the metal oxide MO in contact with the interface IF accounts for 20% to 60% of the area ratio of the base material BM, more preferably 40% to 60%.

[0108] As the area ratio of the metal oxide MO falls within the above range, the fixation of domains caused by excessive strain in the inactive portion adjacent to the active portion of the piezoelectric ceramic layer 22A is further reduced. Therefore, according to this embodiment, the coelectric field of the piezoelectric element 70 is further increased, and thus the driving degradation of the piezoelectric element 70 is further reduced.

[0109] Furthermore, in this embodiment, the metal oxide MO may be exposed on the surface of the base material BM at the surface electrode 72 of the piezoelectric element 70.

[0110] As a result, the hardness of the surface electrode 72 increases, making it less likely for excessive strain to occur in the inactive portion adjacent to the active portion of the piezoelectric ceramic layer 22A when the piezoelectric element 70 is driven.

[0111] Therefore, in the inactive portion adjacent to the active portion of the piezoelectric ceramic layer 22A, the fixation of domains caused by excessive strain is reduced. Consequently, according to this embodiment, the coercive field of the piezoelectric element 70 increases, thereby reducing the driving degradation of the piezoelectric element 70.

[0112] Furthermore, in the embodiment, the area ratio of the metal oxide MO exposed on the surface of the base material BM may be 0.5% to 6%, and preferably 2% to 6%. In other words, in the SEM surface photograph of the surface electrode 72, the metal oxide MO exposed from the base material BM is 0.5% to 6%, more preferably 2% to 6%, in terms of area ratio relative to the base material BM.

[0113] As the area ratio of the metal oxide MO falls within the above range, the fixation of domains caused by excessive strain in the inactive portion adjacent to the active portion of the piezoelectric ceramic layer 22A is further reduced. Therefore, according to this embodiment, the coelectric field of the piezoelectric element 70 is further increased, and thus the driving degradation of the piezoelectric element 70 is further reduced.

[0114] In addition, in the embodiment, the metal oxide MO may include an oxide of the metal contained in the piezoelectric ceramic layer 22A. For example, if the piezoelectric ceramic layer 22A is composed of PZT, the metal oxide MO may include at least one of the oxides of lead (Pb), zirconium (Zr), and titanium (Ti) contained in PZT.

[0115] This improves the adhesion between the surface electrode 72 and the piezoelectric ceramic layer 22A, thereby improving the reliability of the liquid discharge head 8.

[0116] Furthermore, in this embodiment, the metal oxide MO may also contain Pb oxide. This reduces the excessive hardening of the surface electrode 72, which is composed of a precious metal base material BM, due to the addition of the metal oxide MO. Therefore, according to this embodiment, it is possible to reduce the inhibition of unimorph deformation of the piezoelectric element 70 due to excessive hardening of the surface electrode 72.

[0117] Furthermore, in this embodiment, the presence of Pb oxide in the metal oxide MO improves the adhesion between the surface electrode 72 and the piezoelectric ceramic layer 22A, thereby improving the reliability of the liquid discharge head 8.

[0118] Furthermore, in this embodiment, the base material BM may be composed mainly of a precious metal, such as Au or Ag. This reduces the likelihood of the surface electrode 72 becoming excessively hard, thereby reducing the inhibition of the unimorph deformation of the piezoelectric element 70 by the surface electrode 72.

[0119] Furthermore, in the embodiment, the piezoelectric element 70 may have a base material BM containing a noble metal and a metal oxide MO, and the electrode in which the metal oxide MO is scattered inside the base material BM may be the surface electrode 72. As a result, the coelectric field of the piezoelectric element 70 increases, thereby reducing the driving degradation of the piezoelectric element 70.

[0120] Furthermore, in the piezoelectric element 70, the electrode having a base material BM containing a noble metal and a metal oxide MO, with the metal oxide MO scattered within the base material BM, is not limited to a surface electrode 72, but may also be an internal electrode 71. This also increases the coelectric field of the piezoelectric element 70, thereby reducing the driving degradation of the piezoelectric element 70. [Examples]

[0121] The embodiments of this disclosure will be described in detail below. In the embodiments described below, PZT is used as the piezoelectric ceramic layer 22A, Au is used as the base material BM of the surface electrode 72, and Pb oxide is used as the metal oxide MO. However, this disclosure is not limited to the embodiments described below.

