Liquid ejection head and liquid ejection apparatus

Abstract

To provide a desirable arrangement and constitution when a detection part for detecting residual vibration, a pressure part for discharging liquid, and an absorption chamber for absorbing pressure fluctuation are separately provided.SOLUTION: The liquid discharge head includes a nozzle, a pressure chamber that applies pressure for discharging liquid from the nozzle by driving a first piezoelectric element, a detection chamber that detects residual vibration of the pressure applied in the pressure chamber by a second piezoelectric element, an absorption chamber that absorbs vibration of the pressure applied in the pressure chamber by a third piezoelectric element, and a wiring substrate that electrically couples the pressure chamber, the detection chamber, the absorption chamber, and the outside of the liquid discharge head. The first piezoelectric element of the liquid discharge head is electrically connected to the wiring substrate, the second piezoelectric element is electrically connected to the wiring substrate, and the third piezoelectric element, the first piezoelectric element, the wiring substrate, and the second piezoelectric element are arranged in this order when viewed from the up-down direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a liquid ejection head and a liquid ejection apparatus. [Background technology]

[0002] Liquid ejection heads and liquid ejection devices such as printers that use such heads are known, which use actuators such as piezoelectric elements to apply pressure to liquid such as ink in a pressure chamber and eject the liquid from a nozzle. As shown in Patent Document 1, attempts have been made to detect residual vibrations that occur in the liquid in the pressure chamber after ejection, thereby determining whether the nozzle is clogged with foreign matter or whether the liquid has thickened. Regarding the residual vibrations that occur in the liquid in the pressure chamber, as shown in Patent Document 2, studies have also been made to provide a vibration absorbing unit that uses piezoelectric elements to absorb the vibrations of the liquid, driving the actuator at a predetermined throughput to prevent vibrations from occurring during a previous drive from affecting the next drive when continuously ejecting liquid. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-147363 [Patent Document 2] Japanese Patent Publication No. 2022-13678 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology of Patent Document 1 is excellent in that it uses the same piezoelectric element and the same pressure chamber to drive the liquid ejection and detect residual vibrations. However, because the piezoelectric element and pressure chamber are used for both drive and detection, there is a problem that when attempting to detect residual vibrations in real time while ejecting ink, the drive frequency for ejection is limited, and sufficient throughput may not be achieved. For this reason, the inventors considered a configuration in which a detection chamber and piezoelectric element for detecting residual vibrations are provided separately from the pressure chamber and piezoelectric element for ejecting the liquid, and an absorption chamber is also provided to absorb vibrations generated in the liquid. However, sufficient consideration has not been given to the appropriate placement of the pressure chamber, detection chamber, absorption chamber, etc., or the wiring method for the piezoelectric elements used in each part. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms or application examples. One form of the present disclosure is a liquid ejection head. The liquid ejection head includes a nozzle, a first piezoelectric element, a second piezoelectric element, a third piezoelectric element, a pressure chamber that applies pressure to eject liquid from the nozzle when the first piezoelectric element is driven, a detection chamber that detects residual vibration of the pressure applied in the pressure chamber using the second piezoelectric element, an absorption chamber that absorbs vibration of the pressure applied in the pressure chamber using the third piezoelectric element, and a wiring board that electrically connects the liquid ejection head to the outside. In the liquid ejection head, the first piezoelectric element is electrically connected to the wiring board, and the second piezoelectric element is electrically connected to the wiring board, and the third piezoelectric element, the first piezoelectric element, the wiring board, and the second piezoelectric element are arranged in this order when viewed from above. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is an exploded perspective view showing a liquid ejection head according to a first embodiment. [Figure 2] FIG. 2 is an explanatory diagram showing a cross section of the liquid ejection head taken along line II-II in FIG. 1, together with other members that constitute the liquid ejection device. [Figure 3] FIG. 3 is a plan view showing a portion of the communication plate according to the first embodiment. [Figure 4] FIG. 2 is a plan view showing a part of a pressure chamber substrate according to the first embodiment. [Figure 5] FIG. 3 is an explanatory diagram showing a schematic configuration of a vibration absorbing section and a pressure applying section. [Figure 6] FIG. 4 is an explanatory diagram showing an enlarged view of a lead-out wiring portion of the pressure unit. [Figure 7] FIG. 2 is an explanatory diagram showing a schematic configuration of a vibration detection unit. [Figure 8] FIG. 3 is an explanatory diagram schematically showing, for comparison, the configurations of the first to third piezoelectric elements of the first embodiment. [Figure 9] 9 is an explanatory diagram showing cross sections of the parts in FIG. 8 . [Figure 10] 6 is a graph showing an example of a drive signal applied to a first piezoelectric element and a detection signal corresponding to residual vibrations generated in ink by the drive signal. [Figure 11] FIG. 4 is an explanatory diagram showing an example of wiring from a flexible wiring board to each piezoelectric element. [Figure 12] FIG. 10 is an explanatory diagram showing a comparative example of wiring from a flexible wiring board to each piezoelectric element. [Figure 13] FIG. 10 is an explanatory diagram showing the configuration of a liquid ejection head according to a second embodiment. [Figure 14] 10A and 10B are explanatory diagrams showing a comparison between the form of a piezoelectric element in a pressure unit and the form of a piezoelectric element in a vibration detection unit of the third embodiment. [Figure 15] FIG. 10 is an explanatory diagram for explaining a modified example of the third embodiment. [Figure 16] 10A and 10B are explanatory diagrams showing a comparison between the form of a piezoelectric element in a pressure unit and the form of a piezoelectric element in a vibration detection unit of the fourth embodiment. [Figure 17] FIG. 1 is an explanatory diagram showing an example of a liquid ejection device. DETAILED DESCRIPTION OF THE INVENTION

[0007] A. First embodiment: (A1) Overall configuration of liquid ejection head: The overall configuration of a liquid ejection head 10 according to a first embodiment will be described with reference to FIGS. 1 to 11. The dimensions and scale of each part in each drawing are for ease of understanding and may differ from the actual dimensions. The embodiments described below are preferred specific examples of the present disclosure, and therefore various technically preferable limitations are applied. However, the scope of the present disclosure is not limited to these embodiments unless otherwise specified in the following description. Furthermore, in this specification, "ejection" refers to the delivery of liquid from a nozzle or the like to the outside. Ejection includes various modes in which a predetermined amount of liquid is output to the outside, such as spraying, squirting, spraying, discharging, and intermittent ejection, regardless of the type of liquid, output time, number of times, etc.

[0008] FIG. 1 is an exploded perspective view of a liquid ejection head 10, and FIG. 2 is a cross-sectional view taken along the XZ plane including line II-II shown in FIG. 1, passing through one nozzle N. In this embodiment, the liquid ejection head 10 is configured as an ink ejection head in a printer. Ink is introduced into the liquid ejection head 10, and a portion of the ink is ejected from the nozzle N toward the outside, for example, toward a printing medium. Because the ink is circulated, ink not ejected from the nozzle N is discharged from the liquid ejection head 10. For this reason, the terms "supply side" and "discharge side" are sometimes used in this specification. The "supply side" refers to the upstream side of a pressure chamber CC, which will be described later, in terms of the liquid flow path. Also, the term "supply side" may refer to the upstream side of the pressure chamber CC. The "discharge side" refers to the downstream side of the pressure chamber CC in terms of the liquid flow path. Note that the "discharge side" does not include the nozzle N, which will be described later. Also, the term "discharge side" may refer to the downstream side of the pressure chamber CC. Note that the liquid is not limited to ink; the liquid ejection head 10 can be configured to eject other liquids.

[0009] In the following description, the three intersecting directions may be referred to as the X-axis direction, the Y-axis direction, and the Z-axis direction. The X-axis direction includes the X1 direction and the X2 direction, which are opposite directions. The Y-axis direction includes the Y1 direction and the Y2 direction, which are opposite directions. As illustrated in FIG. 1 , the Y-axis direction is the arrangement direction of multiple nozzles N in the liquid ejection head. The Z-axis direction includes the Z1 direction and the Z2 direction, which are opposite directions. The Z1 direction is the direction in which liquid is ejected from the nozzles N. In this embodiment, it is the direction along the direction of gravity, and the downward direction according to gravity coincides with the Z1 direction. In this case, the Z2 direction may be referred to as the "upper side" or "upward direction," and the Z1 direction may be referred to as the "lower side" or "downward direction." The X-axis direction is a direction perpendicular to both the Y-axis direction and the Z-axis direction. Note that in this embodiment, the Z-axis direction coincides with the up-down direction according to the direction of gravity, but it does not necessarily have to coincide with the direction of gravity and may be set at a predetermined angle with respect to the direction of gravity.

[0010] First, the configuration of the liquid ejection head 10, in which multiple substrates are stacked, will be described with reference to the drawings. As shown in Figures 1 and 2, the liquid ejection head 10 includes, in order from the bottom in the Z1 direction along the Z axis, a nozzle substrate 21, a communication plate 24, a pressure chamber substrate 25, a sealing plate 27, and a case 28. The thickness directions of the nozzle substrate 21, the communication plate 24, the pressure chamber substrate 25, the sealing plate 27, and the case 28 are aligned with the Z axis direction. Sealed spaces S1 to S3 are formed in the sealing plate 27, spaced apart in the X axis direction. Sealed spaces S1 and S2 house multiple first and second piezoelectric elements 51 and 72, respectively, and sealed space S3 houses a single third piezoelectric element 73. The structures of the first to third piezoelectric elements 51, 72, 73 will be explained in detail later, but the first piezoelectric element 51 includes a first diaphragm 26 provided integrally at a position where it seals the sealed space S1, the second piezoelectric element 72 includes a second diaphragm 29 provided integrally at a position where it seals the sealed space S2, and the third piezoelectric element 73 includes a third diaphragm 23 provided integrally at a position where it seals the sealed space S3. Note that the third diaphragm 23 may be called a compliance substrate, focusing on its vibration absorption function.

[0011] The liquid ejection head 10 also includes a wiring substrate 60. In this embodiment, the wiring substrate 60 is configured using a COF (Chip on Film). In this embodiment, as will be described later, the wiring substrate 60 has a control circuit 62 chip mounted on a flexible wiring substrate 61 on a film. However, the wiring substrate 60 may be a simple wiring substrate without the control circuit 62. The liquid ejection head 10 includes, from the supply side, a supply-side common liquid chamber RA, a vibration absorbing section 70A, a pressurizing section 70C, a wiring introduction section RC, a vibration detecting section 70B, and a discharge-side common liquid chamber RB, as shown in FIG. 2 , by stacking substrates such as the nozzle substrate 21. In the vibration absorbing section 70A, a third vibration plate 23 is sandwiched between a sealing plate 27 and a pressure chamber substrate 25. In the pressurizing section 70C, a first vibration plate 26 is sandwiched between the sealing plate 27 and a pressure chamber substrate 25, and in the vibration detecting section 70B, a second vibration plate 29 is sandwiched between the sealing plate 27 and a pressure chamber substrate 25.

[0012] A sealing plate 27 is disposed in the Z2 direction from the first diaphragm 26 and the third diaphragm 23. The sealing plate 27 includes a portion that is outer than the third diaphragm 23 in the X-axis direction. The outer portion of the sealing plate 27 in the X-axis direction is located in the Z2 direction from the pressure chamber substrate 25. The sealing plate 27 covers the third diaphragm 23, the first diaphragm 26, the second diaphragm 29, the plurality of first piezoelectric elements 51, and the pressure chamber substrate 25. A case 28 is disposed on the sealing plate 27. The first piezoelectric elements 51 are provided corresponding to the pressure chambers CC. Note that although the third diaphragm 23, the first diaphragm 26, and the second diaphragm 29 are depicted as a single continuous plate in FIGS. 1 and 2, the plate thicknesses of these members may differ, as will be described in the third and fourth embodiments.

