Liquid discharge device, recording device, and piezoelectric actuator

Abstract

Provided is a piezoelectric actuator including a plurality of individual actuators that pressurize a plurality of pressure chambers, respectively. Each of the plurality of individual actuators includes a central piezoelectric unit overlapping the center of the corresponding pressure chamber, and a peripheral piezoelectric unit overlapping the inner peripheral part of the corresponding pressure chamber. The central piezoelectric unit is constituted of at least one first piezoelectric layer and at least two first electrodes alternately layered on the side facing the pressurizing surface. The peripheral edge piezoelectric part is constituted of at least two second piezoelectric layers and at least three second electrodes alternately layered on the side facing the pressurizing surface. The first electrode of the lowermost layer and the second electrode of the uppermost layer are positioned in the same layer and connected to each other to constitute a common electrode. The common electrodes of the plurality of individual actuators are electrically connected to each other. The number of the second piezoelectric layers is an even number, and the second electrode of the lowermost layer is electrically connected to the common electrode.

Description

Liquid ejection device, recording device, and piezoelectric actuator

[0001] The present disclosure relates to a liquid ejection device, a recording device having the liquid ejection device, and a piezoelectric actuator that can be used in the liquid ejection device.

[0002] A liquid ejection device (for example, an inkjet head) that ejects droplets (for example, ink droplets) toward a recording medium (for example, paper) is known (for example, Patent Document 1 below). Such a liquid ejection device has, for example, a nozzle, a pressure chamber communicating with the nozzle, and a piezoelectric actuator that pressurizes the pressure chamber. When the pressure chamber filled with ink is pressurized, droplets are ejected from the nozzle. The piezoelectric actuator has, for example, an active region that overlaps the pressure chamber and is driven to flexibly deform. Due to the flexible deformation of the active region, the volume of the pressure chamber changes, and as a result, pressure fluctuations for ejecting ink occur.

[0003] In Patent Document 1, in a top view of the pressure chamber, the piezoelectric actuator has a first active region that overlaps the central portion of the pressure chamber and a second active region that overlaps the inner side and the peripheral portion of the pressure chamber. The second active region is located closer to the pressure chamber than the first active region. The first active region and the second active region cause flexible deformation in opposite directions. As a result, the amount of change in the volume of the pressure chamber is increased compared to a mode in which only the flexible deformation of the first active region is used.

[0004] International Publication No. 2021 / 200633

[0005] A liquid dispensing device according to one aspect of the present disclosure includes a flow channel member and a piezoelectric actuator. The flow channel member has a pressurizing surface and a plurality of pressure chambers arranged along the pressurizing surface. The piezoelectric actuator overlaps the pressurizing surface. The piezoelectric actuator has a plurality of individual actuators that pressurize each of the plurality of pressure chambers. Each of the plurality of individual actuators has a central piezoelectric section and a peripheral piezoelectric section. The central piezoelectric section is composed of one or more first piezoelectric layers and two or more first electrodes that are alternately overlapped on the side facing the pressurizing surface. The two or more first electrodes overlap the center of the corresponding pressure chamber. The peripheral piezoelectric section is composed of two or more second piezoelectric layers and three or more second electrodes that are alternately overlapped on the side facing the pressurizing surface. The three or more second electrodes overlap the inner peripheral edge of the corresponding pressure chamber. In the piezoelectric actuator, the side facing the pressurizing surface is referred to as the lower layer side, and the side opposite to the pressurizing surface is referred to as the upper layer side. In this configuration, the first electrode at the bottom and the second electrode at the top are located in the same layer and are connected to each other, forming a shared electrode. The shared electrodes of the multiple individual actuators are electrically connected to each other. The number of the two or more second piezoelectric layers is even. The second electrode at the bottom is electrically connected to the shared electrode.

[0006] A recording device according to one aspect of the present disclosure includes a liquid dispensing device and a transport device for moving the liquid dispensing device and a recording medium relative to each other.

[0007] A piezoelectric actuator according to one aspect of the present disclosure has a plurality of individual actuators that deform when a voltage is applied. Each of the plurality of individual actuators has a central piezoelectric section and a peripheral piezoelectric section. The central piezoelectric section is composed of one or more first piezoelectric layers and two or more first electrodes that are alternately overlapping toward the first side. The peripheral piezoelectric section is composed of two or more second piezoelectric layers and three or more second electrodes that are alternately overlapping toward the first side, and is located around the central piezoelectric section when viewed from above. In the piezoelectric actuator, the first side is referred to as the lower layer side, and the side opposite to the first side is referred to as the upper layer side. In this case, the lowest first electrode and the uppermost second electrode are located in the same layer and are connected to each other to form a shared electrode. The shared electrodes of the plurality of individual actuators are electrically connected to each other. The number of the two or more second piezoelectric layers is even. The lowest second electrode is electrically connected to the shared electrode.

[0008] A schematic side view of the recording device according to the embodiment. A schematic plan view of the recording device of Figure 1. A schematic perspective view showing the ejection surface of the head in the recording device of Figure 1. A schematic cross-sectional view along line IV-IV in Figure 3. A schematic cross-sectional view illustrating the operating principle of the piezoelectric actuator according to the embodiment. A schematic exploded perspective view of the piezoelectric actuator according to the first example. A schematic cross-sectional view of an individual actuator in the piezoelectric actuator of Figure 6. A schematic exploded perspective view of an individual actuator in Figure 7. A schematic cross-sectional view of an individual actuator according to the second example. A schematic exploded perspective view of an individual actuator in Figure 9. A schematic cross-sectional view of an individual actuator according to the third example. A schematic cross-sectional view of an individual actuator according to the fourth example. A schematic cross-sectional view of an individual actuator according to the fifth example. A schematic cross-sectional view of an individual actuator according to the sixth example. A schematic cross-sectional view of an individual actuator according to the seventh example. A schematic exploded perspective view of a piezoelectric actuator according to the eighth example.

[0009] The diagrams used in the following explanation are schematic. Therefore, for example, the dimensional ratios on the drawings do not necessarily match those of reality. Furthermore, dimensional ratios may not match between drawings. Certain shapes and / or dimensions may be exaggerated, or details may be omitted. However, the above does not negate the possibility that the actual shape and / or dimensions may be as shown in the drawings, or that the characteristics of the shape and / or dimensions may be extracted from the drawings. Note that the term "shape" may or may not include dimensions. Either interpretation is acceptable as long as it does not create a contradiction.

[0010] For convenience, the drawings may be labeled with a Cartesian coordinate system D1D2D3 (or D4D5D3), and terms such as D1 direction, D2 direction, and D3 direction may be used. The liquid discharge head according to the embodiment may be used in any orientation. However, for convenience, terms (top surface, bottom surface, etc.) that assume the +D3 side is upward may be used.

[0011] Regarding descriptions of aspects explained relatively later, only the differences from those explained earlier should be noted. Unless otherwise specified, matters may be treated the same as those explained earlier, or inferred from those explained earlier. Furthermore, for the sake of convenience, corresponding configurations across multiple aspects may be assigned the same reference numerals, even if there are differences. Multiple aspects may be combined as appropriate.

[0012] (Outline of Embodiments) Figure 1 is a schematic side view showing a printer 1 (an example of a recording device) according to an embodiment. Figure 2 is a schematic top view of the printer 1. In the printer 1, for example, a medium P (an example of a recording medium), such as paper, is transported generally from the -D2 side to the +D2 side (or to the opposite side). One or more (multiple in the illustrated example) heads 3 (each an example of a liquid ejection device) are located above the medium P. An image (which may include characters) is formed on the medium P by ejecting ink (an example of a liquid) from the heads 3 toward the medium P.

[0013] Figure 3 is a schematic perspective view of the head body 5, which constitutes at least the lower part of the head 3, as seen from its lower surface (discharge surface 7a). The head body 5 has a flow path member 7 that constitutes the discharge surface 7a. Multiple nozzles 9 open on the discharge surface 7a, which discharge ink droplets (an example of liquid droplets) toward the media P.

[0014] Figure 4 is a cross-sectional view taken along line IV-IV in Figure 3. However, only the ejection surface 7a and its vicinity are shown, and the upper part of the head body 5 is not shown. In addition to the flow path member 7 described above, the head body 5 has a piezoelectric actuator 11 that overlaps the upper surface (pressure surface 7b) of the flow path member 7. The flow path member 7 has a flow path 13 that includes a nozzle 9. The flow path 13 is filled with ink. Pressure is applied to the ink in the flow path 13 by the piezoelectric actuator 11, causing ink droplets to be ejected from the nozzle 9.

[0015] More specifically, the flow path 13 includes multiple pressure chambers 15 (only one is shown in Figure 4) leading to each of the multiple nozzles 9. The pressure chambers 15 open to, for example, the pressurized surface 7b. The piezoelectric actuator 11, on the other hand, has multiple individual actuators 17 that overlap each of the multiple pressure chambers 15. The individual actuators 17 deform downward and / or upward. This changes the volume of the pressure chambers 15, and consequently, the pressure of the ink in the pressure chambers 15 fluctuates. This pressure fluctuation is used to eject the ink from the nozzles 9.

[0016] Figure 5 is a schematic cross-sectional view illustrating the principle of deflection deformation of the individual actuator 17, and corresponds to the upper part of Figure 4. For illustrative purposes, the hatching indicating that it is a cross-section has been omitted (the same applies to other cross-sectional views described later). This figure shows the state in which the individual actuator 17 has undergone deflection deformation.

[0017] Each individual actuator 17 (piezoelectric actuator 11) has a first constituent layer 19A and a second constituent layer 19B that are stacked from top to bottom. The first constituent layer 19A has a central piezoelectric part 19AC that overlaps the center of the pressure chamber 15 and a peripheral non-driven part 19AP outside of it. The second constituent layer 19B has a peripheral piezoelectric part 19BP that overlaps the inner peripheral edge of the pressure chamber 15 and a central non-driven part 19BC inside of it.

[0018] When causing deflection deformation in the individual actuator 17, for example, the central piezoelectric part 19AC is contracted in a direction along its surface by the piezoelectric lateral effect. This contraction is restricted by the central non-driven part 19BC. Therefore, both bend in a way that is convex downwards, like a bimetallic strip. Simultaneously with the above, the peripheral piezoelectric part 19BP is contracted in a direction along its surface by the piezoelectric lateral effect. This contraction is restricted by the peripheral non-driven part 19AP. Therefore, both bend in a way that is concave downwards, like a bimetallic strip. As a result, the central side of the individual actuator 17 is displaced downwards due to the downward convex deflection on the central side and the downward concave deflection on the peripheral side.

[0019] Although the example given was the case where the central piezoelectric section 19AC and the peripheral piezoelectric section 19BP are retracted, when both are extended, the individual actuator 17 is displaced upward on the central side, contrary to the above. In the description of the embodiment, for convenience, it may be assumed that the central piezoelectric section 19AC and the peripheral piezoelectric section 19BP are retracted unless otherwise specified.