[0122] <Example 1> First, a laminate was prepared by stacking a flow channel member 21 (see Figure 6) and a piezoelectric actuator substrate 22 (see Figure 6). Next, a paste containing Au and Pb oxides was applied to the surface of the piezoelectric ceramic layer 22A on the piezoelectric actuator substrate 22 by screen printing. This paste was applied in a position and shape corresponding to the surface electrode 72 (see Figure 6).

[0123] Next, the laminate coated with a paste containing Au and Pb oxides was subjected to a baking treatment. This baking treatment was carried out in air at a maximum temperature (hereinafter also referred to as the baking temperature) of 660°C. As a result, the paste containing Au and Pb oxides was baked on, and surface electrodes 72 were formed on the surface of the piezoelectric ceramic layer 22A.

[0124] Next, a head body 20 (see Figure 6) was formed by attaching a connecting electrode 73 (see Figure 6) to the surface electrode 72, and the components shown in Figure 3 were attached to the formed head body 20 to obtain the liquid discharge head 8 (see Figure 3) of Example 1.

[0125] <Examples 2-5> Liquid discharge heads 8 of Examples 2 to 5 were obtained using the same method as in Example 1 described above. In Examples 2 to 5, the paste containing Au and Pb oxides was baked in air at baking temperatures of 675°C, 690°C, 705°C, and 720°C, respectively.

[0126] <Reference examples 1 and 2> Using the same method as in Example 1 described above, the liquid discharge heads 8 of Reference Examples 1 and 2 were obtained. In Reference Examples 1 and 2, the paste containing Au and Pb oxides was baked in air at baking temperatures of 750°C and 780°C, respectively.

[0127] <Various evaluations> Next, various evaluations were performed on the liquid discharge heads 8 of Examples 1-5 and Reference Examples 1 and 2 obtained above. First, the cross-sectional state of the surface electrodes 72 in Examples 1-5 and Reference Examples 1 and 2 was observed using an SEM (Scanning Electron Microscope). The observation results are shown in Figures 7-10.

[0128] Figures 7 to 10 show SEM images of the cross-sectional state of the surface electrode 72 in Example 1, Example 3, Example 5, and Reference Example 2.

[0129] As shown in Figures 7 to 9, in the surface electrodes 72 of Examples 1, 3, and 5, metal oxide MO composed of Pb oxide was scattered within the base material BM composed of Au. Although not shown in the figures, similarly, in the surface electrodes 72 of Examples 2 and 4, metal oxide MO composed of Pb oxide was scattered within the base material BM composed of Au.

[0130] On the other hand, as shown in Figure 10, in the surface electrode 72 of Reference Example 2, the metal oxide MO composed of Pb oxide was not scattered within the base material BM composed of Au, but was located locally. Although not shown in the figure, similarly in the surface electrode 72 of Reference Example 1, the metal oxide MO composed of Pb oxide was not scattered within the base material BM composed of Au, but was located locally.

[0131] Furthermore, as shown in Figures 7 to 10, in the surface electrodes 72 of Examples 1 to 5 and Reference Examples 1 and 2, metal oxide MO was also located at the interface IF between the base material BM and the piezoelectric ceramic layer 22A. Note that the black dot-like areas in Figures 7 to 10 are not metal oxide MO but voids.

[0132] Next, from the SEM images of the cross-sectional state of the surface electrode 72 in each of the embodiments and reference examples described so far, the area ratio of metal oxide MO within the electrode per unit area and the area ratio of metal oxide MO at the interface IF per unit area were determined, respectively.

[0133] Figure 11 shows the relationship between the baking temperature of the surface electrode 72 and the area ratio of metal oxide MO within the electrode and at the interface IF of the surface electrode 72. In each example (baking temperature of 720°C or less), since metal oxide MO is scattered within the base material BM, the area ratio of metal oxide MO within the electrode was higher compared to each reference example (baking temperature of 750°C or more), as shown in Figure 11.