[0013] Next, the structures of the sealing plate 27 and the case 28 will be described. The sealing plate 27 has a rectangular shape when viewed in the Z-axis direction. The sealing plate 27 protects the multiple first piezoelectric elements 51, the multiple second piezoelectric elements 72, and the single third piezoelectric element 73, and also reinforces the mechanical strength of the pressure chamber substrate 25, the first diaphragm 26, the second diaphragm 29, and the third diaphragm 23. The sealing plate 27 is adhered to the first diaphragm 26, etc., by, for example, an adhesive. The sealing plate 27 is fixed to the pressure chamber substrate 25 via the first diaphragm 26, the second diaphragm 29, and the third diaphragm 23.

[0014] The sealing plate 27 has sealed spaces S1 to S3 formed therein. A recess is formed in the lower surface of the sealing plate 27. The spaces formed by this recess are the sealed spaces S1 to S3. The sealed spaces S1 to S3 are formed so as to be continuous with each other in the Y-axis direction. The sealed space S1 is formed so as to overlap with a plurality of pressure chambers CC when viewed in the Z-axis direction. The sealed space S1 houses a plurality of first piezoelectric elements 51. The sealed space S2 is formed so as to overlap with a plurality of detection chambers (hereinafter referred to as vibration detection chambers) DB for detecting vibrations of the liquid when viewed in the Z-axis direction. The sealed space S2 houses a plurality of second piezoelectric elements 72. The sealed space S3 is formed so as to overlap with an absorption chamber DA that functions as a damper for absorbing vibrations of the liquid when viewed in the Z-axis direction. In this embodiment, the sealed space S3 houses one third piezoelectric element 73.

[0015] The sealing plate 27 is further formed with a flow path 44A included in the common liquid chamber RA and a flow path 44B included in the common liquid chamber RB. The flow paths 44A and 44B are formed to penetrate the sealing plate 27 in the Z-axis direction. The flow path 44A is located in the X1 direction of the sealed space S3. The flow path 44B is located in the X2 direction of the sealed space S2.

[0016] The case 28 is located in the Z2 direction of the sealing plate 27. A supply port 42A, a discharge port 42B, and flow paths 43A and 43B are formed in the case 28. The flow path 43A is included in the common liquid chamber RA. The flow path 43A is formed so as to overlap with the flow path 44A of the sealing plate 27 when viewed in the Z-axis direction. The supply port 42A communicates with the flow path 43A. The flow path 43B is included in the common liquid chamber RB. The flow path 43B is formed so as to overlap with the flow path 44B of the sealing plate 27 when viewed in the Z-axis direction. The discharge port 42B communicates with the flow path 43B.

[0017] Compliance substrates 77A and 77B are fixed to the case 28. As shown in FIG. 2, the compliance substrates 77A and 77B are provided in the common liquid chambers RA and RB. The compliance substrates 77A and 77B are different from the third diaphragm 23 provided in correspondence with the absorption chamber DA. Note that, although FIG. 2 shows a configuration in which the compliance substrates 77A and 77B are not exposed to the outside of the liquid ejection head 10, the compliance substrates 77A and 77B may be exposed to the outside of the liquid ejection head 10.

[0018] The compliance substrate 77A is provided corresponding to the flow path 43A of the common liquid chamber RA. The compliance substrate 77A is located in the X1 direction of the flow path 43A. The compliance substrate 77A is arranged so as to cover the opening that forms the flow path 43A. The thickness direction of the compliance substrate 77A is along the X-axis direction. The compliance substrate 77A extends in the Y-axis direction.

[0019] The compliance substrate 77B is provided corresponding to the flow path 43B of the common liquid chamber RB. The compliance substrate 77B is located in the X2 direction of the flow path 43B. The compliance substrate 77B is arranged so as to cover the opening that forms the flow path 43B. The thickness direction of the compliance substrate 77B is along the X-axis direction. The compliance substrate 77B extends in the Y-axis direction.

[0020] Compliance substrates 77A and 77B are preferably made of a material that is more flexible than third diaphragm 23, but may have the same configuration as third diaphragm 23. Compliance substrates 77A and 77B include an elastic layer and an insulating layer. The elastic layer is made of, for example, silicon dioxide (SiO2). The insulating layer is made of, for example, zirconium dioxide (ZrO2).

[0021] The compliance substrate 77A is deformable in response to the pressure of ink in the flow path 43A of the common liquid chamber RA. The compliance substrate 77A deforms in response to the pressure of ink, absorbing pressure fluctuations in the flow path 43A of the common liquid chamber RA. Similarly, the compliance substrate 77B is deformable in response to the pressure of ink in the flow path 43B of the common liquid chamber RB. The compliance substrate 77B is deformable in response to the pressure of ink, absorbing pressure fluctuations in the flow path 43B of the common liquid chamber RB.

[0022] (A2) Ink flow path: Next, the configuration of the flow channels 40 through which ink flows will be described. The flow channels 40 through which ink flows are formed in the liquid ejection head 10. The flow channels 40 include a supply port 42A, an outlet 42B, common liquid chambers RA and RB, an absorption chamber DA, a pressure chamber CC, a vibration detection chamber DB, communicating flow channels 47A to 47C, and a nozzle N. The flow channels 40 include a plurality of individual flow channels provided individually corresponding to the nozzles N, and a common flow channel provided in common to the individual flow channels. In order to understand the distinction between these, reference will be made as appropriate to FIG. 3, which is a plan view showing a portion of the communicating plate 24, and FIG. 4, which is a plan view showing a portion of the pressure chamber substrate 25.

[0023] The flow path 40 has a supply flow path 41A and a discharge flow path 41B. The supply flow path 41A is a flow path upstream of the pressure chamber CC and is a flow path within the communicating plate 24 and the pressure chamber substrate 25. The supply flow path 41A includes a flow path 45A, a flow path 46A, and an absorption chamber DA. The discharge flow path 41B is a flow path downstream of the pressure chamber CC and is a flow path within the communicating plate 24 and the pressure chamber substrate 25. The discharge flow path 41B includes a communicating flow path 47C, a communicating flow path 47B, a vibration detection chamber DB, a flow path 46B, and a flow path 45B. Note that the supply flow path 41A does not include the flow path 44A in the sealing plate 27 or the flow path 43A in the case 28. The discharge flow path 41B does not include the flow path 44B in the sealing plate 27 or the flow path 43B in the case 28.

[0024] The common liquid chamber RA is provided in common to multiple pressure chambers CC and functions as a supply reservoir. The common liquid chamber RA is continuous in the Y-axis direction. The common liquid chamber RA includes a flow path 43A provided in the case 28, a flow path 44A provided in the sealing plate 27, a flow path 45A provided in the pressure chamber substrate 25, and a flow path 46A provided in the communication plate 24. These flow paths 43A, 44A, 45A, and 46A are continuous in the Z-axis direction.

[0025] In the communicating plate 24, a communicating flow path 47A continuing from the supply flow path 41A is disposed downstream of the common liquid chamber RA, and is connected to the common liquid chamber RA via a flow path 46A. As shown in FIG. 3, the communicating flow path 47A is a common flow path commonly connected to the flow path 46A. The communicating flow path 47A is a common flow path commonly connected to multiple pressure chambers CC. In this embodiment, the communicating flow path 47A is provided in common to multiple pressure chambers CC, but it may have other shapes, such as individual flow paths corresponding to the pressure chambers CC, or a common flow path shared by several pressure chambers CC, as long as it can absorb pressure fluctuations upstream of the pressure chambers CC.

[0026] The absorption chamber DA is provided corresponding to the vibration absorbing unit 70A. The absorption chamber DA is located in the Z2 direction of the communication flow path 47A and communicates with the pressure chamber CC downstream of the communication flow path 47A. The absorption chamber DA is located in the X1 direction when viewed from the pressure chamber CC. A nozzle N communicates with each of the multiple pressure chambers CC. The nozzle N is an opening that penetrates the communication plate 24 and the nozzle substrate 21 at the same position toward the Z1 direction of the pressure chamber CC. The position of the nozzle N in the X axis direction is approximately the center of the pressurizing unit 70C.

[0027] A plurality of nozzles N are formed in the nozzle substrate 21. The plurality of nozzles N form a nozzle row N1. The nozzle row N1 includes a plurality of nozzles N lined up in the Y-axis direction. The nozzles N are through-holes that penetrate the nozzle substrate 21 in the Z-axis direction.

[0028] As shown in Figures 3 and 4, the multiple communication channels 47C are provided for the multiple pressure chambers CC, respectively. In other words, the communication channels 47C are individual channels that individually connect to the multiple pressure chambers CC. The multiple communication channels 47C communicate with the downstream of the pressure chambers CC. As shown in Figure 2, the downstream end of the pressure chamber CC, that is, the end in the X2 direction, and the upstream end of the communication channel 47C, that is, the end in the X1 direction, overlap when viewed in the Z-axis direction. A communication channel 47B is disposed downstream of each of the multiple communication channels 47C. The ends of the multiple communication channels 47C opposite the pressure chamber CC are directly connected to the communication channel 47B.

[0029] The vibration detection chambers DB are provided corresponding to the pressure chambers CC, respectively. The vibration detection chambers DB are located in the Z2 direction of the communication flow path 47B. The vibration detection chambers DB are respectively connected to the communication flow paths 47B. The vibration detection chambers DB are connected to the pressure chambers CC via the communication flow paths 47B and 47C. The vibration detection chambers DB are provided to detect residual vibrations that occur in the liquid when the liquid is ejected from the nozzle N by pressurizing the liquid in the pressurizing unit 70C using the pressurizing unit 70C.

[0030] The common liquid chamber RB is provided downstream of the pressure chambers CC and is shared by the pressure chambers CC via the communication flow paths 47C and 47B. The common liquid chamber RB is commonly connected to the communication flow paths 47B and functions as a discharge reservoir. The common liquid chamber RB is connected to the pressure chambers CC via the communication flow paths 47B and 47C. The common liquid chamber RB is located downstream of

[0031] The common liquid chamber RB is continuous in the Y-axis direction. The common liquid chamber RB includes a flow path 43B provided in the case 28, a flow path 44B provided in the sealing plate 27, a flow path 45B provided in the pressure chamber substrate 25, and a flow path 46B provided in the communication plate 24. These flow paths 43B, 44B, 45B, and 46B are continuous in the Z-axis direction.

[0032] In this embodiment, as described above, the liquid ejection head 10 employs a circulation system in which ink that has flowed through the pressure chambers CC is circulated. A circulation mechanism 18 that circulates the ink is connected to the liquid ejection head 10. The circulation mechanism 18 includes a pump, and supplies ink from a liquid container to the liquid ejection head 10 by pump operation. The ink passes through a supply port 42A of the liquid ejection head 10 and is supplied to a common liquid chamber RA. Furthermore, ink discharged from the liquid ejection head 10 is collected from the common liquid chamber RB through a discharge port 42B.

[0033] The ink in the liquid container 2 is transported by a pump or the like (not shown), flows through the supply flow path 81, passes through the supply port 42A shown in FIG. 2, and flows into the common liquid chamber RA. The ink in the common liquid chamber RA passes through the communication flow path 47A and the absorption chamber DA and is supplied to the pressure chamber CC. A portion of the ink in the pressure chamber CC is ejected from the nozzle N.