[0020] Figure 7 is a cross-sectional view showing an individual actuator 17A as a specific example (first example) of the individual actuator 17, and corresponds to Figure 5. In this figure, hatching is applied to the piezoelectric elements of the central piezoelectric part 19AC and the peripheral piezoelectric part 19BP. Figure 8 is an exploded perspective view of the individual actuator 17A. However, the illustration of the piezoelectric layer and the thickness of the conductor, which will be described later, is omitted. Also, hatching is applied to the upper surface of the conductor (i.e., the surface that is not a cross-section) for convenience.

[0021] The central piezoelectric section 19AC is composed of one or more (two in the illustrated example) piezoelectric layers (21A and 21B, each an example of a first piezoelectric layer) and two or more (three in the illustrated example) electrodes (23A to 23C, each an example of a first electrode) that overlap alternately in the D3 direction. The electrodes 23A to 23C overlap in the center of the pressure chamber 15. At least one of two electrodes adjacent to each other in the D3 direction does not overlap the inner peripheral edge of the pressure chamber 15. By applying a voltage (electric field) to the piezoelectric layers 21A and 21B with the electrodes 23A to 23C, a piezoelectric transverse effect occurs, and consequently, the central piezoelectric section 19AC contracts in a direction along its plane.

[0022] The peripheral piezoelectric portion 19BP is composed of two or more (two in the illustrated example) piezoelectric layers (21C and 21D, each an example of a second piezoelectric layer) that overlap alternately in the D3 direction and three or more (three in the illustrated example) electrodes (23D to 23F, each an example of a second electrode). The electrodes 23D to 23F overlap the inner peripheral edge of the pressure chamber 15. At least one of two adjacent electrodes in the D3 direction does not overlap the center of the pressure chamber 15. By applying a voltage (electric field) to the piezoelectric layers 21C and 21D by the electrodes 23D to 23F, a piezoelectric transverse effect occurs, and consequently, the peripheral piezoelectric portion 19BP contracts in a direction along its surface.

[0023] In the following, the piezoelectric layers 21A to 21D (and other piezoelectric layers described later) may be referred to collectively as piezoelectric layer 21 without distinction. The electrodes 23A to 23F (and other electrodes described later) may be referred to collectively as electrode 23 without distinction.

[0024] The number of piezoelectric layers 21 in the peripheral piezoelectric section 19BP is even. As shown by the dashed line in Figure 8, the uppermost electrode 23D and the lowermost electrode 23F are electrically connected in the peripheral piezoelectric section 19BP. Therefore, for example, by setting every other electrode 23, including the uppermost electrode 23D and the lowermost electrode 23F, to a constant potential and changing the potential of the electrodes 23 in between (by inputting a drive signal), an electric field can be applied to the piezoelectric layers 21 (21C and 21D) in the peripheral piezoelectric section 19BP.

[0025] The lowest electrode 23C in the central piezoelectric section 19AC and the uppermost electrode 23D in the peripheral piezoelectric section 19BP are located in the same layer and are connected to each other to form a shared electrode 23Z. In Figure 5, for convenience, the first constituent layer 19A and the second constituent layer 19B are depicted as if they overlap each other (as if a single conductive layer is not shared).

[0026] Figure 6 is an exploded perspective view of a part of a piezoelectric actuator 11A, which is a specific example (first example) of the piezoelectric actuator 11, and corresponds to a diagram showing the configuration shown in Figure 8 for multiple individual actuators 17A. As can be seen from Figures 6 and 8, the shared electrodes 23Z of the multiple individual actuators 17A are electrically connected to each other to form a common electrode 23Y.

[0027] Since the multiple shared electrodes 23Z are connected to each other, a constant potential (e.g., ground potential) is usually applied when driving the multiple individual actuators 17A individually. The same applies to the electrodes electrically connected to the common electrode 23Y (e.g., the lowest electrode 23F of the peripheral piezoelectric part 19BP).

[0028] With the above configuration, for example, since the peripheral piezoelectric portion 19BP is composed of multiple piezoelectric layers 21C and 21D, the piezoelectric layer 21 can be made thinner compared to the case where the peripheral piezoelectric portion 19BP of the same thickness is composed of a single piezoelectric layer 21. As a result, for example, it becomes easier to increase the intensity of the electric field applied to the piezoelectric layer 21 and thereby increase the amount of deformation of the peripheral piezoelectric portion 19BP. Because it is easier to increase the amount of deformation, it also becomes easier to use a material with a low piezoelectric constant (for example, a lead-free piezoelectric material) as the material for the piezoelectric layer 21.

[0029] Furthermore, since the lowest electrode 23C of the central piezoelectric section 19AC and the uppermost electrode 23D of the peripheral piezoelectric section 19BP are located on the same layer and connected to each other to form a shared electrode 23Z, the configuration is simplified and miniaturized. Moreover, by connecting multiple shared electrodes 23Z to each other to form a common electrode 23Y, the effects of simplification and miniaturization are easily enhanced.

[0030] Since the piezoelectric layer 21 of the peripheral piezoelectric part 19BP has an even number of layers, and the bottom electrode 23F of the peripheral piezoelectric part 19BP is connected to the common electrode 23Y, there is a high probability that a constant potential (e.g., ground potential) is applied to the electrode 23F closest to the pressure chamber 15. As a result, the probability of an electric field being generated in the flow path 13 is reduced.

[0031] By reducing the probability of an electric field being generated in the channel 13, the probability of unintended ink flow is reduced, for example. Factors that cause such flow include, for example, Coulomb force acting on charged ink, changes in wettability (electrowetting), electrophoresis, and dielectrophoresis.

[0032] As described above, according to the embodiment, an increase in the deformation amount of the piezoelectric actuator 11 can be achieved with a simple and compact configuration, while reducing the influence of the electrode 23 on the ink (an example of a liquid), thereby reducing the likelihood of a decrease in ink ejection characteristics.

[0033] It should be noted that the effects described above do not necessarily have to be achieved. Furthermore, technical ideas from perspectives different from those described above may be extracted from this disclosure. In this case, for example, the peripheral piezoelectric portion 19BP may not be provided, the peripheral piezoelectric portion 19BP may not have an even number of piezoelectric layers 21, the multi-purpose electrode 23Z may not be configured, and the bottom electrode 23F may not be connected to the common electrode 23Y.

[0034] The above is an overview of the embodiments. Below, the embodiments will be described in general order. 1. Printer (Figures 1 and 2) 2. Head (Figures 3 and 4) 2.1. Head in general 2.2. Flow channel members 3. Piezoelectric actuator 3.1. First example (Figures 6 to 8) 3.1.1. Piezoelectric actuator in general 3.1.2. Active regions of the central piezoelectric section and peripheral piezoelectric section 3.1.2.1. Overview of the active region 3.1.2.2. Planar shape of the active region 3.1.3. Piezoelectric layer 3.1.4. Conductor 3.1.5. Electrode 3.1.6. Connection between electrodes 3.1.7. Operation 3.2. Second example (Figures 9 and 10) 3.3. Third example (Figure 11) 3.4. Fourth example (Figure 12) 3.5. Fifth example (Figure 13) 3.6. Sixth example (Figure 14) 3.7. Seventh example (Figure 15) 3.8. Eighth example (Figure 16) 4. Method for manufacturing a piezoelectric actuator 5. Summary of embodiments

[0035] (1. Printer) The configuration of the printer 1 shown in Figures 1 and 2 may be various configurations, except for the configuration related to the piezoelectric actuator 11, and may be a known configuration, for example. The configurations shown in Figures 1 and 2 are merely examples. In the following, the printer 1 will be briefly described in general, using the configurations shown in Figures 1 and 2 as an example.

[0036] As previously described, printer 1 has multiple heads 3 (an example of a liquid ejection head). In addition, printer 1 may also have, for example, a transport device 25 for transporting media P and a controller 27 for controlling various parts of printer 1.

[0037] Printer 1 is configured as a so-called line printer. That is, the head unit 29, which includes at least one head 3 (five in the example in Figure 2), extends over approximately the entire width (D1 direction) of the media P. When the media P is transported, printing is performed on a strip-shaped area extending in the D1 direction, thereby forming a two-dimensional image.

[0038] In each head unit 29, the five heads 3 are arranged in a staggered pattern so that there is no gap in the D1 direction when viewed in the D2 direction. Depending on the configuration of the head 3 and the like, the plurality of heads 3 may be arranged linearly in the D1 direction. In each head unit 29, the configuration for fixing the plurality of heads 3 to each other is arbitrary. In FIGS. 1 and 2, a frame 31 having an opening (not shown) for exposing the head 3 downward is illustrated.

[0039] Note that the printer 1 is not limited to a line printer. For example, the printer 1 may be a serial printer. In a serial printer, for example, an operation of printing while moving a head (head unit) in a direction (D1 direction) intersecting the conveyance direction of the medium P and the conveyance of the medium P are alternately performed.

[0040] The printer 1 has a total of four head units 29. The four head units 29 are arranged, for example, in the conveyance direction of the medium P. The five heads 3 in each head unit 29 correspond to the same color ink. The four head units 29 correspond to inks of different colors (four-color inks). The four-color inks are, for example, magenta (M), yellow (Y), cyan (C), and black (K). Thereby, the printer 1 functions as a color printer.

[0041] Unlike the above description, the printer 1 may perform single-color printing, or conversely, may perform printing with more than four colors. That is, the number of colors is arbitrary. Also, two or more head units 29 may correspond to one color. Conversely, one head unit 29 may correspond to two or more colors, such as when one head 3 corresponds to two or more colors. The number of heads 3 included in one head unit 29 is arbitrary and may be one. As understood from the above, the number of heads 3 that the printer 1 has is arbitrary.

[0042] Printer 1 performs printing on, for example, a roll paper as the medium P. However, the medium P may be a sheet of paper. Also, the size of the medium P is arbitrary. For example, the size of the medium P may be as small as a receipt, or may be the size of printing paper commonly used in offices, or may be as large as a poster.

[0043] The configuration of the conveyance device 25 is arbitrary. In FIGS. 1 and 2, a configuration in which the medium P is conveyed by rotating a roller sandwiching the medium P is illustrated. As other configurations, for example, a configuration in which the medium P is conveyed by conveying a belt adsorbing the medium P, and a configuration in which the medium P is conveyed by rotating a drum around which the medium P is wound can be mentioned. The conveyance device 25 relatively moves the head 3 and the medium P in a higher-level concept.

[0044] The controller 27 is configured to include, for example, a computer, and controls the head 3 and the conveyance device 25 based on print data including image data.

[0045] In addition to the above components, the printer 1 may have various other components. Although not particularly illustrated, examples are given below. ・ Drying device: For example, it promotes the drying of ink. ・ Coating device: For example, it uniformly applies a transparent coating agent to the medium P. ・ Cleaning device: For example, it cleans the head 3. Note that the printer 1 may use the head 3 for applying a coating agent in addition to or instead of printing with ink having a color.

[0046] (2. Head) (2.1. Head in general) Head 3 has a head body 5 as shown in Figure 3, as previously described. Although not specifically shown, head 3 may also have the following components: ・Circuit board: For example, connected to head body 5 (more specifically, a flexible circuit board not shown, as described later). ・Connector: Mounted on the above circuit board and contributes to the electrical connection between head body 5 and controller 27. ・Housing: For example, covers the top of head body 5 and houses the above circuit board. Regardless of whether head 3 has components other than head body 5, head body 5 may be considered an example of the liquid dispensing head of this disclosure.