[0134] In each example, the area ratio of metal oxide MO within the electrode was in the range of 15% to 30%. Furthermore, in Examples 1 to 4 (baking temperature 660°C to 705°C), the area ratio of metal oxide MO within the electrode was in the range of 20% to 30%.

[0135] Furthermore, as shown in Figure 11, the area ratio of metal oxide MO at the interface IF did not change significantly in Examples 1-5 and Reference Examples 1 and 2.

[0136] Figure 12 shows the relationship between the baking temperature of the surface electrode 72 and the area ratio of metal oxide MO within the electrode to the metal oxide MO at the interface IF of the surface electrode 72. In each example (baking temperature of 720°C or less), since the metal oxide MO is scattered within the base material BM, the ratio of metal oxide MO within the electrode to the interface IF was higher compared to Reference Examples 1 and 2 (baking temperature of 750°C or more), as shown in Figure 12.

[0137] In each example, the area ratio of metal oxide MO in the electrode to the interface IF was in the range of 20% to 60%. Furthermore, in Examples 1 to 4 (baking temperature 660°C to 705°C), the area ratio of metal oxide MO in the electrode to the interface IF was in the range of 40% to 60%.

[0138] Next, the surface condition of the surface electrodes 72 in Examples 1-5 and Reference Examples 1 and 2 was observed using a scanning electron microscope (SEM). The observation results are shown in Figures 13-16. Figures 13-16 show SEM images of the surface condition of the surface electrodes 72 in Examples 1, 3, 5, and 2.

[0139] As shown in Figures 13 to 15, in the surface electrodes 72 of Examples 1, 3, and 5, granular metal oxide MO composed of Pb oxide was exposed on the surface of the base material BM composed of Au. Although not shown in the figures, similarly, in the surface electrodes 72 of Examples 2 and 4, granular metal oxide MO composed of Pb oxide was exposed on the surface of the base material BM composed of Au.

[0140] On the other hand, as shown in Figure 16, in Reference Example 2, the surface electrode 72 did not have metal oxide MO, composed of Pb oxide, exposed on the surface of the base material BM, which is composed of Au. Although not shown in the figure, similarly, in Reference Example 1, the surface electrode 72 also did not have metal oxide MO, composed of Pb oxide, exposed on the surface of the base material BM, which is composed of Au.

[0141] Next, the area ratio of metal oxide MO on the electrode surface per unit area was determined from the SEM images of the surface state of the surface electrode 72 in each of the embodiments and reference examples described so far. Figure 17 shows the relationship between the baking temperature of the surface electrode 72 and the area ratio of metal oxide MO on the surface of the surface electrode 72.

[0142] As shown in Figure 17, in each example, the surface area ratio of metal oxide MO was in the range of 0.5% to 6%. In Examples 2 to 4 (baking temperature 675°C to 705°C), the surface area ratio of metal oxide MO was in the range of 2% to 6%. On the other hand, in Reference Examples 1 and 2 (baking temperature 750°C or higher), the surface area ratio of metal oxide MO was zero because the metal oxide MO was not exposed on the surface of the base material BM.

[0143] Next, the coelectric field of the piezoelectric element 70 in each embodiment and reference example was evaluated. Specifically, using a device with a flying probe method, a voltage in the range of -100V to 100V was applied, and the hysteresis curve of the piezoelectric element 70 was measured. Then, the coelectric field of the piezoelectric element 70 was calculated from the value at the point where the hysteresis curve intersects the x-axis (i.e., y=0) in the measured hysteresis curve.

[0144] Figure 18 shows the relationship between the baking temperature of the surface electrode 72 and the coelectric field of the piezoelectric element 70. As shown in Figure 18, in each embodiment (baking temperature of 720°C or less), the coelectric field value of the piezoelectric element 70 was higher compared to each reference example (baking temperature of 750°C or more).