[0034] Ink that is not ejected from the nozzle N passes through the communication flow path 47C and the communication flow path 47B and flows into the common liquid chamber RB. A portion of the ink that flows through the communication flow path 47C flows into the vibration detection chamber DB. The ink in the common liquid chamber RB flows into the recovery flow path 82 through the outlet 42B and is recovered by the circulation mechanism 18. In the liquid ejection head 10 of this embodiment, the ink is circulated in this manner.

[0035] As shown in FIGS. 2 and 3, the communication plate 24 is formed with flow paths 46A, 47A, 47C, and 47B, which are part of the common liquid chamber RA, and a flow path 46B, which is part of the common liquid chamber RB. That is, the communication plate 24 is provided with a supply flow path and a part of a discharge flow path. The communication plate 24 is formed with through-holes, grooves, recesses, or the like. These through-holes, grooves, recesses, or the like form part of the common liquid chambers RA and RB and the communicating flow paths 47A, 47B, and 47C. In the illustrated embodiment, the absorption chambers DA and the communicating flow paths 47A are common flow paths corresponding to the pressure chambers CC, but at least one of them can also be formed as an individual flow path. Furthermore, if a common flow path is used, a configuration is also possible in which the absorption chambers DA and the communicating flow paths 47A are provided as common flow paths corresponding to multiple pressure chambers CC. The size (volume) of the vibrating region of the vibration absorbing unit 70A changes depending on whether the absorption chamber DA and the communicating flow path 47A are configured as individual flow paths or a common flow path. Therefore, the configuration of the absorption chamber DA and the communicating flow path 47A, i.e., whether they are individual flow paths or a common flow path, can be set according to the absorption efficiency required for the liquid ejection head 10. When at least some of the flow paths are configured as individual flow paths, the third piezoelectric element 73 of the vibration absorbing unit 70A may also be provided individually corresponding to the individual flow paths.

[0036] 2 and 4, the pressure chamber substrate 25 is formed with a flow path 45A which is part of the common liquid chamber RA, one absorption chamber DA, multiple pressure chambers CC, multiple vibration detection chambers DB, and a flow path 45B which is part of the common liquid chamber RA. In FIG. 4, the arrangement of the nozzles N is indicated by dashed lines to clarify the positional relationship between the nozzles N and the pressure chambers CC. The pressure chamber substrate 25 can be manufactured from a silicon single crystal substrate, for example. The pressure chamber substrate 25 may also be manufactured from other materials.

[0037] As shown in FIG. 4, the absorption chamber DA extends in the X-axis direction, and the absorption chamber DA and the common liquid chamber RA are spaced apart from each other in the X-axis direction. The absorption chamber DA and the pressure chamber CC are formed as a common space that is continuous in the X-axis direction. The absorption chamber DA penetrates the pressure chamber substrate 25 in the Z-axis direction. The absorption chamber DA has a predetermined volume. The absorption chamber DA is shaped to be continuous in the Y-axis direction. A relay flow path may be formed between the absorption chamber DA and the pressure chamber CC.

[0038] The pressure chambers CC extend in the X-axis direction. The pressure chambers CC penetrate the pressure chamber substrate 25 in the Z-axis direction. The pressure chambers CC have a predetermined volume. The multiple pressure chambers CC are arranged at predetermined intervals in the Y-axis direction. The multiple pressure chambers CC are connected to a common absorption chamber DA in the Y-axis direction. The multiple pressure chambers CC form a pressure chamber array CL aligned in the Y-axis direction. The pressure chamber array CL includes multiple pressure chambers CC. In Figure 4, imaginary lines L1 and L2 indicating the boundaries of the pressure chambers CC are shown by two-dot chain lines. The imaginary line L1 indicates the end of the pressure chamber CC in the X1 direction. The imaginary line L2 indicates the end of the pressure chamber CC in the X2 direction.

[0039] The multiple vibration detection chambers DB extend in the X-axis direction. The vibration detection chambers DB and the pressure chambers CC are spaced apart in the X-axis direction. As shown in FIG. 2, a communication flow path 47C is formed between the vibration detection chambers DB and the pressure chambers CC. The vibration detection chambers DB and the common liquid chamber RB are spaced apart from each other in the X-axis direction. When viewed in the Z-axis direction, the vibration detection chambers DB are formed to overlap with the communication flow path 47B. The vibration detection chambers DB penetrate the pressure chamber substrate 25 in the Z-axis direction. The vibration detection chambers DB and the communication flow path 47B are in communication with each other in the Z-axis direction. The vibration detection chambers DB have a predetermined volume. The multiple vibration detection chambers DB are arranged at predetermined intervals in the Y-axis direction.

[0040] As described above, the liquid ejection head 10 comprises, in order from the upstream side of the ink supply, the vibration absorbing unit 70A, the pressure applying unit 70C, and the vibration detecting unit 70B, and a wiring introduction portion RC is provided between the pressure applying unit 70C and the vibration detecting unit 70B. As shown in Fig. 1, this wiring introduction portion RC is formed from the opening 27a of the sealing plate 27 that continues to the opening of the case 28, and the wiring board 60 is introduced here. The wiring board 60 and the wiring from the wiring board 60 will be described later.

[0041] (A3) Configuration and Function of Vibration Absorbing Unit 70A, Pressurizing Unit 70C, and Vibration Detecting Unit 70B: Next, the configurations of the vibration absorbing unit 70A, the pressure applying unit 70C, and the vibration detecting unit 70B will be described with reference to FIGS. 5 to 7, focusing on the piezoelectric elements of each unit. FIG. 6 is an enlarged cross-sectional view of a portion of the first vibration plate 26, the first piezoelectric element 51, and the first wiring unit 54 in the pressure applying unit 70C shown in FIG. 5. As shown in FIGS. 5 to 7, the first piezoelectric element 51, the second piezoelectric element 72, and the third piezoelectric element 73 each have electrodes on the top surface (the end surface in the Z2 direction) and the bottom surface (the end surface in the Z1 direction) of the piezoelectric body. The piezoelectric body sandwiched between the two electrodes deforms due to the electrostrictive effect when a voltage is applied between the upper and lower electrodes. On the other hand, when an external force is applied to deform the piezoelectric body, a voltage is generated between the electrodes due to the piezoelectric effect. In this embodiment, the first piezoelectric element 51, second piezoelectric element 72, and third piezoelectric element 73 have roughly the same configuration, but the first piezoelectric element 51 is used as a piezoelectric element that generates vibrations in the first diaphragm 26 by applying a voltage between the electrodes, and the second piezoelectric element 72 is used as a piezoelectric element that generates pressure when vibrations are applied from outside to the second diaphragm 29, thereby detecting the vibrations. The third piezoelectric element 73 has the same configuration as the other piezoelectric elements, but the upper and lower electrodes are not electrically connected, and it is used as a mass for absorbing pressure changes in the liquid in the absorption chamber DA.

[0042] The first piezoelectric element 51, the second piezoelectric element 72, and the third piezoelectric element 73 have the same configuration, so the general configuration will be described first using the first piezoelectric element 51 as an example. The first piezoelectric element 51 has a first lower electrode 51a, a first upper electrode 51b, and a first piezoelectric body 51c, and further has a first vibration plate 26 below the first lower electrode 51a in the Z1 direction. The first lower electrode 51a, the first piezoelectric body 51c, and the first upper electrode 51b are layered in this order on the first vibration plate 26. The first piezoelectric body 51c is sandwiched between the first lower electrode 51a and the first upper electrode 51b. Here, the first lower electrode 51a is an individual electrode that applies a potential to the plurality of first piezoelectric elements 51 individually, and the first upper electrode 51b is a common electrode that applies a potential to the plurality of first piezoelectric elements 51 in common, but the first lower electrode 51a may be a common electrode and the first upper electrode 51b may be an individual electrode. This also applies to the second piezoelectric element 72 and the third piezoelectric element 73, which will be described later in order.

[0043] The first diaphragm 26 includes a first elastic layer 26a and a first insulating layer 26b. The first elastic layer 26a is made of, for example, silicon dioxide (SiO2). The first insulating layer 26b is made of, for example, zirconium dioxide (ZrO2).

[0044] A plurality of first piezoelectric elements 51 are formed on the first vibration plate 26 provided below the first lower electrode 51a in the Z1 direction. The first piezoelectric elements 51 are arranged at positions overlapping with the pressure chambers CC when viewed in the Z-axis direction. The first piezoelectric elements 51 are provided for each of the plurality of pressure chambers CC.

[0045] The first diaphragm 26 is driven by the first piezoelectric element 51 and vibrates in the Z-axis direction. The first diaphragm 26, which forms the upper wall surface of the pressure chamber CC, is driven by the first piezoelectric element 51 above the pressure chamber CC. The specific configuration, material, and thickness of the first diaphragm 26, as well as differences from the second diaphragm 29, will be described in detail later. However, for example, the total thickness of the first diaphragm 26 is, for example, 2 μm or less. The total thickness of the first diaphragm 26 may be 15 μm or less, 40 μm or less, or 100 μm or less. For example, if the total thickness of the first diaphragm 26 is 15 μm or less, it may include a resin layer. The first diaphragm 26 may be made of metal. Examples of metal include stainless steel and nickel. If the first diaphragm 26 is made of metal, the thickness of the first diaphragm 26 may be 15 μm or more and 100 μm or less.

[0046] The configuration of the first piezoelectric element 51 will be described in detail below. The first lower electrode 51a provided on the lower surface of the first piezoelectric element 51 in the Z1 direction is elongated along the X-axis direction. The multiple first lower electrodes 51a are arranged at intervals from each other in the Y-axis direction. The multiple first lower electrodes 51a are arranged for each of the multiple pressure chambers CC. The first lower electrodes 51a are respectively arranged at positions overlapping with the multiple pressure chambers CC when viewed in the Z-axis direction. The first upper electrode 51b provided on the upper surface of the first piezoelectric element 51 in the Z2 direction is strip-shaped and extends in the Y-axis direction. The first upper electrode 51b is continuous so as to cover the multiple first lower electrodes 51a.

[0047] The first lower electrode 51a includes an underlayer and an electrode layer. The underlayer includes, for example, titanium (Ti). The electrode layer includes, for example, a low-resistance conductive material such as platinum (Pt) or iridium (Ir). The electrode layer may be formed of an oxide such as strontium ruthenate (SrRuO) or lanthanum nickelate (LaNiO). The first piezoelectric element 51c is formed of a known piezoelectric material such as lead zirconate titanate (Pb(Zr,Ti)O) or ceramic.

[0048] The first upper electrode 51b includes a base layer and an electrode layer. The base layer includes, for example, titanium. The electrode layer includes, for example, a low-resistance conductive material such as platinum or iridium. The electrode layer may be formed of an oxide such as strontium ruthenate or lanthanum nickelate. Of the first piezoelectric body 51c, the region between the first lower electrode 51a and the first upper electrode 51b serves as a driving region. Driving regions are formed on each of the multiple pressure chambers CC.

[0049] A predetermined reference voltage is applied to the first upper electrode 51b. The reference voltage is a constant voltage, and is set to, for example, a voltage higher than the ground voltage. For example, a holding signal having a constant voltage is applied to the first upper electrode 51b. A drive signal having a fluctuating voltage is applied to the first lower electrode 51a. A voltage corresponding to the difference between the reference voltage applied to the first upper electrode 51b and the drive signal supplied to the first lower electrode 51a is applied to the first piezoelectric element 51c. The drive signal corresponds to the amount of liquid ejected from the nozzle N.

[0050] When a voltage is applied between the first lower electrode 51a and the first upper electrode 51b, the first piezoelectric body 51c is deformed, and the first piezoelectric element 51 generates energy that flexes and deforms the first diaphragm 26. The energy generated by the first piezoelectric element 51 causes the first diaphragm 26 to vibrate, changing the pressure of the liquid in the pressure chamber CC, and the liquid in the pressure chamber CC is ejected from the nozzle N.