[0047] As previously described, the head body 5 has a flow channel member 7 and a piezoelectric actuator 11. The head 3 may also have, for example, the following components: ・Rear member 33: Overlaps onto the upper surface of the flow channel member 7. In the example in Figure 3, it has a portion that overlaps with the flow channel member 7 and a flange-shaped portion. ・Flexible substrate (not shown): Connected to the piezoelectric actuator 11. ・Driver 49 (Schematically shown in Figure 8): Mounted on the flexible substrate and inputs a drive signal to the piezoelectric actuator 11 based on a signal from the controller 27. The specific division of roles between the driver 49 and the controller 27 is arbitrary. The combination of the flow channel member 7 and the piezoelectric actuator 11 is sometimes referred to as the front member (reference numeral omitted). Contrary to the above description, the front member may be considered as the head body or as an example of the liquid dispensing device of this disclosure.

[0048] The piezoelectric actuator 11 (not shown in Figure 3 as it is hidden by the flow path member 7) is, for example, slightly smaller than the flow path member 7 in a plan view. The rear member 33, although not specifically shown, has a recess on its lower surface for housing the piezoelectric actuator 11 and overlaps the upper surface of the flow path member 7 around the piezoelectric actuator 11. The rear member 33 contributes, for example, to mediating between the front member and other components. For example, the rear member 33 contributes to the positioning of the front member relative to the frame. Also, for example, the rear member 33 mediates between a tank (not shown) and the flow path member 7 with respect to the flow of liquid.

[0049] (2.2. Flow channel member) As shown in Figure 3, the general shape of the flow channel member 7 is, for example, a rectangular flat plate. When referring to a rectangle, the corners may be chamfered and relatively small irregularities may be formed on the edges, as long as no inconsistencies arise. The same applies to other members and other shapes. Various dimensions and dimensional ratios of the flow channel member 7 are arbitrary. The size in plan view may be set, for example, so that a desired number and density (described later) of nozzles 9 can be achieved. The thickness of the flow channel member 7 may be, for example, 0.5 mm or more and 2 mm or less.

[0050] As previously described, the flow channel member 7 has a plurality of nozzles 9. The plurality of nozzles 9 are arranged so that their positions in the D1 direction are different from each other. Therefore, by discharging ink droplets from the plurality of nozzles 9 while the transport device 25 moves the head 3 and the media P relative to each other in the D2 direction, any two-dimensional image is formed. The plurality of nozzles 9 may be arranged two-dimensionally as in the illustrated example, or they may be arranged one-dimensionally as in the illustrated example.

[0051] The specific size, number, pitch, and arrangement pattern of the multiple nozzles 9 can be set as appropriate. Figure 3 is a schematic diagram, so the nozzles 9 are shown to be large relative to the size of the head body 5, and the number of nozzles 9 on one head body 5 is shown to be small. In general, the nozzles 9 are smaller and the number of nozzles 9 is larger than in the illustrated example. For example, the number of nozzles 9 on one head body 5 may be between 100 and 10,000. Also, for example, one head body 5 may have multiple nozzles 9 with a pitch and arrangement pattern such that the dot density in the D1 direction is between 300 dpi and 2400 dpi when viewed in the D2 direction.

[0052] As shown in Figure 4, the flow channel member 7 is constructed by laminating, for example, a plurality of plates 35 (35A to 35J) via an adhesive (not shown). Holes (through holes and recesses) are formed in the plurality of plates 35, and the flow channel 13 described above is formed by the connection of the plurality of holes. The plates 35 are, for example, flat plates. The shape and size of the outer edge of the plates 35 are approximately the same as the shape and size of the outer edge of the flow channel member 7 (described above). The number of layers and thickness of the plates 35 are arbitrary. For example, the thickness may be 10 μm or more and 300 μm or less. The material of the plates 35 is also arbitrary and may be, for example, metal, resin, or ceramic.

[0053] The flow path 13 can have various configurations, and for example, it may be a known configuration. In the example shown in Figure 4, it is as follows.

[0054] The flow path 13 has at least one common flow path 37 (see also Figure 3) and a plurality of individual flow paths 39 (one is shown in Figure 4) connected to each common flow path 37. Each individual flow path 39 has a nozzle 9, and in order from the common flow path 37 to the nozzle 9, there is a supply path 41, a pressure chamber 15, and a descender 43.

[0055] Multiple individual channels 39 and a common channel 37 are filled with liquid. As the volume of the multiple pressure chambers 15 changes and pressure is applied to the liquid, the liquid is sent from the multiple pressure chambers 15 to the multiple descenders 43, and multiple droplets are discharged from the multiple nozzles 9. In addition, the multiple pressure chambers 15 are replenished with liquid from the common channel 37 via multiple supply paths 41.

[0056] The number of common channels 37 is arbitrary; there may be one or multiple (as in the example in Figure 3). Multiple common channels 37 may, for example, extend in a straight line parallel to each other. The direction in which the multiple common channels 37 extend is arbitrary; for example, they may be along the D1 direction (parallel to or inclined with respect to the D1 direction) or along the D2 direction (as in the example in Figure 3). Multiple common channels 37 may or may not merge upstream to form a manifold. The shape and various dimensions of the common channels 37 may be set as appropriate. In the example in Figure 4, the cross-sectional shape of the common channel 37 is rectangular.

[0057] Multiple individual channels 39 are arranged along each common channel 37 (in the longitudinal direction of the common channel 37). That is, multiple nozzles 9 (and multiple pressure chambers 15) are arranged along the common channel 37. The configuration of the multiple individual channels 39 is basically the same as that of each other. In Figure 3, the multiple nozzles 9 connected to one common channel 37 are arranged in one row on each side of the common channel 37, for a total of two rows. Unlike the illustrated example, the number of rows of multiple nozzles 9 connected to one common channel 37 may be other than two (for example, one or four).

[0058] As described above, the orientation of the common flow path 37 is arbitrary, and the number of rows of pressure chambers 15 (nozzles 9) connected to the common flow path 37 is also arbitrary. Therefore, the arrangement of the multiple individual actuators 17A corresponding to the multiple pressure chambers 15 shown in Figure 6 does not match the arrangement of the common flow path 37 and the multiple nozzles 9 in Figure 3. The D4 direction and D5 direction in Figure 6 may coincide with either the D1 direction or the D2 direction in Figure 1, or they may not coincide (they may be inclined).

[0059] The pressure chamber 15 is located, for example, above the common flow path 37. As already mentioned, the pressure chamber 15 opens onto the upper surface (pressure surface 7b) of the flow path member 7 and is closed by the piezoelectric actuator 11. The pressure chamber 15 may also be closed by a relatively thin plate 35. The piezoelectric actuator 11 may be placed on top of the thin plate 35. The pressure chamber 15 is formed in a thin shape that extends along the pressure surface 7b with a constant thickness. The planar shape of the pressure chamber 15 may be a suitable shape such as a rhombus, circle, or ellipse.

[0060] The descender 43 extends from the pressure chamber 15 toward the discharge surface 1a. The nozzle 9 opens into a part of the bottom surface of the descender 43 (the surface opposite to the pressure chamber 15). The supply passage 41 extends from, for example, any position in the common passage 37 (the top surface in Figure 4) and is connected to the pressure chamber 15. The specific dimensions of each part in the passage 13 are arbitrary. For example, the diameter of the pressure chamber 15 may be 200 μm or more and 400 μm or less.

[0061] Unlike the illustrated example, the pressure chamber 15 may be located, for example, to the side of the common flow path 37. Also, for example, the descender 43 may not be provided, and the nozzle 9 may open on the lower surface of the pressure chamber 15. In addition, unlike the description of the embodiment, the combination of the descender 43 and the pressure chamber 15 may be considered as the pressure chamber.

[0062] (3. Piezoelectric Actuator) (3.1. First Example) (3.1.1. General Piezoelectric Actuators) The piezoelectric actuator 11 is, for example, a roughly plate-shaped structure with an area that spans multiple (all) pressure chambers 15. Its planar shape and dimensions are, as previously described, slightly smaller than, for example, the flow channel member 7. The thickness of the piezoelectric actuator 11 is arbitrary and may be, for example, 20 μm or more and 100 μm or less.

[0063] The piezoelectric actuator 11 according to the first example shown in Figures 6 to 8 has piezoelectric layers 21A to 21D and electrodes 23A to 23F, as previously described. The piezoelectric actuator 11 may further have (or may not have) the following components: - Piezoelectric layer 21E (an example of an insulating layer): Interposed between the second constituent layer 19B and the flow channel member 7. - Upper insulating layer (not shown): For example, made of solder resist, it covers the piezoelectric layer 21A from above the electrode 23A. - Reorientation electrode (not shown): Does not drive the piezoelectric actuator 11, but contributes to the polarization of the piezoelectric layer 21.

[0064] The piezoelectric layer 21E is not sandwiched between the electrodes 23 and is not driven. Therefore, its material does not have to be a piezoelectric material. If it is not a piezoelectric material, the material can be an inorganic material (for example, SiO ２ ) or an organic material (for example, resin) may be used. Also, since the bottom electrode 23F may be given a ground potential, it is possible to directly superimpose the piezoelectric layer 21D onto the flow channel member 7 without providing the piezoelectric layer 21E. In describing the embodiments, we will take as an example an embodiment in which the piezoelectric layer 21E is provided.

[0065] (3.1.2. Active Regions of the Central Piezoelectric Section and Peripheral Piezoelectric Section) (3.1.2.1. Overview of the Active Region) As previously described, the central piezoelectric section 19AC is composed of alternatingly overlapping piezoelectric layers 21 (21A and 21B) and electrodes 23 (electrodes 23A to 23C). Of the piezoelectric layers 21, the region that is driven when an electric field is applied (the piezoelectric material of the central piezoelectric section 19AC) is, for example, the portion sandwiched between the overlapping regions of electrodes 23 that are adjacent to each other in the stacking direction (the region hatched in Figure 7). This region is sometimes referred to as the active region (reference numeral omitted). Conversely, of the piezoelectric layers 21, the portion other than the above is the piezoelectric material of the peripheral non-driven section 19AP and is sometimes referred to as the inactive region (reference numeral omitted).

[0066] Similarly, among the piezoelectric layers 21C and 21D constituting the peripheral piezoelectric portion 19BP, the region that is driven when an electric field is applied (the piezoelectric material of the peripheral piezoelectric portion 19BP) is, for example, the portion sandwiched between the overlapping regions of adjacent electrodes 23 in the stacking direction. This region is sometimes referred to as the active region. Conversely, among the piezoelectric layers 21, the portion other than the above is the piezoelectric material of the central non-driven portion 19BC and is sometimes referred to as the inactive region.

[0067] In the example shown in Figure 7, the multiple (two-layer) active regions constituting the central piezoelectric section 19AC are given the same shape (including dimensions). However, they may be different. The same applies to the peripheral piezoelectric section 19BP. The explanation regarding the planar shape of the active regions described later may be valid when the entire set of active regions is considered as a single active region, or it may be valid for each active region of the piezoelectric layer 21, as long as no contradictions arise.