[0145] Furthermore, from the observation results of the cross-sectional SEM images (see Figures 7 to 10) and the results in Figure 18, it can be seen that in this embodiment, the presence of scattered metal oxide MO particles within the base material BM results in a high coercive field value in the piezoelectric element 70.

[0146] This is presumably because the presence of metal oxide MO scattered within the base material BM increases the hardness of the surface electrode 72, making it less likely for excessive strain to occur in the inactive region adjacent to the active region of the piezoelectric ceramic layer 22A when the piezoelectric element 70 is driven, thus reducing domain fixation in that inactive region.

[0147] Furthermore, the results in Figure 11 and Figure 18 show that, in this embodiment, the coercive field value in the piezoelectric element 70 is increased by setting the area ratio of the metal oxide MO in the electrode to a range of 15% to 30%.

[0148] Furthermore, the results in Figure 11 and Figure 18 show that, in this embodiment, by setting the area ratio of metal oxide MO in the electrode to a range of 20% to 30%, the coercive field value in the piezoelectric element 70 is further increased.

[0149] Furthermore, the results in Figure 12 and Figure 18 show that, in this embodiment, the coercive field value in the piezoelectric element 70 is increased by setting the area ratio of the metal oxide MO in the electrode to the metal oxide MO at the interface IF to a range of 20% to 60%.

[0150] Furthermore, the results in Figure 12 and Figure 18 show that, in this embodiment, by setting the area ratio of metal oxide MO in the electrode to the metal oxide MO at the interface IF to a range of 40% to 60%, the coercive field value in the piezoelectric element 70 is further increased.

[0151] Furthermore, the results in Figures 17 and 18 show that, in this embodiment, the coercive field value of the piezoelectric element 70 is increased by setting the area ratio of the metal oxide MO on the surface to a range of 0.5% to 6%.

[0152] Furthermore, the results in Figures 17 and 18 show that, in this embodiment, the coercive field value in the piezoelectric element 70 is further increased by setting the surface area ratio of the metal oxide MO to the range of 2% to 6%.

[0153] Next, the progression of drive degradation was evaluated for the piezoelectric element 70 in Example 3 and Reference Example 1. Specifically, for the liquid discharge head 8 in Example 3 and Reference Example 1, the initial discharge amount was measured, then a pulse waveform of a predetermined frequency was applied to the piezoelectric element 70 to induce drive degradation, and the discharge amount was measured again after a predetermined cycle of operation.

[0154] Figure 19 shows the progression of drive degradation between the piezoelectric element 70 of Example 3 and the piezoelectric element 70 of Reference Example 1. By comparing the piezoelectric element 70 of Example 3 and the piezoelectric element 70 of Reference Example 1, it can be seen that the drive degradation of the piezoelectric element 70 is reduced as the value of the coercive field in the piezoelectric element 70 increases.

[0155] While embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above, and various modifications are possible without departing from its spirit.

[0156] Further effects and other embodiments can be readily derived by those skilled in the art. Therefore, broader embodiments of this disclosure are not limited to the specific details and representative embodiments expressed and described above. Accordingly, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents.