[0051] As shown in FIG. 6, which is an enlarged view of the lead-out wiring portion, which is the connection portion between the pressure applying portion 70C and the first wiring portion 54, the first wiring portion 54 is connected to the Y-direction end portion of the first piezoelectric element 51. The first wiring portion 54 has an electrode layer 54a, a first adhesion layer 54b, and a first wiring layer 54c. The electrode layer 54a covers the X2-direction end face of the first piezoelectric body 51c. The X2-direction end face forms a plane intersecting with the X-axis direction. The first adhesion layer 54b covers the electrode layer 54a and the first lower electrode 51a. The first adhesion layer 54b is in close contact with the electrode layer 54a and the first lower electrode 51a. The first wiring layer 54c covers the first adhesion layer 54b. The first wiring layer 54c is electrically connected to the first lower electrode 51a via the first adhesion layer 54b.

[0052] The first piezoelectric element 51 is provided with a VBS wiring 55. The VBS wiring 55 is disposed on the first upper electrode 51b and extends in the Y-axis direction. The VBS wiring is strip-shaped when viewed from the Z-axis direction and is formed to cover the first upper electrode 51b. The VBS wiring 55 connects the first upper electrode 51b of the first piezoelectric element 51 to the flexible wiring substrate 61. The VBS wiring 55 is electrically connected to the wiring substrate 60 at the end of the liquid ejection head 10 in the Y-axis direction. The VBS wiring 55 is provided as an auxiliary wiring that substantially reduces the electrical resistance of the first upper electrode 51.

[0053] An insulating adhesive layer 59 made of an insulating adhesive is formed between the first piezoelectric element 51 and the sealing plate 27. The insulating adhesive layer 59 bonds the first piezoelectric element 51 to the sealing plate 27 and also insulates the end face of the first wiring layer 54c from the end face of the VBS wiring 55. The latter prevents electrical conduction that may occur due to ion migration.

[0054] The first wiring portions 54 of the liquid ejection head 10 are connected to the first lower electrodes 51a, respectively. The first wiring portions 54 extend in the X-axis direction and are drawn out into the openings 27a of the wiring introduction portions RC. The openings 27a penetrate the sealing plate 27 in the Z-axis direction. The first wiring portions 54 are electrically connected to the wiring substrate 60 at positions corresponding to the openings 27a when viewed in the Z-axis direction. The first wiring portions 54 are formed of a conductive material having a lower resistance than the first lower electrodes 51a. For example, the first wiring portions 54 are a conductive pattern having a structure in which a conductive film of gold (Au) is laminated on the surface of a conductive film made of nichrome (NiCr).

[0055] Next, the vibration absorbing section 70A will be briefly described. The supply-side vibration absorbing section 70A is provided for the supply-side absorption chamber DA. As shown in FIG. 5, the vibration absorbing section 70A includes a third piezoelectric element 73. The third piezoelectric element 73 includes a third diaphragm 23. The third diaphragm 23 is located in the X1 direction of the first diaphragm 26. The third diaphragm 23 is disposed on the upper surface of the pressure chamber substrate 25. The third diaphragm 23 covers the portion of the opening of the pressure chamber substrate 25 that corresponds to the absorption chamber DA. The third diaphragm 23 forms the upper wall surface of the absorption chamber DA. The third diaphragm 23 is disposed at a position that corresponds to the sealed space S3 formed in the sealing plate 27 when viewed in the Z-axis direction.

[0056] The third diaphragm 23 includes a flexible film. The third diaphragm 23 includes a third elastic layer 23a and a third insulating layer 23b. The third elastic layer 23a is made of, for example, silicon dioxide (SiO2). The third insulating layer 23b is made of, for example, zirconium dioxide (ZrO2). The third elastic layer 23a is formed on the pressure chamber substrate 25, and the third insulating layer 23b is formed on the third elastic layer 23a. The third elastic layer 23a is formed continuously with the first elastic layer 26a of the first diaphragm 26 that covers the pressure chamber CC. The third insulating layer 23b is formed continuously with the first insulating layer 26b of the first diaphragm 26. The third diaphragm 23 is deformable when subjected to ink pressure. The third diaphragm 23 deforms due to ink pressure and absorbs pressure fluctuations of the ink in the absorption chambers DA. The multiple third diaphragms 23 move individually in correspondence with the absorption chambers DA.

[0057] As shown in FIG. 5, the vibration absorbing unit 70A includes a third piezoelectric element 73. The third piezoelectric element 73 is disposed at a position overlapping the absorption chamber DA when viewed in the Z-axis direction. Similar to the first piezoelectric element 51, the third piezoelectric element 73 includes a third lower electrode 73a, a third upper electrode 73b, a third piezoelectric body 73c, and a third diaphragm 23. The third lower electrode 73a, the third upper electrode 73b, and the third piezoelectric body 73c are layered in this order on the third diaphragm 23. The third piezoelectric body 73c is sandwiched between the third lower electrode 73a and the third upper electrode 73b. The electrode arrangement, structure, and materials are similar to those of the first piezoelectric element 51, and therefore detailed description thereof will be omitted.

[0058] Finally, the configuration of the vibration detection unit 70B will be described using FIG. 7. As shown in the figure, the vibration detection unit 70B includes a second piezoelectric element 72. The second piezoelectric element 72 includes a second diaphragm 29. The second diaphragm 29 is located in the X2 direction of the first diaphragm 26. The second diaphragm 29 is located on the opposite side of the first diaphragm 26 from the third diaphragm 23 in the X-axis direction. As shown in the figure, the second diaphragm 29 is disposed on the upper surface of the pressure chamber substrate 25. The second diaphragm 29 covers the portion of the opening of the pressure chamber substrate 25 that corresponds to the vibration detection chamber DB. The second diaphragm 29 forms the upper wall surface of the vibration detection chamber DB. The second diaphragm 29 is disposed at a position corresponding to the sealed space S2 formed in the sealing plate 27 when viewed in the Z-axis direction.

[0059] The second diaphragm 29 includes a flexible film. The second diaphragm 29 includes a second elastic layer 29a and a second insulating layer 29b. The second elastic layer 29a is made of, for example, silicon dioxide (SiO2). The second insulating layer 29b is made of, for example, zirconium dioxide (ZrO2). The second elastic layer 29a is formed on the pressure chamber substrate 25, and the second insulating layer 29b is formed on the second elastic layer 29a. The second elastic layer 29a may be formed continuously with the first elastic layer 26a of the first diaphragm 26, or may be formed separately. The second insulating layer 29b may be formed continuously with the first insulating layer 26b of the first diaphragm 26, or may be formed separately.

[0060] The multiple second vibration plates 29 are provided corresponding to the multiple vibration detection chambers DB aligned in the Y-axis direction. The second vibration plates 29 are deformable when subjected to ink pressure. The second vibration plates 29 deform in response to fluctuations in ink pressure within the vibration detection chambers DB. The multiple second vibration plates 29 move individually in correspondence with the multiple vibration detection chambers DB. A multiple number of second piezoelectric elements 72 are formed on the second vibration plate 29. The second piezoelectric elements 72 are arranged at positions overlapping the vibration detection chambers DB when viewed in the Z-axis direction. The second piezoelectric elements 72 are provided corresponding to the multiple vibration detection chambers DB respectively.

[0061] Similar to the first piezoelectric element 51, the second piezoelectric element 72 has a second lower electrode 72a, a second upper electrode 72b, a second piezoelectric body 72c, and a second vibration plate 29. The second lower electrode 72a, the second upper electrode 72b, and the second piezoelectric body 72c are layered in this order on the second vibration plate 29. The second piezoelectric body 72c is sandwiched between the second lower electrode 72a and the second upper electrode 72b. The second lower electrode 72a is elongated along the X-axis direction. The multiple second lower electrodes 72a are arranged at intervals in the Y-axis direction. The multiple second lower electrodes 72a are arranged for each of the multiple vibration detection chambers DB. The second lower electrodes 72a are arranged at positions overlapping the multiple vibration detection chambers DB when viewed in the Z-axis direction. The second upper electrode 72b is strip-shaped and extends in the Y-axis direction. The second upper electrode 72b is continuous and covers the plurality of second lower electrodes 72a.

[0062] The structure and material of the second lower electrode 72a are the same as those of the first lower electrode 51a of the first piezoelectric element 51. The structure and material of the second upper electrode 72b are the same as those of the first upper electrode 51b of the first piezoelectric element 51. The structure and material of the second piezoelectric body 72c are the same as those of the first piezoelectric body 51c of the first piezoelectric element 51. The second piezoelectric element 72 can be formed in the same manner as the first piezoelectric element 51 and the third piezoelectric element 73. Although not shown in detail, the second lower electrode 72a and the second upper electrode 72b of the second piezoelectric element 72 are connected to the flexible wiring substrate 61, similar to the first lower electrode 51a and the first upper electrode 51b of the first piezoelectric element 51. In the drawing, the wiring from the flexible wiring substrate 61 to the second piezoelectric element 72 is shown as a second wiring portion 74. The configuration of the connection portion between the second piezoelectric element 72 and the second wiring portion 74 is similar to the configuration using the electrode layer 54a, first adhesion layer 54b, and first wiring layer 54c of the first wiring portion 54 in the first piezoelectric element 51 shown in Figure 6, so illustration and description of these are omitted.

[0063] Next, the configurations of the first piezoelectric element 51, the second piezoelectric element 72, and the third piezoelectric element 73 will be compared and explained using FIGS. 8 and 9. FIG. 8 is an explanatory diagram schematically showing the configurations of the first to third piezoelectric elements of the first embodiment, and FIG. 9 is an explanatory diagram showing cross sections of the respective parts in FIG. 8. FIG. 8 schematically shows the shapes of the cross sections of the first to third piezoelectric elements in the XZ plane as viewed in the Y direction, and FIG. 9 schematically shows cross sections of the first to third piezoelectric elements as viewed in the JJ, KK, and LL arrows in FIG. 8. For convenience of illustration, the first diaphragm 26, the second diaphragm 29, and the third diaphragm 23 are separately labeled as the first piezoelectric element 51, the second piezoelectric element 72, and the third piezoelectric element 73, but as already explained, the first diaphragm 26 is included in the first piezoelectric element 51, the second diaphragm 29 is included in the second piezoelectric element 72, and the third diaphragm 23 is included in the third piezoelectric element 73. In the illustrations of other embodiments, the two may also be given separate reference numerals for convenience of illustration.

[0064] As shown by comparing the first piezoelectric element 51, the second piezoelectric element 72, and the third piezoelectric element 73 of the first embodiment, the first piezoelectric element 51, the second piezoelectric element 72, and the third piezoelectric element 73 of the present embodiment have substantially the same thicknesses and materials for the respective lower electrodes, piezoelectric bodies, and upper electrodes, and differ only in length in the X direction. Furthermore, the thicknesses and materials of the first to third elastic layers 26a, 29a, and 23a and the first to third insulating layers 26b, 29b, and 23b in the respective diaphragms 26, 29, and 23 of each piezoelectric element are also the same.

[0065] As shown in FIG. 9, at least the first piezoelectric element 51 and the second piezoelectric element 72 have substantially the same cross-sectional shape in the YZ plane. In this embodiment, the third piezoelectric element 73 has a shape that is continuous in the Y direction, and this is the difference in shape. In the third piezoelectric element 73, the absorption chambers DA are continuous in the Y direction, and this configuration is adopted for the purpose of efficiently absorbing pressure fluctuations of the ink on the supply side. The third piezoelectric element 73 may also be configured by arranging multiple piezoelectric elements, each with a shape similar to the first piezoelectric element 51 and the second piezoelectric element 72, in the Y direction. Note that in FIG. 9, for convenience of illustration, the hatching indicating the cross section of the piezoelectric bodies of each piezoelectric element, i.e., the first piezoelectric body 51c, the second piezoelectric body 72c, and the third piezoelectric body 73c, has been omitted.