[0068] The active region is, for example, polarized in the thickness direction (D3 direction), and an electric field in the polarization direction or the opposite direction is applied when the droplet is ejected. The inactive region is, for example, not polarized. Alternatively, the inactive region is polarized, but no electric field in either the polarization direction or the opposite direction is applied when the droplet is ejected. Note that a polarized region is, for example, a region in which the direction of spontaneous polarization has been aligned to some extent by a polarization treatment.

[0069] In polarization processing, electrodes 23 to which a voltage is applied for liquid discharge are often used. Therefore, the overlapping regions of adjacent electrodes 23 in the stacking direction often coincide with the polarized regions. In the description of embodiments, this embodiment may be assumed without further explanation for convenience. Contrary to the above, for example, electrodes 23 may be arranged on a piezoelectric layer 21 that has been pre-polarized. Also, for example, polarization of the inactive region may be performed by a re-orienting electrode (not shown).

[0070] As shown by the white arrows in Figure 7, in both the central piezoelectric section 19AC and the peripheral piezoelectric section 19BP, adjacent piezoelectric layers 21 in the stacking direction have their polarization directions opposite to each other. Furthermore, adjacent piezoelectric layers 21B and 21C at the stacking direction boundary between the central piezoelectric section 19AC and the peripheral piezoelectric section 19BP also have their polarization directions opposite to each other.

[0071] Therefore, for example, by applying a constant potential (e.g., ground potential) to electrodes 23 (23A and 23F) that are spaced alternately from the common electrode 23Y, and inputting a fluctuating potential (driving signal) to the other electrodes 23 (23B and 23E), multiple active regions can be contracted (or expanded) together. However, the direction of polarization and / or the applied potential may be other than those described above.

[0072] It is clear that the same principle applies even if the polarization directions shown in Figure 7 are all reversed. Also, in Figure 7, for convenience, the layer of electrode 23 to which a constant potential is applied is marked with the symbol "G", and the layer of electrode 23 to which the drive signal is input is marked with the symbol "+". Similarly, in Figure 8, the symbols "G" and "+" are used. However, the constant potential is not limited to the ground potential. Also, the drive signal may be positive or negative with respect to the ground potential. The same applies to the other drawings. However, in the description of the embodiments, for convenience, the polarization directions and potentials exemplified in Figure 7 may be assumed without further explanation.

[0073] (3.1.2.2. Planar shape of the active region) The active region of the central piezoelectric section 19AC overlaps with the center of the pressure chamber 15 and does not overlap with the inner peripheral edge of the pressure chamber 15. The center here may be, for example, the geometric center of the upper surface of the pressure chamber 15. In a planar perspective view, the active region of the peripheral piezoelectric section 19BP surrounds, for example, the active region of the central piezoelectric section 19AC. More specifically, for example, the former surrounds the latter all around. However, the former does not have to surround the latter all around. For example, the former may surround the latter in a range of 270° or more and less than 360° around its center.

[0074] In a planar perspective view, the outer edge portion of the active region of the central piezoelectric section 19AC and the inner edge portion of the active region of the peripheral piezoelectric section 19BP may be separated from each other, adjacent to each other, or overlapping (example in Figure 7). The outer edge of the active region of the peripheral piezoelectric section 19BP may be located inward, coincide with, or outward from the edge of the upper surface of the pressure chamber 15 (example in Figure 7). Each of the above embodiments may, for example, be established around the entire circumference of the center of the pressure chamber 15. However, the above embodiments may differ from each other in parts in the circumferential direction.

[0075] In a plan view, the shape of the upper surface of the pressure chamber 15, the shape of the outer edge of the active region of the central piezoelectric element 19AC, and the shapes of the inner and outer edges of the active region of the peripheral piezoelectric element 19BP (two or more of these) may be identical or similar to each other, or they may be completely different. The term "similarity" here includes, but is not limited to, the mathematical definition of similarity. For example, an ellipse and a shape having an outer edge located approximately a certain distance inward or outward from the outer edge of the ellipse are not similar in the mathematical sense, but are included in the definition of similarity in this disclosure.

[0076] The size of the active regions of the central piezoelectric section 19AC and the peripheral piezoelectric section 19BP in a plan view is arbitrary. For example, in a plan view, the area of ​​the central piezoelectric section 19AC may be 40% or more, 50% or more, or 90% or less, 80% or less, or 70% or less of the area of ​​the pressure chamber 15, and the above lower and upper limits may be combined in any way.

[0077] Furthermore, in a configuration where the active region of the central piezoelectric section 19AC and the active region of the peripheral piezoelectric section 19BP overlap, for example as shown in Figure 7, the distance over which they overlap may be 10% or less (or 5% or less) of the diameter of the central piezoelectric section 19AC, or 10% or more, in any horizontal direction passing through the center of the pressure chamber 15. Also, in a configuration where the outer edge of the active region of the peripheral piezoelectric section 19BP is located outside the outer edge of the pressure chamber 15, for example as shown in Figure 7, the distance between them is also arbitrary.

[0078] (3.1.3. Piezoelectric Layer) In this embodiment, the piezoelectric layer 21 refers to, for example, a layer of piezoelectric material sandwiched between electrodes 23 for driving the central piezoelectric portion 19AC and / or peripheral piezoelectric portion 19BP. Therefore, even if the piezoelectric layer 21 sandwiched between electrodes 23A and 23B is a laminate consisting of multiple layers of piezoelectric material in terms of material and / or manufacturing method, the piezoelectric layer 21 located between electrodes 23A and 23B is a single layer.

[0079] The piezoelectric layer 21 is generally spread in a planar manner with a constant thickness; in other words, it is generally flat. Its area is generally equivalent to the area of ​​the piezoelectric actuator 11. The thickness of the piezoelectric layer 21 may be set as appropriate. Multiple piezoelectric layers 21 may have the same thickness or different thicknesses. An example of the thickness of the piezoelectric layer 21 is 3 μm to 40 μm.

[0080] In the example shown in Figure 7, the total thickness of piezoelectric layers 21A and 21B (which may or may not include the thickness of the electrode 23 interposed between them; the same applies to other total thicknesses below) is greater than the total thickness of piezoelectric layers 21C and 21D. The former and the latter can be considered as the thickness of the active region of the central piezoelectric section 19AC and the active region of the peripheral piezoelectric section 19BP, respectively. The difference between the two thicknesses is arbitrary. For example, the former may be 1.2 times or more, or 1.5 times or more, or 3.0 times or less, or 2.5 times or less, and the above lower and upper limits may be any combination.

[0081] Furthermore, in the example shown in Figure 7, the combined thickness of piezoelectric layers 21A and 21B is greater than the combined thickness of piezoelectric layers 21C to 21E. The former and the latter can be considered as the thickness above and below the common electrode 23Y, respectively. The difference between the two thicknesses is arbitrary. For example, the former may be 1.1 times or more, or 1.3 times or more, or 2.0 times or less, or 1.6 times or less, and the above lower and upper limits may be any combination.

[0082] Furthermore, in the example shown in Figure 7, the thicknesses of piezoelectric layers 21A and 21B are greater than the thicknesses of piezoelectric layers 21C to 21E. The difference in thickness between the two is arbitrary. For example, the former may be 1.2 times or more, or 1.5 times or more, or 4.0 times or less, 3.0 times or less, or 2.5 times or less than the latter, and the above lower and upper limits may be any combination.

[0083] In the example shown in Figure 7, the thicknesses of piezoelectric layers 21A and 21B are the same. Similarly, the thicknesses of piezoelectric layers 21C and 21D are the same. The thickness of each piezoelectric layer 21C and 21D is slightly greater than the thickness of piezoelectric layer 21E. For example, the former may be 1.1 times or more, or 1.2 times or more, or 2.0 times or less, or 1.5 times or less than, and the above lower and upper limits may be any combination.

[0084] The material of the piezoelectric layer 21 may be, for example, a ferroelectric ceramic material. Examples of ceramic materials include lead zirconate titanate (PZT)-based materials and NaNbO ３ system, BaTiO ３ System, (BiNa)TiO ３ System, BiNaNb ５ O １５ Examples of such systems can be given. However, the material of the piezoelectric layer 21 may be something other than a ceramic material. The material of the piezoelectric layer 21 may be a single crystal, a polycrystalline material, an inorganic material, an organic material, a ferroelectric material or not, or a pyroelectric material or not. The materials of multiple piezoelectric layers 21 may be the same as or different from each other.

[0085] (3.1.4. Conductors) The material of the conductors (e.g., electrodes 23, wiring and via conductors described later) of the piezoelectric actuator 11 may be, for example, an appropriate metal material. The materials of the conductor layers (e.g., electrodes 23 and wiring described later) located in different layers (different boundaries of the plurality of piezoelectric layers 21) may be the same or different. A single conductor layer may be integrally constructed from one type of material, or it may be constructed by laminating different materials. The material of a single conductor layer is the same at different positions in the planar direction. However, the material of some areas may be different from the material of other areas.

[0086] The conductive layer, including the electrodes 23, is generally spread out in a planar manner with a constant thickness. The thickness of the conductive layer is arbitrary. However, typically, the thickness of the conductive layer is thinner than the thickness of the piezoelectric layer 21. Also, the thicknesses of multiple conductive layers may be the same or different. An example of a conductive layer thickness is 0.5 μm to 3 μm.

[0087] A flexible substrate (not shown) is positioned opposite the upper surface of the piezoelectric actuator 11. A conductor (specific portion of the conductor layer or via conductor) exposed on the uppermost layer of the piezoelectric actuator 11 is joined to a pad located on the lower surface of the flexible substrate via a bump (solder, etc.). As a result, the piezoelectric actuator 11 is electrically connected to the driver 49 and supplied with a drive signal and ground potential.

[0088] (3.1.5. Electrodes) As previously described, the planar shape (including dimensions) of the active region is determined by the shape of the overlapping regions of electrodes 23 that are adjacent to each other in the stacking direction. Therefore, the planar shape of the electrodes 23 may be set appropriately so as to realize the planar shape of the active region described above. In the examples of Figures 6 to 8, this is as follows.

[0089] The multiple electrodes 23A are separated from each other, for example, in terms of their shape. In another respect, there is a region where no conductor is placed between adjacent electrodes 23A. That is, in terms of shape, the electrodes 23A are individual electrodes. However, as previously described, the multiple electrodes 23A may be assigned a constant (common) potential, similar to the common electrode 23Y. In the illustrated example, the multiple electrodes 23A are electrically connected to each other and assigned the same potential. That is, in terms of potential, the multiple electrodes 23A are not individual electrodes.

[0090] The multiple electrodes 23B are so-called individual electrodes. That is, the multiple electrodes 23B are separated from each other in terms of their shape and electrical properties. Furthermore, it is possible to apply different potentials (driving signals) to the multiple electrodes 23B.

[0091] The electrode 23B includes, for example, an electrode body 23a that contributes to applying a voltage to the active region, and a lead-out portion 23b for inputting a drive signal to the electrode body 23a. The lead-out portion 23b extends outward from the electrode body 23a that overlaps the pressure chamber 15. Its direction of extension is arbitrary; for example, it may be perpendicular, parallel, or inclined to the direction of alignment of the pressure chambers 15 (direction D4 or direction D5).