[0157] Furthermore, this technology can also be configured as follows. (1) It has a piezoelectric element that deforms when a voltage is applied, The piezoelectric element is Piezoelectric ceramic material and An electrode for applying voltage to the piezoelectric ceramic body, It has, The electrode comprises a base material containing a noble metal and a metal oxide, wherein the metal oxide is scattered within the base material. Piezoelectric actuator. (2) The area ratio of the metal oxides scattered within the base material is 15% to 30%. The piezoelectric actuator described in (1) above. (3) The area ratio of the metal oxides scattered within the base material is 20% to 30%. The piezoelectric actuator described in (1) above. (4) The metal oxide is located at the interface between the base material and the piezoelectric ceramic body. A piezoelectric actuator as described in any one of (1) to (3) above. (5) The area ratio of the metal oxides scattered within the base material to the metal oxides located at the interface between the base material and the piezoelectric ceramic body is 20% to 60%. The piezoelectric actuator described in (4) above. (6) The area ratio of the metal oxides scattered within the base material to the metal oxides located at the interface between the base material and the piezoelectric ceramic body is 40% to 60%. The piezoelectric actuator described in (4) above. (7) It has a piezoelectric element that deforms when a voltage is applied, The piezoelectric element is Piezoelectric ceramic material and An electrode for applying voltage to the piezoelectric ceramic body, It has, The electrode comprises a base material containing a noble metal and a metal oxide, wherein the metal oxide is exposed on the surface of the base material. Piezoelectric actuator. (8) The area ratio of the metal oxide exposed on the surface of the base material is 0.5% to 6%. The piezoelectric actuator described in (7) above. (9) The area ratio of the metal oxide exposed on the surface of the base material is 2% to 6%. The piezoelectric actuator described in (7) above. (10) The metal oxide includes the oxide of the metal contained in the piezoelectric ceramic body. A piezoelectric actuator as described in any one of (1) to (9) above. (11) The aforementioned metal oxide includes Pb oxide. A piezoelectric actuator as described in any one of (1) to (9) above. (12) The electrode is a surface electrode located on the surface of the piezoelectric ceramic body. A piezoelectric actuator as described in any one of (1) to (11) above. (13) A nozzle that dispenses liquid droplets, A pressurizing chamber connected to the nozzle, A piezoelectric element that deforms upon application of voltage to deform the pressurized chamber, and It has, The piezoelectric element is Piezoelectric ceramic material and An electrode for applying voltage to the piezoelectric ceramic body, It has, The electrode comprises a base material containing a noble metal and a metal oxide, wherein the metal oxide is scattered within the base material. Liquid dispensing head. (14) A recording device having the liquid discharge head described in (13) above. [Explanation of Symbols]

[0158] 1. Printer (an example of a recording device) 8 liquid dispensing heads 22A Piezoelectric ceramic layer (an example of a piezoelectric ceramic body) 62 Pressurized chamber 63 Discharge port (an example of a nozzle) 70 Piezoelectric element 72. Surface electrodes (an example of an electrode) BM base material MO metal oxides IF interface

Claims

1. It has a piezoelectric element that deforms when a voltage is applied, The piezoelectric element is Piezoelectric ceramic material and An electrode for applying voltage to the piezoelectric ceramic body, It has, The electrode comprises a base material containing a noble metal and a metal oxide, wherein the metal oxide is scattered within the base material. The metal oxide is located at the interface between the base material and the piezoelectric ceramic body. The area ratio of the metal oxides scattered within the base material to the metal oxides located at the interface between the base material and the piezoelectric ceramic body is 20% to 60%. Piezoelectric actuator.

2. The area ratio of the metal oxides scattered within the base material is 15% to 30%. The piezoelectric actuator according to claim 1.

3. The area ratio of the metal oxides scattered within the base material is 20% to 30%. The piezoelectric actuator according to claim 1.

4. The area ratio of the metal oxides scattered within the base material to the metal oxides located at the interface between the base material and the piezoelectric ceramic body is 40% to 60%. The piezoelectric actuator according to claim 1.

5. The metal oxide includes the oxide of the metal contained in the piezoelectric ceramic body. A piezoelectric actuator according to any one of claims 1 to 4.

6. The aforementioned metal oxide includes Pb oxide. A piezoelectric actuator according to any one of claims 1 to 4.

7. The electrode is a surface electrode located on the surface of the piezoelectric ceramic body. A piezoelectric actuator according to any one of claims 1 to 4.

8. A nozzle that dispenses liquid droplets, A pressurizing chamber connected to the nozzle, A piezoelectric element that deforms upon application of voltage to deform the pressurized chamber, and It has, The piezoelectric element is Piezoelectric ceramic material and An electrode for applying voltage to the piezoelectric ceramic body, It has, The electrode comprises a base material containing a noble metal and a metal oxide, wherein the metal oxide is scattered within the base material. The metal oxide is located at the interface between the base material and the piezoelectric ceramic body. The area ratio of the metal oxides scattered within the base material to the metal oxides located at the interface between the base material and the piezoelectric ceramic body is 20% to 60%. Liquid dispensing head.

9. A recording device having a liquid dispensing head as described in claim 8.

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