[0066] In this way, the first piezoelectric element 51, the second piezoelectric element 72, and the third piezoelectric element 73 are positioned at approximately the same thickness, i.e., the thickness and material of each part stacked in the Z direction, so the Z direction position (also called the first height) of the neutral axis of the first piezoelectric element 51 of the pressure applying section 70C, the Z direction position (also called the second height) of the neutral axis of the second piezoelectric element 72 of the vibration detecting section 70B, and the Z direction position (also called the second height) of the neutral axis of the third piezoelectric element 73 of the vibration absorbing section 70A are approximately the same.

[0067] The neutral axis of a piezoelectric element refers to the position within a cross section where tensile and compressive forces are balanced when a piezoelectric body deforms and a bending moment is generated in the component. The position where tensile and compressive forces symmetrically generated by the deformation of the piezoelectric body are balanced is, so to speak, the fulcrum of the deformation, and the force generated by the deformation is applied to one side of the fulcrum (the point of force), and acts on the other side of the fulcrum (the point of action). In this way, the structure and characteristics of each piezoelectric element, including the height of the neutral axis, are approximately identical, which increases the productivity of the piezoelectric elements and reduces costs. Furthermore, because the characteristics are consistent, the design and handling of each part is easier.

[0068] A drive signal output to the first piezoelectric element 51 of the pressure applying unit 70C and a detection signal detected by the second piezoelectric element 72 of the vibration detecting unit 70B are exchanged with the control circuit 62 via a flexible wiring board 61. The flexible wiring board 61 is a flexible wiring board. The flexible wiring board 61 is, for example, an FPC. The flexible wiring board 61 may also be, for example, an FFC. FPC is an abbreviation for Flexible Printed Circuit. FFC is an abbreviation for Flexible Flat Cable.

[0069] 6, the flexible wiring board 61 is electrically connected to the first lower electrode 51a and the first upper electrode 51b of the first piezoelectric element 51 of the pressure applying unit 70C and the second lower electrode 72a and the second upper electrode 72b of the vibration detecting unit 70B via the first wiring part 54 described below. The flexible wiring board 61 is electrically connected to the control part 20 shown in FIG. 2, and exchanges signals, such as signals for driving the first piezoelectric element 51 of the pressure applying unit 70C and detection signals corresponding to residual vibrations generated in the second piezoelectric element 72 of the vibration detecting unit 70B, with the control part 20 via the control circuit 62.

[0070] The control circuit 62 is mounted on the flexible wiring board 61. The control circuit 62 includes a switching element for driving the first piezoelectric element 51. The control circuit 62 receives a drive signal Com for the first piezoelectric element 51 output from the control unit 20. The switching element of the control circuit 62 switches whether or not to supply the drive signal Com to the first piezoelectric element 51. The control circuit 62 supplies a drive voltage or current to the first piezoelectric element 51 to vibrate the first diaphragm 26. The control circuit 62 also receives a voltage signal generated in the second piezoelectric element 72 due to vibration of the second diaphragm 29 caused by residual vibration in the ink, extracts information such as the magnitude and frequency of the residual vibration, and outputs the information to the control unit 20.

[0071] FIG. 10 shows an example of the drive signal applied between the electrodes of the first piezoelectric element 51 of the pressure applying unit 70C in the above embodiment, and the residual vibrations that occur in the ink when ink is ejected in response to the drive signal. When ink is to be ejected from nozzle N, as shown in the upper part of the figure, a first drive signal VinA is applied between the electrodes of the first piezoelectric element 51 of the ejection unit 70C. The first drive signal VinA is a signal with a waveform change that drives the meniscus of nozzle N in a pull-push-pull manner. The first piezoelectric element 51 is driven by the first drive signal VinA, which causes a pressure change in the pressure chamber CC, causing an ink droplet to be ejected from the nozzle N. The pull-push-pull drive generates pressure fluctuations in the ink in the pressure chamber CC. These pressure fluctuations remain for a certain period of time even after the ink droplet is ejected. This is called residual vibration.

[0072] The vibration detection unit 70B detects this pressure fluctuation by the second piezoelectric element 72. The pressure fluctuation generated in the pressure chamber CC propagates to the vibration detection chamber DB, where it is detected by the second piezoelectric element 72 and output as a residual vibration signal Vout. Specifically, the second piezoelectric element 72 detects the ink pressure change during the period Td from the point at which the drive signal VinA returns to the predetermined potential V3 as residual vibration, and outputs the residual vibration signal Vout. From the residual vibration signal VoutA, the control circuit 62 obtains the period NTc, phase time TF, and amplitude Vmax of the residual vibration. Furthermore, the control unit 20, which obtains this information from the control circuit 62, detects events such as nozzle clogging and increased ink viscosity.

[0073] The wiring from the flexible wiring board 61 to the first piezoelectric element 51 and the second piezoelectric element 72 is shown schematically in FIG. 11. In the figure, the flexible wiring board 61 does not represent a single wire but a collection of multiple wires. A drive signal output from the control circuit 62 to the first piezoelectric element 51 via the flexible wiring board 61 is transmitted to the first upper electrode 51b and the first lower electrode 51a via the first wiring section 54. A detection signal from the second piezoelectric element 72 is transmitted to the second upper electrode 72b and the second lower electrode 72a via the second wiring section 74 to the second piezoelectric element 72.

[0074] The first wiring portion 54 and the second wiring portion 74 are formed by a method such as vapor deposition on the upper surfaces of the first diaphragm 26 and the second diaphragm 29, respectively. Alternatively, a thin metal film may be formed on the surface of the first diaphragm 26 or the second diaphragm 29 and then etched. In either case, the first wiring portion 54 and the second wiring portion 74, which are used to energize the upper and lower electrodes of the first piezoelectric element 51 and the second piezoelectric element 72, are not arranged overlapping each other when viewed in the Z-axis direction, but are arranged offset from each other in the Y-direction. Furthermore, no wiring is provided to the third lower electrode 73a and the third upper electrode 73b of the third piezoelectric element 73.

[0075] (A4) Effects of the first embodiment: In the liquid ejection head 10 of the first embodiment described above, the pressurizing unit 70C for ejecting liquid ink and the vibration detecting unit 70B for detecting residual vibrations generated by ink ejection are separately provided, and residual vibrations of the ink on the supply side of the pressurizing unit 70C can be absorbed by the vibration absorbing unit 70A. Therefore, residual vibrations can be detected without reducing the throughput of ink droplets ejected from the nozzles N by the pressurizing unit 70C, and ejection performance abnormalities such as nozzle clogging and thickening, as well as deviation trends, can be detected. Furthermore, the pressure fluctuations absorbed by the absorption chamber DA and the third piezoelectric element 73 of the vibration absorbing unit 70A are fluctuations in supply pressure on the ink supply side. Since the vibration detecting unit 70B is provided downstream (on the discharge side) of the pressure chamber CC, residual vibrations are not absorbed by the vibration absorbing unit 70A. Therefore, the vibration detecting unit 70B can accurately detect residual vibrations generated in the pressure chamber CC of the pressurizing unit 70C. This is because, when viewed in the Z-axis direction, i.e., from the top to bottom, the third piezoelectric element 73 of the vibration absorbing section 70A, the first piezoelectric element 51 of the pressure applying section 70C, the flexible wiring board 61 of the wiring board 60 arranged in the wiring introduction section RC, and the second piezoelectric element 72 of the vibration detecting section 70B are arranged in this order when viewed from the liquid supply side.

[0076] Compared to a configuration in which, from the ink supply side, the first piezoelectric element 51 for ejection in the pressure applying section 70C, the third piezoelectric element 73 for absorption in the vibration absorbing section 70A, and the second piezoelectric element 72 for detection in the vibration detecting section 70B are arranged, most of the residual vibrations are not absorbed in the absorption chamber DA before reaching the detection chamber DB, and the vibrations reach sufficiently all the way to the vibration detection chamber DB of the vibration detecting section 70B, thereby achieving high accuracy in residual vibration detection. Alternatively, when the first piezoelectric element 51 for ejection of the pressure applying section 70C, the second piezoelectric element 72 for vibration detection of the vibration detecting section 70B, and the third piezoelectric element 70 for absorption of the vibration absorbing section 70A are arranged in this order from the ink supply side, that is, compared to a configuration in which the vibration absorbing section 70A is located furthest downstream, i.e., on the discharge side, and the vibration detecting section 70B is located immediately downstream of the pressure applying section 70C, the vibration detection chamber DB is not affected by the large vibrations that may occur when continuous ejection is performed by the first piezoelectric element 51 of the pressure applying section 70C, and sufficient accuracy can be obtained in detecting clogging of the nozzle N or thickening of the ink near the nozzle N in residual vibration detection.

[0077] In this embodiment, a wiring lead-in portion RC is provided between the pressure applying portion 70C including the first piezoelectric element 51 and the vibration detecting portion 70B including the second piezoelectric element 72, and the wiring substrate 60 is introduced therein. Therefore, as shown in FIG. 11 , the wiring extending from the flexible wiring substrate 61 of the wiring substrate 60, i.e., the first wiring portion 54 ensuring electrical conduction to the first piezoelectric element 51 and the second wiring portion 74 ensuring electrical conduction to the second piezoelectric element 72, can be arranged to extend on both sides of the flexible wiring substrate 61. The liquid ejection head 10 can be easily connected to an external device, in this case, the control unit 20, by leading the wiring substrate 60 from above the liquid ejection head 10 into the wiring lead-in portion RC and extending it in the X direction. The first piezoelectric element 51 can be driven by wiring the control unit 20 from the pressure applying portion 70C to the first piezoelectric element 51 via the flexible wiring substrate 61 and the first wiring portion 54. Furthermore, by wiring the second piezoelectric element 72 of the vibration detection unit 70B to the control unit 20 via the flexible wiring board 61, a signal corresponding to the electromotive force generated in the second piezoelectric element 72 by residual vibration can be transmitted to the outside of the liquid ejection head 10. Since some of the exchange of both signals is consolidated on the common flexible wiring board 61, costs can be reduced.

[0078] In this embodiment, the first wiring portion 54 and the second wiring portion 74 are laid on opposite sides of the flexible wiring substrate 61, which reduces crosstalk between the two wiring portions, and in particular, it is unlikely that a voltage pulse (see FIG. 10) that drives the first piezoelectric element 51 will cause noise from the second piezoelectric element 72 to be carried on the second wiring portion 74, reducing the accuracy of detecting residual vibration. For comparison, FIG. 12 shows an example of the state of the wiring portion when the wiring lead-in portion RC is provided between the vibration absorbing portion 70A and the pressure applying portion 70C. In this example, the flexible wiring substrate 61r is disposed between the third piezoelectric element 73 and the first piezoelectric element 51. Therefore, the first wiring portion 54r, which electrically connects the flexible wiring substrate 61r to the first lower electrode 51a and the first upper electrode 51b of the first piezoelectric element 51, and the second wiring portion 74r, which electrically connects the flexible wiring substrate 61r to the second lower electrode 72a and the second upper electrode 72b of the second piezoelectric element 72, are routed approximately parallel to each other within the range XT. Therefore, in this range XT, so-called crosstalk is likely to occur due to stray capacitance between the wirings. In particular, the current flowing due to the drive signal for driving the first piezoelectric element 51 is large, potentially generating noise large enough to reduce the accuracy of the residual vibration detection signal from the second piezoelectric element 72. The wiring of this embodiment shown in FIG. 11 is less likely to cause such crosstalk, ensuring sufficient accuracy of the residual vibration detection signal from the second piezoelectric element 72.