[0092] Contrary to the above description, the electrode body 23a may be considered as the electrode 23B, and the lead-out portion 23b may be considered as wiring. In the description of the embodiment, the shape of the electrode 23B may be described without regard to the lead-out portion 23b unless otherwise specified.

[0093] The electrodes 23A and 23B (excluding the lead-out portion 23b) may be identical in shape and dimensions, or they may be different in shape and / or dimensions. In the latter case, either electrode 23 may define the planar shape (including dimensions) of the active region of the piezoelectric layer 21A. In some parts of the outer edge of the active region, the electrodes 23 defining the outer edge may be different. In either case, the previously described explanation of the planar shape of the central piezoelectric portion 19AC may be applied to electrodes 23A and / or 23B.

[0094] In the examples shown in Figures 6 to 8, the outer edge of electrode 23A is located outside the outer edge of electrode 23B (excluding the lead portion 23b) along its entire circumference. The planar shape of the active region of the piezoelectric layer 21A is defined by electrode 23B. In this case, the distance between the two is arbitrary. For example, the distance between them may be 1.1 times or more, or 1.2 times or more, the diameter of electrode 23B in any horizontal direction passing through the center of electrode 23B. Also, in a planar perspective view, the outer edge of electrode 23A may be located inside the outer edge of the pressure chamber 15 (as shown in the example), coincide with it, or outside.

[0095] Multiple electrodes 23C are composed of regions of the common electrode 23Y, which extends in a planar (solid) shape, that overlap with multiple electrodes 23B. In other words, the region of the common electrode 23Y that overlaps with the active region of the piezoelectric layer 21B is electrode 23C.

[0096] Furthermore, electrodes 23A and 23B, which are separate electrodes in terms of shape, may be considered as a whole component of the central piezoelectric section 19AC. From another viewpoint, for example, the portion of electrode 23A located outside the active region of the piezoelectric layer 21A may also be considered as part of electrode 23A. However, contrary to the description of the embodiment, only the region that is in contact with its upper or lower surface and overlaps with the active region of the central piezoelectric section 19AC may be considered as a component of the central piezoelectric section 19AC. The same applies to the peripheral piezoelectric section 19BP.

[0097] Multiple electrodes 23D are composed of regions of the common electrode 23Y that spread out in a solid shape and overlap with multiple electrodes 23E. In other words, the region of the common electrode 23Y that overlaps with the active region of the piezoelectric layer 21C is electrode 23D.

[0098] In the example shown in Figure 7, the outer peripheral portion of the active region of the piezoelectric layer 21B and the inner peripheral portion of the active region of the piezoelectric layer 21C overlap. Consequently, the outer peripheral portion of electrode 23C and the inner peripheral portion of electrode 23D are shared by these electrodes. When electrodes 23C and 23D are said to be connected to each other to form a shared electrode 23Z, this shared configuration is included in the configuration of being connected to each other.

[0099] The multiple electrodes 23E are so-called individual electrodes. The description of electrode 23B may be applied to electrode 23E unless contradictions arise. However, unlike electrode 23B, electrode 23E has an opening (not shown) in the electrode body 23a that overlaps the center of the pressure chamber 15. In other words, electrode body 23a is configured in an annular shape so as not to overlap the center of the pressure chamber 15. This opening defines the inner edge of the active region of the peripheral piezoelectric part 19BP. Also, the outer edge of electrode 23E is located outside the outer edge of electrode 23B (in other words, the active region of the central piezoelectric part 19AC). Note that, unlike the illustrated example, electrode body 23a may be C-shaped, for example.

[0100] Electrodes 23B and 23E, which correspond to the same pressure chamber 15, have, for example, lead-out portions 23b extending in the same direction. This makes it easy to connect them, for example, by vias 47, which will be described later. Of course, the lead-out portions 23b of both electrodes may extend in different directions.

[0101] The multiple electrodes 23F are individual electrodes in terms of shape, similar to electrode 23A, but not individual electrodes in terms of electricity. The description of electrode 23A may be applied to electrode 23E, provided that no contradictions arise. However, the specific shape (including dimensions) of electrode 23F may differ from that of electrode 23A, for example.

[0102] The outer edges of electrode 23E (excluding the lead-out portion 23b) and electrode 23F may be identical in shape and dimensions, or they may be different in shape and / or dimensions. In the latter case, either electrode 23 may define the outer edge of the active region of the piezoelectric layer 21D. The electrodes 23 defining the outer edges of different parts of the outer edges of the active region may be different. In either case, the previously described explanation regarding the shape and / or dimensions of the outer edge of the peripheral piezoelectric portion 19BP may be applied to the outer edges of electrode 23E and / or 23F.

[0103] In the examples shown in Figures 6 to 8, the outer edge of electrode 23F is located outside the outer edge of electrode 23E (excluding the lead-out portion 23b) throughout its entire circumference. The outer edge of the active region of the piezoelectric layer 21D is defined by electrode 23E. In this case, the distance between the two is arbitrary. For example, the distance between them may be 1.1 times or more, or 1.2 times or more, the diameter of electrode 23E in any horizontal direction passing through the center of electrode 23E (ignoring the opening).

[0104] The multi-purpose electrode 23Z includes electrodes 23C and 23D. In the illustrated example, the outer peripheral portion of electrode 23C (active region of piezoelectric layer 21B) and the inner peripheral portion of electrode 23D (active region of piezoelectric layer 21C) overlap, so the multi-purpose electrode 23Z has a shape that eliminates the opening from electrode 23D (23E). If the outer edge of electrode 23C and the inner edge of electrode 23D are separated, the multi-purpose electrode 23Z includes a portion located between them that connects them. This portion may or may not fill the entire gap between the outer edge of electrode 23C and the inner edge of electrode 23D.

[0105] The common electrode 23Y includes multiple shared electrodes 23Z and, in the illustrated example, is spread out in a solid form. A solid form is, for example, a pattern that spreads over a relatively wide area with virtually no gaps. Also, for example, the shape of its outer edge may follow the shape of the outer edge of the piezoelectric layer 21 (21B and / or 21C) on which the common electrode 23Y overlaps, or it may be a simple shape (rectangular, etc.) that does not produce any particular effect. The solid form pattern may have relatively small holes (including notches on the outer edge). For example, as shown in Figures 6 and 8, the solid form pattern may have holes for passing vias that have a different potential from the common electrode 23Y. Assuming there are no holes for vias, the common electrode 23Y may occupy, for example, 80% or more of the area of ​​the piezoelectric layer 21B or 21C.

[0106] (3.1.6. Connection of electrodes) The multiple electrodes 23A are electrically connected to each other as described above. The multiple electrodes 23F are also electrically connected to each other. The configuration of these connections is arbitrary.

[0107] In the examples shown in Figures 6 and 8, the multiple electrodes 23A are connected to each other by wiring 45A (linear conductor patterns) located in the same layer as the multiple electrodes 23A. Similarly, the multiple electrodes 23F are connected to each other by wiring 45F located in the same layer as the multiple electrodes 23F. In the following, wiring 45A and 45F may be referred to collectively as wiring 45 without distinction.

[0108] The number, position, shape, and dimensions of the multiple wires 45 can be set as appropriate. For example, the wires 45 may connect adjacent electrodes 23 in the D5 direction (example in Figure 6), or they may connect adjacent electrodes 23 in directions other than the D5 direction (the D4 direction or a direction inclined towards the D4 direction), or they may be connections that combine two or more of these connections. Also, for example, the wires 45 may extend in a straight line (example shown), or they may be bent or curved.

[0109] In the example shown in Figure 6, the wiring 45 extends linearly in a direction that intersects (more specifically, perpendicular to) the direction in which the lead-out portions 23b of electrodes 23B and 23E extend. Consequently, the wiring 45 and the lead-out portions 23b do not overlap. Furthermore, the wirings 45A and 45F extend in the same direction. These features facilitate connections, for example, by vias 47, which will be described later. For clarification, it is also possible to extend the lead-out portions 23b and the wiring 45 in the same direction, and it is also possible to extend the wirings 45A and 45F in different directions.

[0110] Furthermore, for example, the wiring 45 may have a substantially constant width along its length (as shown in the illustration), or its width may vary depending on its position along its length. The width of the wiring 45 (for example, the maximum width or average width along its entire length or at 80% of its total length) is smaller than the diameter of the electrodes 23 in the width direction of the wiring 45, such that gaps are formed between the electrodes 23 (so that the electrodes 23 become individual electrodes in terms of shape). For example, the former may be 1 / 2, 1 / 3, or 1 / 4 of the latter.

[0111] As previously described, the common electrode 23Y is electrically connected to the alternate electrodes 23 (23A and 23F). The other alternate electrodes 23 (23B and 23E) are also electrically connected to each other. The configuration of these connections is arbitrary.

[0112] As can be seen from the dashed lines connecting the vias 47 on the left side of Figure 8, in the examples of Figures 6 and 8, electrodes 23A, 23F, and 23Y are connected to each other by vias 47 that penetrate the piezoelectric layer 21 at the location of the wiring 45. In each piezoelectric layer 21, a via 47 is provided for every two electrodes 23A (and similarly for electrode 23F). Furthermore, the vias 47 of multiple piezoelectric layers 21 are located at the same position to each other in a planar perspective view, for example.

[0113] Unlike the illustrated example, in each piezoelectric layer 21, vias 47 may be provided one or more times for each electrode 23A (23F), or for every three or more electrodes 23A, or in a manner in which such distinctions cannot be made. Also, for example, in each layer, wiring may be provided that extends from a row of electrodes 23 (in the D5 direction) connected to each other by wiring 45 to the -D5 side and / or the +D5 side, and merging wiring may be provided that connects the above wirings corresponding to the row, and the merging wirings may be connected by one or more vias 47. Also, for example, the positions of the vias 47 in multiple piezoelectric layers 21 may differ from each other in a planar perspective view. Also, for example, some or all of the vias 47 may be provided in a position that overlaps with the electrodes 23.

[0114] As can be seen from the dashed line connecting the vias 47 on the right side of Figure 8, in the examples of Figures 6 and 8, electrodes 23B and 23E are connected to each other by vias 47 that penetrate the piezoelectric layer 21 at the position of the lead-out portion 23b. In each piezoelectric layer 21, vias 47 are provided in a one-to-one ratio with respect to electrodes 23B (23E).

[0115] The specific configuration of via 47 is arbitrary. The upper end of the conductor of via 47 may, for example, be in contact with the lower surface of the wiring 45 (conductor layer), or it may penetrate the conductor layer. Alternatively, such a distinction may not be possible. The same applies to the lower end of the conductor. In Figure 8, for illustrative purposes, hatching is applied to make it appear as if the conductor of via 47 penetrates the conductor layer. Also, although there is no via 47 below wiring 45F, hatching is applied to the position of the lower end of the upper via 47 for illustrative purposes.

[0116] (3.1.7. Operation) The driving method of the individual actuators 17 when applying pressure to the pressure chamber 15 can be various, for example, a known method or an application of a known method. For example, a so-called pull-and-drive or push-and-drive method may be adopted. In any driving method, basically, the individual actuator 17 transitions from a standby state before discharge to a driving state for discharge, and then returns to the standby state. In the driving state, compared to the standby state, both the central piezoelectric part 19AC and the peripheral piezoelectric part 19BP may extend (or both may contract). The specific operation, taking the pull-and-drive method as an example, is as follows.

[0117] - Standby state: The driver 49 applies a potential higher than the ground potential (the potential of electrode 23A, the common electrode 23Y, and electrode 23F) to electrodes 23B and 23E. As a result, both the central piezoelectric part 19AC and the peripheral piezoelectric part 19BP are contracted, resulting in the state illustrated in Figure 5. In other words, the individual actuators 17 are in a state where they have undergone deflection deformation toward the pressure chamber 15.

[0118] - Driving state (start): When it is time to discharge the droplets, the driver 49 applies a ground potential to electrodes 23B and 23E. As a result, both the central piezoelectric part 19AC and the peripheral piezoelectric part 19BP are released from contraction (extend). The individual actuators 17 then begin to return to a flat state, and consequently, the volume of the pressure chamber 15 begins to increase. From another perspective, the individual actuators 17 begin to vibrate at their natural frequencies.

[0119] - Driving state (continued): After the above, the volume of the pressure chamber 15 reaches its maximum and then decreases again. As the volume decreases, the pressure in the pressure chamber 15 increases. Then, at the moment when the pressure is approximately at its maximum, a potential higher than the ground potential is applied to electrodes 23A and 23E. As a result, both the central piezoelectric part 19AC and the peripheral piezoelectric part 19BP contract. Then, the first applied vibration and the second applied vibration overlap, and a larger pressure is applied inside the pressure chamber 15.

[0120] - Return to standby state: As described above, in the driving state, electrodes 23B and 23E are first given a ground potential, and then a potential higher than the ground potential is given. This potential is, for example, the same as the potential in the standby state. In other words, in the driving state, the driver 49 inputs a pulsed driving signal to electrodes 23B and 23E that is at a low potential for a certain period of time, with a potential higher than the ground potential as the reference. After the above period of time has elapsed, the individual actuators 17 return to the standby state.

[0121] The driver 49, for example, changes the amplitude of the pulsed drive signal and / or the number of drive signals according to the size of the dot to be formed on the recording medium. This results in larger droplets being ejected, or two or more droplets being ejected for a single dot.

[0122] As can be understood from the above explanation, when a droplet is ejected, the change in voltage applied to the central piezoelectric part 19AC and the change in voltage applied to the peripheral piezoelectric part 19BP are the same. Therefore, the period during which the central piezoelectric part 19AC extends and the period during which the peripheral piezoelectric part 19BP extends are the same, and the period during which the central piezoelectric part 19AC contracts and the period during which the peripheral piezoelectric part 19BP contracts are the same. To put it in broader terms, the period during which the central piezoelectric part 19AC undergoes either extension or contraction and the period during which the peripheral piezoelectric part 19BP undergoes either extension or contraction overlap in at least part.

[0123] As can be understood from the explanation of the pull-and-run method, the period during which one of the contraction and expansion occurs is not limited to the period during which voltage is actively applied to the central piezoelectric section 19AC and the peripheral piezoelectric section 19BP. For example, the period during which one of the contraction and expansion occurs may be the period during which the potentials of electrodes 23B and 23E are set to ground potential when the timing for droplet discharge arrives. This period can be considered as the period during which no voltage is applied to the central piezoelectric section 19AC and the peripheral piezoelectric section 19BP. However, in any case, the driver 49 controls the strength of the electric field applied to the central piezoelectric section 19AC and the strength of the electric field applied to the peripheral piezoelectric section 19BP in liquid discharge control such that the peripheral piezoelectric section 19BP experiences one of the contraction and expansion for at least a portion of the period during which the central piezoelectric section 19AC experiences one of the contraction and expansion.

[0124] Unlike the embodiment, it is also possible to stagger the periods during which voltage is applied between the central piezoelectric section 19AC and the peripheral piezoelectric section 19BP. For example, electrodes 23B and 23E, which correspond to the same pressure chamber 15, may not be connected to each other, and drive signals may be input to electrodes 23B and 23E at different timings.

[0125] (3.2. Second Example) Figure 9 is a cross-sectional view showing individual actuator 17B as a specific example (second example) of individual actuator 17, and corresponds to Figure 7. Also, Figure 10 is an exploded perspective view of individual actuator 17B, and corresponds to Figure 8.

[0126] The individual actuator 17B differs from the individual actuator 17A in that an opening (not shown in the reference numeral) is formed in the electrode 23F. That is, in the individual actuator 17B, the electrode 23F is annular, similar to the electrode 23E.

[0127] The inner edges of electrodes 23E and 23F may be identical in shape and dimensions, or they may be different in shape and / or dimensions. In the latter case, the inner edge of either electrode 23 may define the inner edge of the active region. The electrodes 23 defining the inner edges of the active region may differ for parts of the inner edge. In either case, the previously described explanation regarding the shape of the inner edge of the peripheral piezoelectric portion 19BP may be applied to the inner edges of electrodes 23E and / or 23F.

[0128] In the examples of Figures 9 and 10, the inner edge of electrode 23F is located inside the inner edge of electrode 23E throughout its entire circumference. The inner edge of the active region is defined by electrode 23E. In this case, the distance between the two is arbitrary. For example, the distance between them may be 1.1 times or more, or 1.2 times or more, the diameter of electrode 23E in any horizontal direction passing through the center of electrode 23E (ignoring the opening).

[0129] (3.3. Third Example) Figure 11 is a cross-sectional view showing an individual actuator 17C as a specific example (third example) of an individual actuator 17, and corresponds to Figure 7.

[0130] The individual actuator 17C differs from the individual actuator 17A in the relative thickness of the multiple piezoelectric layers 21. Specifically, in the individual actuator 17C, the thicknesses of the piezoelectric layers 21A to 21D are the same. From another perspective, the thickness of the active region of the central piezoelectric section 19AC and the thickness of the active region of the peripheral piezoelectric section 19BP are the same.

[0131] The relationship between the thickness above the common electrode 23Y and the thickness below the common electrode 23Y is the opposite to that of the individual actuator 17A, with the latter being thicker than the former. The difference between the two is arbitrary. For example, the latter may be 1.1 times or more, or 1.2 times or more, or 1.5 times or less, or 1.3 times or less, and the above lower and upper limits may be any combination.

[0132] The thickness of each piezoelectric layer 21A to 21D is, for example, greater than the thickness of piezoelectric layer 21E. For example, the former may be 1.2 times or more, or 1.5 times or more, or 3.0 times or less, or 2.5 times or less than, the lower and upper limits may be any combination.

[0133] (3.4. Fourth Example) Figure 12 is a cross-sectional view showing an individual actuator 17D as a specific example (fourth example) of an individual actuator 17, and corresponds to Figure 7.

[0134] The individual actuator 17D differs from the individual actuator 17C in that an opening (not shown in the reference numeral) is formed in the electrode 23F. The description of the electrode 23F of the individual actuator 17B may be applied to the description of the electrode 23F of the individual actuator 17D.

[0135] (3.5. Fifth Example) Figure 13 is a cross-sectional view showing an individual actuator 17E as a specific example (fifth example) of an individual actuator 17, and corresponds to Figure 7.

[0136] The individual actuator 17E differs from the individual actuator 17A in that the piezoelectric layer 21 (21F) of the central piezoelectric section 19AC is a single layer. In the illustrated example, the configuration from the common electrode 23Y downwards is the same as that of the individual actuator 17A, but it may be the same as that of the individual actuator 17B (or 17C or 17D). The same applies to Figure 14 (sixth example) described later.

[0137] Regarding the thickness of the piezoelectric layer 21F, the explanation of the thickness of the piezoelectric layer 21A or 21B of the individual actuator 17A may be used, or the explanation of the total thickness of piezoelectric layers 21A and 21B (those directly stated and those derived from the explanations of each thickness) may be used. Also, unlike the illustrated example, the thicknesses of piezoelectric layers 21F, 21C, and 21D may be the same.

[0138] The electrode configuration in the central piezoelectric section 19AC may be, for example, a configuration in which the electrode 23A (and piezoelectric layer 21A) is omitted in the central piezoelectric section 19AC of the individual actuator 17A. That is, in the individual actuator 17E, the uppermost electrode 23 may be the electrode 23B of the individual actuator 17A (the individual electrode to which the drive signal is input). The position of the via 47 mediating between the common electrode 23Y and the upper surface of the piezoelectric actuator 11 may be the same as or different from that of the individual actuator 17A.

[0139] (3.6. Sixth Example) Figure 14 is a cross-sectional view showing an individual actuator 17F as a specific example (sixth example) of an individual actuator 17, and corresponds to Figure 7.

[0140] The individual actuator 17F differs from the individual actuator 17A in that the piezoelectric layer 21 (21G to 21I) of the central piezoelectric section 19AC has three layers. For the total thickness of the piezoelectric layers 21G to 21I, for example, the explanation of the total thickness of the piezoelectric layer 21A or 21B of the individual actuator 17A may be used. The thicknesses of each of the piezoelectric layers 21G to 21I may be the same (as shown in the illustration) or they may be different. Unlike the illustration, the thicknesses of the piezoelectric layers 21G to 21I, 21C and 21D may be the same.

[0141] The electrode configuration in the central piezoelectric section 19AC may be, for example, a configuration in which an electrode 23G is added on top of electrode 23A in the central piezoelectric section 19AC of the individual actuator 17A. Electrode 23G may be electrically connected to, for example, alternate electrodes 23 (electrodes 23B and 23E). That is, electrode 23G may be individual electrodes to which a drive signal is input. Although not shown in particular, vias 47 that electrically relay between the electrode 23 below and above may be provided in the piezoelectric layer 21G at appropriate positions.

[0142] (3.7. Example 7) Figure 15 is a cross-sectional view showing an individual actuator 17G as a specific example of an individual actuator 17 (Example 7), and corresponds to Figure 7.

[0143] The individual actuator 17G differs from the individual actuator 17B in that, in general, the positional relationship in a plan view of the outer edge of the central piezoelectric section 19AC, the inner and outer edges of the peripheral piezoelectric section 19BP, and the outer edge of the pressure chamber 15. The relative thickness of the piezoelectric layer 21 is the same as that of the individual actuator 17B, but it may be the same as that of the other individual actuators 17 (17D to 17F).

[0144] Specifically, in the seventh example, the outer edge of the central piezoelectric section 19AC and the inner edge of the peripheral piezoelectric section 19BP coincide in a planar perspective. From another point of view, unlike the other examples, the entire area directly beneath the central piezoelectric section 19AC in the piezoelectric layers 21C and 21D is an inactive region. Also, in the seventh example, the outer edge of the peripheral piezoelectric section 19BP coincides with the outer edge of the pressure chamber 15 in a planar perspective.

[0145] As can be understood from the above explanation, unlike the illustrated example, the relationship between overlapping, coincidental (adjacent), or separated regions may differ between the inner and outer edges of the peripheral piezoelectric portion 19BP. For example, the outer peripheral portion of the active region of the central piezoelectric portion 19AC and the inner peripheral portion of the active region of the peripheral piezoelectric portion 19BP may not overlap, while the outer peripheral portion of the active region of the peripheral piezoelectric portion 19BP may overlap with the outer portion of the pressure chamber 15 of the flow channel member 7.