[0079] In the first embodiment, the third piezoelectric element 73 of the vibration absorbing unit 70A, the first piezoelectric element 51 of the pressure applying unit 70C, the wiring substrate 60 of the wiring lead-in portion RC, and the second piezoelectric element 72 of the vibration detecting unit 70B are arranged in this order from the ink supply side. However, from the perspective of reducing crosstalk, the arrangement of the vibration absorbing unit 70A and the vibration detecting unit 70B may be reversed. In the first embodiment, the third piezoelectric element 73 is used as a weight for absorbing pressure fluctuations and does not have a wiring portion connecting it to the flexible wiring substrate 61. However, if a voltage is applied to the third piezoelectric element 73 for vibration absorption, wiring portions may be provided from the flexible wiring substrate 61 to the third lower electrode 73a and the third upper electrode 73b of the third piezoelectric element 73. In this case, the third piezoelectric element 73 does not need to function as a sensor for detecting residual vibrations like the second piezoelectric element 72, or require the necessary detection accuracy. Therefore, the third piezoelectric element 73 may be located on the same side of the flexible wiring substrate 61 as the first piezoelectric element 51. Therefore, there is no need to detour the wiring to the third piezoelectric element 73, and each wiring can be efficiently arranged in a narrow space. Also, since the third piezoelectric element 73 can be arranged close to the first piezoelectric element 51, pressure fluctuations of the ink can be efficiently absorbed.

[0080] In this embodiment, the distance between the pressure chamber CC and the absorption chamber DA is smaller than the distance between the pressure chamber CC and the vibration detection chamber DB. Therefore, a wiring lead-in portion RC is provided between the pressure chamber CC and the vibration detection chamber DB, allowing the wiring substrate 60 to be easily introduced. The width of the pressure chamber CC in the extension direction is larger than the width of the vibration detection chamber DB in the extension direction, and is also larger than the width of the absorption chamber DA in the extension direction. In other words, the width of the pressure chamber CC in the X direction of the liquid ejection head 10 is set to a length sufficient to ensure ejection performance, while the widths of the vibration detection chamber DB and the absorption chamber DA are made small. This prioritizes ink ejection performance and allows the size of the liquid ejection head 10 in the X direction to be compact. Since the functions of not only the pressure chamber CC but also the vibration detection chamber DB and the absorption chamber DA are improved by increasing their widths, the widths of these chambers may be increased within the limits of the size of the liquid ejection head 10.

[0081] Furthermore, in this embodiment, the width of the vibration detection chamber DB in the extension direction is larger than the width of the absorption chamber DA in the extension direction. This makes it possible to ensure sufficient detection accuracy of residual vibration in the vibration detection unit 70B. In particular, when the distance between the vibration detection chamber DB and the pressure chamber CC is large, the residual vibration is attenuated accordingly, so it is desirable to ensure the width of the vibration detection chamber DB in the X direction so that the attenuated vibration can be detected with a predetermined accuracy. Furthermore, the area of ​​the absorption chamber DA, which contributes to the ability to absorb pressure fluctuations, can be ensured by the width of the absorption chamber DA in the nozzle arrangement direction (Y direction). Therefore, pressure fluctuations can be sufficiently absorbed even if the width of the absorption chamber DA in the X direction is not particularly large.

[0082] B. Second embodiment: Next, the configuration of a liquid ejection head 10B according to a second embodiment will be described. FIG. 13 is an explanatory diagram showing the configuration of the liquid ejection head 10B according to the second embodiment. As shown in the figure, the ink flow direction, i.e., the ink supply side and ink discharge side, of this liquid ejection head 10B are reversed compared to the liquid ejection head 10 of the first embodiment. Specifically, ink circulated by the circulation mechanism 18 is supplied from the supply flow path 81 to the supply port 42A and then supplied to the liquid ejection head 10B via the common liquid chamber RB, which includes the flow paths 43B, 44B, and 45B. The common liquid chamber RB functions as a supply reservoir. The supplied ink passes through the supply flow path 41A, the communication flow path 47B, the vibration detection chamber DB, the pressure chamber CC, the absorption chamber DA, the communication flow path 47A, and the discharge flow path 41B, and then reaches the common liquid chamber RA. The common liquid chamber RA functions as a discharge reservoir. The ink further passes through the flow path 45A, the flow path 44A, and the flow path 43A included in the common liquid chamber RA, is discharged from the discharge port 42B, and circulates through the recovery flow path 82 to the circulation mechanism 18. The other configurations are the same as those in the first embodiment.

[0083] In the liquid ejection head 10B of the second embodiment, the vibration detection unit 70B is located closer to the ink supply side than the pressure application unit 70C. Therefore, the second piezoelectric element 72 of the vibration detection unit 70B can detect not only residual vibration but also pressure fluctuations on the supply side. If the pressure fluctuations on the supply side are within a predetermined range, the liquid ejection device 11 ejects ink using the first piezoelectric element 51. The resulting residual vibrations are detected by the second piezoelectric element 72, allowing for detection of clogged nozzles N and increased ink viscosity, as in the first embodiment. Furthermore, if the pressure fluctuations on the ink supply side are detected to be greater than a predetermined magnitude, a pump malfunction in the circulation mechanism 18 can be detected, and ink ejection using the first piezoelectric element 51 can be interrupted. Also, as shown in FIG. 13 , in the second embodiment, the wiring introduction portion RC is located between the pressure application unit 70C and the vibration detection unit 70B, which, as described above, reduces crosstalk between the wiring portions. Thus, the second embodiment also achieves the other advantages of the first embodiment.

[0084] C. Third embodiment: (C1) An embodiment in which the neutral axis on the vibration detection unit side is higher than that on the pressure unit side: In the first and second embodiments described above, as shown in FIGS. 8 and 9, the thickness of the third piezoelectric element 73 including the third vibration plate 23 of the vibration absorbing unit 70A, the thickness of the first piezoelectric element 51 including the first vibration plate 26 of the pressure applying unit 70C, and the thickness of the second piezoelectric element 72 including the second vibration plate 29 of the vibration detecting unit 70B are all the same. Therefore, the position (height) of the neutral axis of each piezoelectric element is approximately the same. The thickness of each part may be different depending on the characteristics required of each piezoelectric element. Note that the overall configuration of the liquid ejection head 10 in the third embodiment is the same as that of the first and second embodiments, and therefore illustrations and descriptions other than the differences will be omitted.

[0085] In the liquid ejection head 10 of the third embodiment, the positions (heights) of the neutral axes of the first piezoelectric element 51 and the second piezoelectric element 72 are different. FIG. 14 is an explanatory diagram comparing the shapes of the first piezoelectric element 511 in the pressure unit 70C2 and the second piezoelectric element 721 in the vibration detection unit 70B2 in the third embodiment. The upper part of the diagram schematically shows the cross-sections of both elements in the XZ plane as viewed in the Y direction, and the lower part of the diagram schematically shows the cross-sections taken along the arrows JJ and KK of the upper diagram. In some of the diagrams, for convenience of illustration, the first vibration plate 261 and the second vibration plate 291 are labeled separately from the first piezoelectric element 511 and the second piezoelectric element 721. However, as shown in the lower part of the diagram, the first vibration plate 261 is included in the first piezoelectric element 511, and the second vibration plate 291 is included in the second piezoelectric element 721. In the explanation of the modified examples to be given later, for convenience of illustration, the two may be separately designated by reference numerals.

[0086] As shown in the figure comparing the first piezoelectric element 511 and the second piezoelectric element 721 of the third embodiment, comparing the first vibration plate 261 of the first piezoelectric element 511 of the pressure applying unit 70C2 with the second vibration plate 291 of the second piezoelectric element 721 of the vibration detecting unit 70B2, the thickness K1 of the first insulating layer 261b constituting the first vibration plate 261 is smaller than the thickness J1 of the second insulating layer 291b constituting the second vibration plate 291. The first piezoelectric element 511 and the second piezoelectric element 721 have substantially the same dimensions in at least the X direction, except for the thicknesses of the first insulating layers 261b and 291b. As a result, the Z-direction position (also referred to as the first height) of the neutral axis of the first piezoelectric element 511 of the pressure applying unit 70C2 is different from the Z-direction position (also referred to as the second height) of the neutral axis of the second piezoelectric element 721 of the pressure applying unit 70B2.

[0087] The neutral axis of a piezoelectric element refers to the position in a cross section where tensile and compressive forces balance when the piezoelectric body deforms and a bending moment is generated in the component. The position where tensile and compressive forces symmetrically generated by the deformation of the piezoelectric body balance is, so to speak, the fulcrum of the deformation. The force generated by the deformation is applied to one side of the fulcrum (point of force) and acts on the other side of the fulcrum (point of action). In the case of the pressure applying unit 70C2, the first piezoelectric element 511 is attached to approximately the center of the first diaphragm 261 in the X direction. The first piezoelectric body 511c and first insulating layer 261b of the attached first piezoelectric element 511 have tensile stress, and the first elastic layer 261a has compressive stress. The position where the compressive stress and tensile stress balance corresponds to the position of the neutral axis NA. As shown in the figure, when the thickness J1 of the second insulating layer 291b is greater than the thickness K1 of the first insulating layer 261b, the position (height) of the neutral axis NA of the second piezoelectric element 721 is higher in the Z direction than the position (height) of the neutral axis NA of the first piezoelectric element 511.

[0088] When a predetermined voltage is applied between the first lower electrode 511a and the first upper electrode 511b of the first piezoelectric element 511, the first piezoelectric body 511c is deformed. At this time, the point of application of stress due to the deformation of the first piezoelectric body 511c and the point of application of stress that deforms the first elastic layer 261a of the first diaphragm 261 are on opposite sides of the neutral axis NA as the fulcrum. According to the principle of leverage, the force applied to the point of application becomes a force according to the ratio of the distance from the point of application to the fulcrum (the position of the neutral axis) to the distance from the fulcrum to the point of application, and acts on the first elastic layer 261a at the point of application. Comparing the first piezoelectric element 511 and the second piezoelectric element 722, as shown in the figure, the position of the neutral axis NA is lower in the first piezoelectric element 511, which has a thinner first insulating layer 261b, and therefore, in the first piezoelectric element 511, the force generated in the first piezoelectric body 511c in response to the voltage applied between the electrodes is amplified and deforms the first diaphragm 261. As a result, a strong force acts on the ink filled in the pressure chamber CC, making it easier to ensure the pressure required for ejecting ink from the nozzle N in the pressure applying section 70C2.

[0089] In contrast, in the vibration detection unit 70B2, the second piezoelectric element 721 is provided to detect residual vibrations applied to the second diaphragm 291. In the second piezoelectric element 721, when residual vibrations in the ink are applied to the second diaphragm 291 and the second piezoelectric body 721c is deformed, an electromotive force is generated by the piezoelectric effect, which changes the potential of the second lower electrode 721a relative to the second upper electrode 721b. By detecting this change in potential with a voltage detector or the like, it is possible to detect the force applied to the second diaphragm 29, i.e., the magnitude of the residual vibrations. In the vibration detection unit 70B2, the thickness J1 of the second insulating layer 291b of the second diaphragm 291 to which the second piezoelectric element 721 is attached is greater than the thickness K1 of the corresponding first insulating layer 261b of the pressure application unit 70C2. Therefore, as described above, the Z-direction position (second position) of the neutral axis NA is higher than the Z-direction position (first height) of the neutral axis NA of the first piezoelectric element 511 in the pressure applying portion 70C2.