[0146] (3.8. Example 8) Figure 16 is an exploded perspective view of a part of the piezoelectric actuator 11B, which is a specific example (Example 7) of the piezoelectric actuator 11, and corresponds to Figure 6.

[0147] The piezoelectric actuator 11B differs from the piezoelectric actuator 11A in that the multiple electrodes 23 (electrodes 23A and 23F), which are supplied with a ground potential and are individual electrodes in terms of shape, are not connected by wiring 45 within the same layer. This configuration may also be applied to piezoelectric actuators 11 that include individual actuators 17 (17B to 17G) other than individual actuator 17A.

[0148] More specifically, for example, each of the multiple electrodes 23A (and 23F) has a lead-out (not shown in the reference numerals). These lead-outs are connected by vias 47 to alternate electrodes 23 (including the common electrode 23Y). A ground potential is also applied to each lead-out of the multiple electrodes 23A.

[0149] In piezoelectric actuator 11A, vias 47 connecting electrodes 23A (or 23F) and a common electrode 23Y are provided in each piezoelectric layer 21 for every two electrodes 23A. From another perspective, the number of vias 47 in each piezoelectric layer 21 may be less than the number of electrodes 23A. On the other hand, in piezoelectric actuator 11B, the number of vias 47 in each piezoelectric layer 21 is equal to or greater than the number of electrodes 23A.

[0150] (4. Method for Manufacturing a Piezoelectric Actuator) The piezoelectric actuator 11 may be manufactured by various methods, including, for example, a known method. Examples are given below.

[0151] A conductive paste, which will serve as conductors (e.g., electrodes 23, wiring 45, and vias 47), is placed on a ceramic green sheet that will become the piezoelectric layer 21. Next, multiple ceramic green sheets are stacked. After that, the stack is fired. From another perspective, the ceramic green sheets and conductive paste are fired simultaneously. This forms the piezoelectric actuator 11. Note that each conductor layer (electrode 23) may be placed on the ceramic green sheet that will become the piezoelectric layer 21 located below it, or vice versa.

[0152] The uppermost conductive layer (for example, electrode 23A in the first example) may be formed after the simultaneous firing described above by placing a conductive paste and firing the laminate (baking may be performed). In this case, the piezoelectric actuator 11 may deform to become convex downwards (warp) due to the contraction of the uppermost conductive layer during firing and / or cooling after firing. Therefore, before baking, the piezoelectric actuator 11 may be configured to warp slightly upwards. Specifically, the thickness of the piezoelectric layer 21 and the shape of the electrode 23 may be set to produce such a warp.

[0153] (5. Summary of Embodiments) Below, we will extract the configuration of the embodiments and describe examples of the effects of the extracted configuration. Note that the effects described do not necessarily have to be achieved by the extracted configuration. Also, for convenience, we may only assign reference numerals to specific examples from among multiple examples (Examples 1 to 8), but the same applies to other examples unless it causes inconsistencies.

[0154] The piezoelectric actuator 11 according to this embodiment is superimposed on the pressurizing surface 7b of the flow channel member 7. The flow channel member 7 has a plurality of pressure chambers 15 arranged along the pressurizing surface 7b. The piezoelectric actuator 11 has a plurality of individual actuators 17 that pressurize each of the plurality of pressure chambers 15. Each of the plurality of individual actuators 17 has a central piezoelectric section 19AC and a peripheral piezoelectric section 19BP. The central piezoelectric section 19AC is composed of one or more piezoelectric layers 21 (example of a first piezoelectric layer) and two or more electrodes 23 (example of a first electrode) that are alternately superimposed on the side facing the pressurizing surface 7b (the opposite side being an example of a first side). The two or more electrodes 23 are superimposed on the center of the corresponding pressure chamber 15. The peripheral piezoelectric section 19BP is composed of two or more piezoelectric layers 21 (example of a second piezoelectric layer) and three or more electrodes 23 (example of a second electrode) that are alternately superimposed on the side facing the pressurizing surface 7b. The three or more electrodes 23 are superimposed on the inner peripheral edge of the corresponding pressure chamber 15. In the piezoelectric actuator 11, the side with the pressure surface 7b (first side) is referred to as the lower layer side, and the side opposite to the pressure surface 7b is referred to as the upper layer side (it does not necessarily have to be actually above or below). In this case, the lowest electrode 23 (23C) in the central piezoelectric section 19AC and the uppermost electrode (23D) in the peripheral piezoelectric section 19BP are located on the same layer (the same boundary of multiple piezoelectric layers 21) and are connected to each other to form a shared electrode 23Z. The shared electrodes 23Z of the multiple individual actuators 17 are electrically connected to each other (that is, the multiple shared electrodes 23Z are given a common potential such as ground potential). In the peripheral piezoelectric section 19BP, the number of the two or more piezoelectric layers 21 (counted with the position of the electrode 23 as the boundary position) is even, and the lowest electrode 23 (23F) is electrically connected to the shared electrode 23Z.

[0155] From another perspective, the head 3 (an example of a liquid dispensing device) according to the embodiment includes the piezoelectric actuator 11 and the flow path member 7.

[0156] From yet another perspective, the printer 1 (an example of a recording device) according to this embodiment includes the head 3 and a transport device 25. The transport device 25 moves the head 3 and the media P (an example of a recording medium) relative to each other.

[0157] Therefore, as described in the overview of the embodiment, for example, it is possible to increase the deformation amount of the piezoelectric actuator 11 with a simple and compact configuration, while reducing the influence of the electrode 23 on the ink (an example of a liquid) and reducing the likelihood of a decrease in ink ejection characteristics.

[0158] The electrodes 23F of the lowest layer in the peripheral piezoelectric portion 19BP of multiple individual actuators 17 may be connected to each other by linear wiring 45F within the same layer.

[0159] In this case, compared to a configuration in which multiple electrodes 23F are not connected by wiring 45F, such as in the piezoelectric actuator 11B (Figure 16), each electrode 23F is supplied with potential not only from the corresponding via 47 but also from other electrodes 23F. As a result, the reliability of the electrical connection for supplying ground potential to the electrodes 23F is improved. Furthermore, compared to a configuration in which multiple electrodes 23F are spread out and connected to each other to form a solid electrode (this configuration may also be included in the technology of this disclosure), the volume of the electrode 23 located on the lower side is reduced. As a result, when the piezoelectric actuator 11 is manufactured by firing, for example, the likelihood of excessive upward convexity of the piezoelectric actuator 11 is reduced.

[0160] In each of the multiple individual actuators 17, the two or more electrodes 23 in the central piezoelectric section 19AC and the three or more electrodes in the peripheral piezoelectric section 19BP may consist of a shared electrode 23Z, a plurality of third electrodes, and one or more remaining fourth electrodes. The plurality of third electrodes may be electrodes 23 that are not electrically connected to the same electrodes of other individual actuators 17, for example, electrodes 23B and 23E in the first example. The one or more remaining fourth electrodes may be electrodes 23A and 23F in the first example. Electrodes 23A and 23F may each be connected to the same electrode 23 of other individual actuators 17 by linear wiring 45 in the same layer.

[0161] In this case, compared to, for example, a piezoelectric actuator 11B in which multiple electrodes 23A (and 23F) are not connected by wiring 45, each electrode 23A is supplied with potential not only from the corresponding via 47 but also from other electrodes 23A. As a result, for example, the reliability of the electrical connection for supplying ground potential to the electrodes 23A is improved. Also, compared to, for example, a configuration in which multiple electrodes 23A (and 23F) are spread out in a solid shape and connected to each other (this configuration may also be included in the technology of this disclosure), the volume of electrodes 23 included in the piezoelectric actuator 11 is reduced. As a result, for example, when the piezoelectric actuator 11 is manufactured by firing, the probability of unintended warping occurring in the piezoelectric actuator 11 is reduced.

[0162] The shared electrodes 23Z of multiple individual actuators 17 may be spread out in a solid shape and connected to each other (a common electrode 23Y may be formed).

[0163] In this case, for example, the reliability of the electrical connection of the multiple shared electrodes 23Z can be improved compared to an embodiment in which multiple shared electrodes 23Z are connected by wiring 45 (this embodiment may also be included in the technology of this disclosure). Since the shared electrodes 23Z are located at the boundary between the central piezoelectric portion 19AC and the peripheral piezoelectric portion 19BP in the D3 direction, there is a high probability that they are located near the center of the thickness of the piezoelectric actuator 11. Therefore, even if multiple shared electrodes 23Z are made into a solid shape to improve electrical reliability, the probability of unintended warping occurring in the piezoelectric actuator 11 due to shrinkage of the solid pattern is relatively low compared to an embodiment in which other layers are made into a solid shape. Furthermore, from the following viewpoint as well, it is effective for the common electrode 23Y to be located near the center in the stacking direction. The presence of the common electrode 23Y makes it easier to keep the sintering state of the piezoelectric actuator 11 constant. One reason for this is that diffused conductive elements affect sintering. Furthermore, because conductors have a higher thermal conductivity than piezoelectric materials, the heat transferred from the conductor to the piezoelectric material during firing tends to keep the temperature distribution of the piezoelectric material constant.

[0164] The lowest electrode 23F in the peripheral piezoelectric section 19BP may overlap the center of the corresponding pressure chamber 15 (for example, the individual actuator 17A in Figure 7).

[0165] In this case, for example, compared to a configuration in which the electrode 23F has an opening in the center of the pressure chamber 15 (for example, the individual actuator 17B in Figure 9), the probability of an electric field caused by the fluctuating potential at electrode 23E being applied to the ink is reduced. Also, since all electrodes 23 of the central piezoelectric section 19AC overlap in the center of the pressure chamber 15, the fact that electrode 23F overlaps in the center of the pressure chamber 15 makes it easier to balance the volume of the upper electrode and the volume of the lower electrode directly above the center of the pressure chamber 15. As a result, for example, the probability of unintended warping occurring in the individual actuator 17 directly above the center of the pressure chamber 15 is reduced.

[0166] The electrode 23E, which is one layer above the lowest electrode 23F in the peripheral piezoelectric portion 19BP, may be arranged so as not to overlap the center of the corresponding pressure chamber 15. The lowest electrode 23F may extend inward from the inner edge of electrode 23E and outward from the outer edge of electrode 23E in a planar perspective (for example, the individual actuator 17A in Figure 7 or the individual actuator 17B in Figure 9). That is, when the lead-out portion 23b is not considered, in a planar perspective, electrode 23E may be contained within electrode 23F.

[0167] In this case, for example, compared to the configuration where the magnitude relationship is not as described above (individual actuator 17G in Figure 15), the probability of an electric field caused by the fluctuating potential at electrode 23E being applied to the ink is reduced. Also, for example, if the ceramic green sheet on which electrode 23E is provided and the ceramic green sheet on which electrode 23F is provided are separate, even if there is an error in the alignment of the two ceramic green sheets, as long as electrode 23E is contained within electrode 23F in a planar view, the size of the overlapping region (active region) of electrodes 23E and 23F will not change. In other words, the accuracy of the dimensions of the active region is improved. However, from the viewpoint of improving the accuracy of the size of the active region, the opposite is also true; electrode 23F may be contained within electrode 23E.