[0090] As a result, in vibration detection unit 70B2, the positions of the point of force and the point of action are reversed compared to pressure application unit 70C2, so the force due to the deformation of second diaphragm 291 is intensified, as with pressure application unit 70C2, and acts at the point of action of second piezoelectric element 721. As shown in the figure, the position of neutral axis NA is higher in second piezoelectric element 721, which has thicker first insulating layer 291b, so the force applied to second diaphragm 291 by residual vibration is amplified, so to speak, and deforms second piezoelectric element 721. For this reason, the electromotive force generated by the piezoelectric effect can be increased, making it possible to easily and accurately detect residual vibration.

[0091] In the liquid ejection head 10 of the third embodiment described above, the first piezoelectric element 511 used in the vibration detection unit 70B2 and the second piezoelectric element 721 used in the pressure application unit 70C2 have substantially the same configuration, but the thickness J1 of the second insulating layer 291b of the second vibration plate 291 to which the second piezoelectric element 721 of the vibration detection unit 70B2 is bonded is greater than the thickness K1 of the first insulating layer 261b of the first vibration plate 261 to which the first piezoelectric element 511 of the pressure application unit 70C2 is bonded. This allows the position of the neutral axis NA of the vibration detection unit 70B2 to be higher in the Z direction than the position of the neutral axis NA of the pressure application unit 70C2, thereby satisfying the characteristics required of both the pressure application unit 70C2 and the vibration detection unit 70B2. Specifically, in the pressure application unit 70C2, the force exerted by the first piezoelectric element 511 on the outside in response to the applied voltage is strengthened, and this pressurizes the ink in the pressure chamber CC, thereby ensuring ink ejection from the nozzle N. Furthermore, the second piezoelectric element 721 in the vibration detection unit 70B2 is deformed by a force that is an intensified version of the force received from the residual vibration of the ink in the vibration detection chamber DB, so that the residual vibration can be accurately detected. Since the second piezoelectric element 721 used in the vibration detection unit 70B2 and the first piezoelectric element 511 used in the pressure unit 70C can be made to have substantially the same configuration, the liquid ejection head 10 can be easily manufactured. Furthermore, by doing so, the ink ejection throughput of the liquid ejection head 10 can be sufficiently increased.

[0092] Although the above description does not mention the thickness of the third diaphragm 23 in the vibration absorbing section 70A, or in other words, the thickness of the third insulating layer 23b, in this embodiment, the thickness of the third insulating layer 23b is the same as that of the adjacent first insulating layer 261b. Therefore, the third insulating layer 23b and the first insulating layer 261b can be manufactured integrally. The thickness of the third insulating layer 23b may be greater or smaller than the thickness K1 of the first insulating layer 261b or the thickness J1 of the first insulating layer 291b, or may be the same as either one, as long as the absorption characteristics are maintained.

[0093] (C2) Variation: In the above embodiment, the positions (heights) of the neutral axes NA of the two piezoelectric elements are made different by making the thicknesses of the first insulating layers 261b and 291b different, but they can also be made different by other methods. In Modification 1, as shown in the upper part of Fig. 15, the thickness of the second insulating layer 292b of the second piezoelectric element 722 and the thickness of the first diaphragm 262 of the first piezoelectric element 512 are made the same, and the heights of the neutral axes of the second piezoelectric body 722c and the first piezoelectric body 512c are made different.

[0094] The first piezoelectric element 512 includes a first lower electrode 51a, a first upper electrode 512b, a first piezoelectric body 512c, and a first vibration plate 262. The first vibration plate 262 includes a first elastic layer 262a and a first insulating layer 262b bonded together. The materials and other components of the first piezoelectric element 512 are the same as those in the first embodiment. The second piezoelectric element 722 includes a second lower electrode 722a, a second upper electrode 722b, a second piezoelectric body 722c, and a second vibration plate 292. The second vibration plate 292 includes a second elastic layer 292a and a second insulating layer 292b bonded together. The materials and other components of the second piezoelectric element 722 are the same as those in the first to third embodiments.

[0095] In this first modification, the thickness J2 of the second piezoelectric body 722c is greater than the thickness K2 of the first piezoelectric body 512c. The thicknesses of all other layers are substantially the same. Because the thickness J2 of the second piezoelectric body 722c is greater than the thickness K2 of the first piezoelectric body 512c, the neutral axis NA of the second piezoelectric element 722 is positioned higher than the neutral axis NA of the first piezoelectric element 512. As a result, similar to the third embodiment, in the pressure applying unit 70C2, the force generated by the first piezoelectric element 512 easily vibrates the first diaphragm 262. In addition, in the vibration detecting unit 70B2, the residual vibration of the ink received by the second diaphragm 292 transmits a strong force to the second piezoelectric element 722, thereby efficiently generating an electromotive force. This simultaneously satisfies the requirements of sufficiently increasing the pressure of the ink in the pressure chamber CC and accurately detecting the residual vibration of the ink in the vibration detecting chamber DB. As a result, the ink ejection throughput of the liquid ejection head 10 can be sufficiently increased.

[0096] Next, Modification 2 will be described. In this modification, the overall configuration is the same as in the first to third embodiments, but the method for making the height of the neutral axis NA of the second piezoelectric element 723 higher than the neutral axis NA of the first piezoelectric element 513 is different. In the third embodiment, the heights of the neutral axes of the two elements are adjusted by making the thicknesses of the second insulating layer 29b and the first insulating layer 26b different. However, in Modification 2, the thickness of the second insulating layer 293b of the second piezoelectric element 723 and the thickness of the first insulating layer 263b of the first piezoelectric element 513 are the same, and the heights of the neutral axes of the two elements are adjusted by making the thicknesses of the second elastic layer 293a and the first elastic layer 263a different.

[0097] The first vibration plate 263 of the first piezoelectric element 513 is formed by bonding a first elastic layer 263a and a first insulating layer 263b together. The materials and the like of each part of the first piezoelectric element 513 are the same as those in the first embodiment. The second vibration plate 293 of the second piezoelectric element 723 is formed by bonding a second elastic layer 293a and a second insulating layer 293b together. The materials and the like of each part of the second piezoelectric element 723 are the same as those in the first embodiment. Therefore, the reference numerals are the same as those in the first embodiment.

[0098] In Modification 2, the thickness K3 of the first elastic layer 263a of the first piezoelectric body 513c is greater than the thickness J3 of the second elastic layer 293a of the second piezoelectric body 723c. The thicknesses of all other layers are substantially the same. Because the thickness K3 of the first elastic layer 263a of the first piezoelectric body 513c is greater than the thickness J3 of the second elastic layer 293a of the second piezoelectric body 723c, the neutral axis NA of the second piezoelectric element 723 is positioned higher than the neutral axis NA of the first piezoelectric element 513. As a result, similar to the third embodiment, in the pressure applying unit 70C2, the force generated by the first piezoelectric element 513 easily vibrates the first diaphragm 263, and in the vibration detecting unit 70B2, the residual vibration of the second diaphragm 293 received from the ink transmits a strong force to the second piezoelectric element 723, thereby efficiently generating an electromotive force. This makes it possible to simultaneously satisfy the requirements of sufficiently increasing the pressure of the ink in the pressure chamber CC and accurately detecting the residual vibration of the ink in the vibration detection chamber DB, thereby enabling the ink ejection throughput of the liquid ejection head 10 to be sufficiently increased.

[0099] In addition to the above-described variations 1 and 2, various other structures for changing the position of the neutral axis NA are known, and it is possible to apply these techniques to achieve similar effects. For example, rather than changing the thickness of the first and second diaphragms, it is also possible to combine shapes that are convex in the Z1 direction (neutral axis at a low position) with shapes that are convex in the Z2 direction (neutral axis at a high position). Alternatively, it is also possible to adjust the height of the neutral axis by changing the materials and physical properties of the insulating layer and elastic layer that make up the diaphragm, for example, by appropriately adjusting the hardness of the insulating layer or the elastic modulus of the elastic layer.

[0100] For example, if the second insulating layer 292b is made of zirconium dioxide (ZrO2), and its hardness is made higher than that of the first insulating layer 262b by changing the sintering temperature or time of the zirconium dioxide, then even if the two have the same thickness, the thickness of the second insulating layer 292b will be equivalent to that of the first insulating layer 262b being thicker than the second insulating layer 262b, and the height of the neutral axis NA of the second piezoelectric element can be increased. Alternatively, the hardness may be changed in a similar manner by changing the binder or additive to achieve the desired characteristics.

[0101] D. Fourth embodiment: (D1) An embodiment in which the neutral axis on the pressure unit side is higher than that on the vibration detection unit side: In the third embodiment and its modified examples described above, as shown in FIGS. 14 and 15, the position (height) of the neutral axis of the first piezoelectric elements 511-513 of the liquid ejection head 10 is lower than the position (height) of the neutral axis of the second piezoelectric elements 721-723. In contrast, in the liquid ejection head 10 of the fourth embodiment, the relationship between the heights of the neutral axes of the two is reversed. FIG. 16 schematically shows the configuration of the vibration detection unit 70B3 and the pressure unit 70C3 of the liquid ejection head 10 of the fourth embodiment. Note that the overall configuration of the liquid ejection head 10 of the fourth embodiment is the same as that of the third embodiment, and therefore illustration and description of only the differences will be omitted.

[0102] In the liquid ejection head 10 of the fourth embodiment, the position (height) of the neutral axis of the first piezoelectric element 514 is lower than the position (height) of the neutral axis of the second piezoelectric element 724. Fig. 16 is an explanatory diagram showing a comparison of the shapes of the first piezoelectric element 514 in the pressure applying unit 70C3 and the second piezoelectric element 724 in the vibration detecting unit 70B3 in the fourth embodiment. The upper part of the diagram schematically shows the shapes of both elements as seen in the Y direction at cross sections in the XZ plane, and the lower part of the diagram schematically shows the cross sections as seen in the JJ and KK arrows of the diagram in the upper part.

[0103] As shown in the drawing, comparing the first diaphragm 264 of the first piezoelectric element 514 of the pressure applying unit 70C3 with the second diaphragm 294 of the second piezoelectric element 724 of the vibration detecting unit 70B3, the thickness K4 of the first insulating layer 264b constituting the first diaphragm 264 is greater than the thickness J4 of the second insulating layer 294b constituting the second diaphragm 294. The first piezoelectric element 514 and the second piezoelectric element 724 have substantially the same dimensions in at least the X direction, except for the thicknesses of the first insulating layers 264b and 294b. As a result, the Z direction position of the neutral axis of the first piezoelectric element 514 of the pressure applying unit 70C3 is higher than the Z direction position of the neutral axis of the second piezoelectric element 724 of the vibration detecting unit 70B3.

[0104] As previously mentioned, when a voltage is applied between the first lower electrode 514a and the first upper electrode 514b of the first piezoelectric element 514 in this state, compressive stress is generated in the first piezoelectric body 514c and the first insulating layer 261b, and tensile stress is generated in the first elastic layer 261a. However, because the thickness K4 of the first insulating layer 264b is greater than the thickness J4 of the second insulating layer 294b, the position of the neutral axis NA of the first piezoelectric element 514 is higher in the Z direction than the position of the neutral axis NA of the second piezoelectric element 724. Therefore, even if a predetermined voltage is applied between the first lower electrode 514a and the first upper electrode 514b of the first piezoelectric element 514 and the first piezoelectric body 514c is deformed, the force generated by the deformation of the first piezoelectric body 514c is smaller than in, for example, the first embodiment. On the other hand, since the position of the neutral axis NA of the second piezoelectric element 724 is low, the force acting on the second piezoelectric element 724 due to deformation of the second vibration plate 294 caused by residual vibration of the ink in the vibration detection chamber DB does not become excessive, and the electromotive force generated in the second piezoelectric element 724 due to the piezoelectric effect is also suppressed.