[0168] In a planar view, the outer edge portion of the region where all electrodes 23 in the central piezoelectric section 19AC overlap and the inner edge portion of the region where all electrodes 23 in the peripheral piezoelectric section 19BP overlap may overlap with each other. Also, in a planar view, the outer edge portion of the region where all electrodes 23 in the peripheral piezoelectric section 19BP overlap may overlap with the outer region of the corresponding pressure chamber 15.

[0169] In this case, for example, compared to the configuration without overlap as described above (individual actuator 17G in Figure 15), it becomes easier to increase the central displacement of the individual actuator 17. Also, since electrodes 23C and 23D, which constitute the shared electrode 23Z, share the outer circumference portion of the former and the inner circumference portion of the latter, the need to place a conductor solely for connecting the two can be reduced, while improving the reliability of the connection between them. Furthermore, in a plan view, since there is no gap between the outer edge of electrode 23F and plate 35J, which has an opening that constitutes the upper part of the pressure chamber 15, the probability of an electric field caused by fluctuating potential being applied to the ink can be reduced.

[0170] The electrode 23 above the lowest electrode 23 in the central piezoelectric section 19AC (for example, electrode 23C in the individual actuator 17A in Figure 7) (for example, electrode 23B) and the electrode above the lowest electrode 23F in the peripheral piezoelectric section 19BP (for example, electrode 23E) may be electrically connected.

[0171] In this case, compared to, for example, a configuration in which drive signals are input separately to electrodes 23B and 23E (which may also be included in the technology of this disclosure), it is possible to input drive signals to both electrodes 23B and 23E more easily. Consequently, the operation described with reference to Figure 5 can be easily realized. Furthermore, in a configuration in which electrodes 23B and 23E are not electrically connected, for example, the degree of freedom in the relative relationship of their drive timings is improved.

[0172] In each of the multiple individual actuators 17, the two or more electrodes 23 in the central piezoelectric section 19AC and the three or more electrodes 23 in the peripheral piezoelectric section 19BP may be electrically connected to each other: the shared electrode 23Z, all of the upper electrodes 23 every other from the shared electrode 23Z, and all of the lower electrodes 23 every other from the shared electrode 23Z. The remaining electrodes 23 do not have to be electrically connected to the shared electrode 23Z, and may be electrically connected to each other.

[0173] In this case, for example, the effect of being able to easily input drive signals to multiple electrodes 23 as described above, as well as the effect of easily applying ground potential to multiple electrodes 23, can be obtained.

[0174] The piezoelectric actuator 11 may have an insulating layer (piezoelectric layer 21E) located below the lowest electrode 23F.

[0175] In this case, for example, the probability of the electrode 23F coming into contact with the ink is reduced. As a result, for example, the probability of the electrode 23F material deteriorating is reduced. Also, for example, since the insulating layer is not the piezoelectric layer 21 to which an electric field is applied for driving, the electric field for driving can be moved upward away from the ink. As a result, for example, the probability of an electric field being applied to the ink can be reduced.

[0176] Each of the two or more piezoelectric layers 21 in the peripheral piezoelectric portion 19BP may be thinner than each of the one or more piezoelectric layers 21 in the central piezoelectric portion 19AC (for example, the individual actuator 17A in Figure 7).

[0177] In this case, assuming that, for example, the number of layers and total thickness of the piezoelectric layers 21 in the piezoelectric actuator 11, and the voltage applied to each piezoelectric layer 21 of the peripheral piezoelectric portion 19BP are the same as in the above embodiment and in other embodiments (for example, the individual actuator 17C in Figure 11), the strength of the electric field applied to the piezoelectric layers 21 of the peripheral piezoelectric portion 19BP can be increased. As a result, the amount of deformation of the peripheral piezoelectric portion 19BP can be increased, and consequently, the central displacement of the individual actuator 17 can be increased. Also, for example, compared to the case where all piezoelectric layers 21 are thin, it becomes easier to secure the volume of the electrode 23 on the lower side of the piezoelectric actuator 11. As a result, when forming the piezoelectric actuator 11 by firing, it becomes easier to bend the piezoelectric actuator 11 so that it is convex upward.

[0178] One or more piezoelectric layers 21 in the central piezoelectric section 19AC may overlap the inner peripheral portion of the corresponding pressure chamber 15 and have an unpolarized portion (an inactive region of the peripheral non-driven section 19AP). Two or more piezoelectric layers 21 in the peripheral piezoelectric section 19BP may overlap the center of the corresponding pressure chamber 15 and have an unpolarized portion (an inactive region of the central non-driven section 19BC).

[0179] In this case, for example, the likelihood of unintended deformation occurring due to leaked electric fields is reduced. Also, for example, the need to perform polarization treatment on the inactive region is reduced, thus reducing the need to provide electrodes solely for polarization treatment, and simplifying the configuration.

[0180] The technology relating to this disclosure is not limited to the embodiments described above and may be implemented in various forms.

[0181] The recording device may be a plotter. The recording device may be a handheld printer, which is held and moved by the user and moves relative to the recording medium (a transport device is not required). The recording device may move the head relative to the recording medium by moving the head with a robot or the like (a transport device may transport the head).

[0182] The recording medium is not limited to paper. For example, the recording medium may be cloth, wood, tile, printed circuit board (more specifically, an insulating layer on which a conductive pattern is printed), or a vehicle body.

[0183] The liquid dispensing device may be used for purposes other than recording. For example, the liquid dispensing device may be used in the preparation of chemicals. Specifically, for example, the liquid dispensing device may dispense a predetermined amount of liquid chemical agent or a liquid containing a chemical agent toward a reaction vessel or the like.

[0184] As can be seen from the examples of recording media above, the liquid is not limited to ink. For example, it may be paint or a conductive material printed on a printed circuit board.

[0185] The liquid dispensing device may be composed entirely or partially of MEMS (Micro Electro Mechanical Systems). For example, the flow channel member does not have to be made of plates with holes formed in them, laminated with adhesive.

[0186] 1...Printer (recording device), 3...Head (liquid ejection device), 7...Flow channel member, 7b...Pressure surface, 11...Piezoelectric actuator, 15...Pressure chamber, 17...Individual actuator, 21...Piezoelectric layer, 23...Electrode, 23C...Electrode (lowest layer, first electrode), 23D...Electrode (uppermost layer, second electrode), 23F...Electrode (lowest layer, second electrode), 23Z...Combined electrode, 19AC...Central piezoelectric section, 19BP...Peripheral piezoelectric section.

Claims

1. A flow channel member having a pressurizing surface and a plurality of pressure chambers arranged along the pressurizing surface; a piezoelectric actuator overlapping the pressurizing surface; the piezoelectric actuator having a plurality of individual actuators that pressurize each of the plurality of pressure chambers; each of the plurality of individual actuators being composed of one or more first piezoelectric layers and two or more first electrodes alternately overlapping on the side facing the pressurizing surface, the two or more first electrodes being a central piezoelectric portion overlapping in the center of the corresponding pressure chamber; and the piezoelectric actuator being composed of two or more second piezoelectric layers and three or more second electrodes alternately overlapping on the side facing the pressurizing surface, the three or more second electrodes being a peripheral piezoelectric portion overlapping on the inner peripheral edge of the corresponding pressure chamber; in the piezoelectric actuator, when the side facing the pressurizing surface is referred to as the lower layer side and the side opposite to the pressurizing surface is referred to as the upper layer side, the lowest first electrode and the uppermost second electrode are located in the same layer and are connected to each other to form a shared electrode; the shared electrodes of the plurality of individual actuators are electrically connected to each other. A liquid dispensing device in which the number of the two or more second piezoelectric layers is even, and the bottommost second electrode is electrically connected to the multi-purpose electrode.

2. The liquid dispensing device according to claim 1, wherein the second electrodes of the lowest layer of the plurality of individual actuators are connected to each other by linear wiring within the same layer.

3. In each of the plurality of individual actuators, the two or more first electrodes and the three or more second electrodes consist of the shared electrode, a plurality of third electrodes that are not electrically connected to the same electrode of another individual actuator, and the remaining one or more fourth electrodes, and each of the one or more fourth electrodes is connected to the same electrode of another individual actuator by linear wiring in the same layer, the liquid dispensing device according to claim 1 or 2.

4. The liquid dispensing device according to any one of claims 1 to 3, wherein the multi-purpose electrodes of the multiple individual actuators are spread out in a planar manner and connected to one another.

5. The liquid dispensing device according to any one of claims 1 to 4, wherein the lowest second electrode is superimposed on the center of the corresponding pressure chamber.

6. The liquid dispensing device according to any one of claims 1 to 5, wherein the second electrode one layer above the lowest second electrode does not overlap the center of the corresponding pressure chamber, and the lowest second electrode, in a plan view, extends inward beyond the inner edge of the second electrode one layer above and outward beyond the outer edge of the second electrode one layer above.

7. In a planar view, the outer edge portion of the region where all first electrodes overlap and the inner edge portion of the region where all second electrodes overlap overlap, and in a planar view, the outer edge portion of the region where all second electrodes overlap and the outer region of the corresponding pressure chamber overlap. This is the liquid dispensing device according to any one of claims 1 to 6.

8. The liquid dispensing device according to any one of claims 1 to 7, wherein the first electrode one layer above the lowest first electrode and the second electrode one layer above the lowest second electrode are electrically connected.

9. A liquid dispensing device according to any one of claims 1 to 8, wherein in each of the plurality of individual actuators, the two or more first electrodes and the three or more second electrodes, the combined electrode, all of the first electrodes located in alternating layers above the combined electrode, and all of the second electrodes located in alternating layers below the combined electrode are electrically connected to each other, and the remaining electrodes are not electrically connected to the combined electrode, but are electrically connected to each other.

10. The liquid dispensing device according to any one of claims 1 to 9, wherein the piezoelectric actuator has an insulating layer located below the second electrode of the lowest layer.

11. The liquid dispensing device according to any one of claims 1 to 10, wherein each of the two or more second piezoelectric layers is thinner than each of the one or more first piezoelectric layers.

12. The liquid dispensing device according to any one of claims 1 to 11, wherein the one or more first piezoelectric layers overlap the inner peripheral edge of the corresponding pressure chamber and have an unpolarized portion, and the two or more second piezoelectric layers overlap the center of the corresponding pressure chamber and have an unpolarized portion.

13. A recording device comprising: a liquid dispensing device according to any one of claims 1 to 12; and a transport device for moving the liquid dispensing device and a recording medium relative to each other.

14. A piezoelectric actuator having a plurality of individual actuators that deform when a voltage is applied, wherein each of the plurality of individual actuators has a central piezoelectric section composed of one or more first piezoelectric layers and two or more first electrodes that are alternately overlapped toward the first side, and a peripheral piezoelectric section composed of two or more second piezoelectric layers and three or more second electrodes that are alternately overlapped toward the first side, and located around the central piezoelectric section when viewed through a plane, wherein in the piezoelectric actuator, when the first side is referred to as the lower layer side and the side opposite to the first side as the upper layer side, the lowest first electrode and the uppermost second electrode are located on the same layer and are connected to each other to form a shared electrode, the shared electrodes of the plurality of individual actuators are electrically connected to each other, the number of the two or more second piezoelectric layers is even, and the lowest second electrode is electrically connected to the shared electrode.

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