[0105] As a result, in the fourth embodiment, application of excessive force to the first elastic layer 264a can be suppressed. Therefore, the possibility of failure of the first elastic layer 264a can be reduced. Furthermore, because an appropriate reaction force is applied to the first piezoelectric element 514, deformation of the first piezoelectric element 514 can be suppressed, reducing the possibility of cracks occurring in the first piezoelectric element 514 due to excessive deformation. This reduces the possibility of failure of the first piezoelectric element 514, improving reliability and extending its lifespan. Furthermore, the second piezoelectric element 724 in the vibration detection unit 70B3 is deformed by a force that weakens the force caused by residual vibration of the ink in the vibration detection chamber DB, thereby suppressing the electromotive force generated by the piezoelectric effect. As a result, the possibility of excessive current being applied to wiring for detecting the electromotive force of the second piezoelectric element 724 can be reduced, reducing the possibility of damage to the wiring, such as burnout. The second piezoelectric element 724 used in the vibration detection unit 70B3 and the first piezoelectric element 514 used in the pressure application unit 70C3 can be configured to be substantially identical, which facilitates the manufacture of the liquid ejection head 10. In addition, the same effects as those of the first to third embodiments can be achieved with regard to the detection of ink ejection and residual vibration, and the absorption of pressure fluctuations in the absorption chamber DA.

[0106] In the fourth embodiment, the positions (heights) of the neutral axes of the first piezoelectric element 514 and the second piezoelectric element 724 are made different by making the thicknesses of the first insulating layer 264b and the second insulating layer 294b different. However, as explained in the modified example of the third embodiment, the thickness of the piezoelectric body, the thickness of the elastic layer, or the material or physical properties thereof, or the shape of the vibration plate may be made different, and similarly, the Z-direction position of the neutral axis of the first piezoelectric element 514 of the pressure applying unit 70C3 may be made higher than the Z-direction position of the neutral axis of the second piezoelectric element 724 of the vibration detecting unit 70B3.

[0107] Although the above description of the fourth embodiment did not mention the thickness of the third diaphragm 23 in the vibration absorbing section 70A, and therefore the thickness of the third insulating layer 23b, in this embodiment, the thickness of the third insulating layer 23b is the same as that of the adjacent first insulating layer 264b. This allows the third insulating layer 23b and the first insulating layer 264 to be manufactured integrally. The thickness of the third insulating layer 23b may be greater or smaller than the thickness K4 of the first insulating layer 264b or the thickness J4 of the first insulating layer 294b, or may be the same as either one, as long as the absorption characteristics of the liquid pressure in the absorption chamber DA can be ensured.

[0108] While multiple embodiments of the liquid ejection head have been described above, a liquid ejection device 11 can be easily realized by combining the various liquid ejection heads 10 described above with a control unit 20 that controls the ejection operation from the liquid ejection heads 10. FIG. 17 shows an example of the configuration of the liquid ejection device 11 as a printer that ejects ink to perform printing. The liquid ejection device 11 receives image data, etc., from an image output device (not shown) and prints the image data using the liquid ejection head 10 on printing paper P, which serves as a printing medium, attached to a platen 17. The liquid ejection device 11 is configured as a line printer. The platen 17 is transported by a paper transport mechanism 15. The ECU 12, which controls the entire liquid ejection device 11, ejects ink from the liquid ejection head 10 while transporting the printing paper P via the paper transport mechanism 15 and the control unit 20, thereby printing an image, etc., on the printing paper P. Other components constituting the printer are well known, and therefore illustrations and descriptions thereof are omitted. Such a liquid ejection device can handle various liquids, such as ink, water, alcohol, liquid fuel, and chemicals.

[0109] E. Other Embodiments: (1) A liquid ejection head according to the present disclosure includes a nozzle, a first piezoelectric element, a second piezoelectric element, a third piezoelectric element, a pressure chamber that applies pressure to eject liquid from the nozzle when the first piezoelectric element is driven, a detection chamber that detects residual vibrations of the pressure applied in the pressure chamber using the second piezoelectric element, an absorption chamber that absorbs vibrations of the pressure applied in the pressure chamber using the third piezoelectric element, and a wiring board that electrically connects the liquid ejection head to the outside. In this liquid ejection head, the first piezoelectric element is electrically connected to the wiring board, and the second piezoelectric element is electrically connected to the wiring board. When viewed from above, the third piezoelectric element, the first piezoelectric element, the wiring board, and the second piezoelectric element are arranged in this order. This allows liquid ejection, detection of residual vibrations, and absorption of unnecessary pressure fluctuations to be performed in parallel. Therefore, there is no need to stop liquid ejection or detection of residual vibrations while performing one of them, and there is no need to suppress the throughput of liquid ejection.

[0110] The liquid pressurized in the pressure chamber is ejected from the nozzle, but no other piezoelectric elements are arranged in the ejection direction. Therefore, when the third piezoelectric element, the first piezoelectric element, the wiring board, and the second piezoelectric element are deployed and arranged in a direction intersecting the liquid ejection direction so as not to unnecessarily lengthen the liquid supply path, the direction from above these elements corresponds to the up-down direction. When the liquid is ejected in the direction of gravity, the up-down direction approximately coincides with the direction of gravity. The third piezoelectric element, the first piezoelectric element, the wiring board, and the second piezoelectric element may be arranged linearly on the same plane, or may be arranged offset to the extent that the liquid supply path is not unnecessarily long. Furthermore, they do not have to be arranged on the same plane, but may be arranged within a predetermined range in the up-down direction.

[0111] Of the third piezoelectric element, the first piezoelectric element, the wiring board, and the second piezoelectric element, the first piezoelectric element and the second piezoelectric element receive wiring from the wiring board, so by arranging them in this manner, it is possible to reduce overlap of wiring from the wiring board to the piezoelectric elements and increase the degree of freedom in wiring. Note that in the arrangement of the third piezoelectric element, the first piezoelectric element, the wiring board, and the second piezoelectric element, either side may be the liquid supply side.

[0112] (2) In the above configuration, the third piezoelectric element may not be electrically connected to the wiring board. In this case, only the first piezoelectric element and the second piezoelectric element are wired to the wiring board, making it easy to separate the wiring from the wiring board to both piezoelectric elements.

[0113] (3) In the above configuration, the pressure chamber may be provided in plurality, the detection chamber may be provided individually for each of the pressure chambers, and the absorption chamber may be provided in common to the pressure chambers. This allows the second piezoelectric element provided in the detection chamber to accurately detect residual vibrations associated with pressure fluctuations in each pressure chamber that occur due to liquid ejection. On the other hand, providing a common absorption chamber allows the volume of the absorption chamber to be increased, allowing for efficient absorption of pressure fluctuations in the liquid and reducing variations between pressure chambers. Furthermore, if a vibration plate or the like is provided corresponding to the absorption chamber, the distance between the fixing points of the vibration plate can be increased, making it easier to vibrate the vibration plate or the like and achieving efficient vibration absorption.

[0114] (4) The above configurations (1) to (3) may further include a first wiring portion electrically connecting the first piezoelectric element to the wiring board and a second wiring portion electrically connecting the second piezoelectric element to the wiring board, the first wiring portion and the second wiring portion being laid in opposite directions from the wiring board. This prevents the first wiring portion and the second wiring portion from overlapping, facilitating the layout of the wiring portions and reducing crosstalk between the wiring portions. This prevents noise generated by energizing the first piezoelectric element for liquid ejection from being generated in the second wiring portion when energizing the first piezoelectric element, thereby preventing a decrease in the accuracy of detecting residual vibration using the second piezoelectric element. Note that as long as the first wiring portion and the second wiring portion are sufficiently separated, there may be portions laid in the same direction from the wiring board.

[0115] (5) In the configurations (1) to (4) above, the distance between the pressure chamber and the absorption chamber may be smaller than the distance between the pressure chamber and the detection chamber. This makes it difficult for pressure fluctuations on the absorption chamber side to affect the pressure chamber. If the distance between the pressure chamber and the detection chamber is large, it becomes easy to arrange a wiring board between them. Of course, the distance between the pressure chamber and the absorption chamber can also be larger than the distance between the pressure chamber and the detection chamber.

[0116] (6) In the configurations (1) to (5) above, the width of the pressure chamber in the extension direction may be larger than the width of the detection chamber in the extension direction and larger than the width of the absorption chamber in the extension direction. This allows the width of the pressure chamber CC in the extension direction of the pressure chamber to be long enough to ensure ejection performance, while the widths of the detection chamber and the absorption chamber are smaller than that, thereby prioritizing liquid ejection performance and enabling a compact liquid ejection head. Note that, since the functions of not only the pressure chamber but also the detection chamber and the absorption chamber are improved with larger widths, the widths of each may be increased within the limits of the size of the liquid ejection head. Note that, for example, by improving the performance of the first piezoelectric element, the width of the pressure chamber in the extension direction may be made smaller than the widths of the detection chamber and the absorption chamber in the extension direction.

[0117] (7) In the configurations (1) to (6) above, the width of the detection chamber in the extension direction may be larger than the width of the absorption chamber in the extension direction. This makes it easier to ensure the detection accuracy of residual vibrations within the dimensional constraints of the liquid ejection head. The area of ​​the absorption chamber that contributes to the ability to absorb pressure fluctuations can be ensured by the width of the absorption chamber in the direction intersecting the extension direction and the vertical direction. Therefore, pressure fluctuations can be sufficiently absorbed even if the extension direction width of the absorption chamber is not so large. Of course, it is also possible to improve absorption performance by widening the width of the absorption chamber.

[0118] (8) The configurations (1) to (7) above may further include a supply reservoir for supplying liquid to the pressure chamber and a discharge reservoir for discharging liquid from the pressure chamber, and the liquid may flow in the order of the supply reservoir, absorption chamber, pressure chamber, detection chamber, and discharge reservoir. Since the supply side is affected by pressure fluctuations from the pressure chamber as well as fluctuations in the supply pressure of the liquid, if the liquid flows in the above order, the absorption chamber can easily absorb pressure fluctuations on the supply side. Since the detection chamber is located far from the supply side, it is less affected by the supply pressure and it is easy to ensure the accuracy of detecting residual vibration.

[0119] (9) The configurations (1) to (7) above may further include a supply reservoir for supplying liquid to the pressure chamber and a discharge reservoir for discharging liquid from the pressure chamber, and the liquid may flow in the order of the supply reservoir, the detection chamber, the pressure chamber, the absorption chamber, and the discharge reservoir. In this way, a second piezoelectric element provided corresponding to the detection chamber can detect pressure fluctuations of the liquid on the supply side. If the pressure fluctuations of the liquid on the supply side significantly deviate from a predetermined value, an abnormality in a component related to the liquid supply can be suspected, and a warning of the possibility of an abnormality can be issued to prompt an appropriate response, or the use of the liquid ejection head can be stopped.

[0120] (10) In the configurations (1) to (9) above, the distance between the wiring board and the pressure chamber may be shorter than the distance between the wiring board and the detection chamber. Since the wiring board is disposed between the pressure chamber and the detection chamber, reducing the distance between either one increases the distance between the other. This shortens the wiring distance between the first piezoelectric element in the pressure chamber and the wiring board, reducing the electrical resistance of the wiring to the first piezoelectric element, making it easier to ensure sufficient current to the first piezoelectric element, which may require a large amount of energy for liquid ejection. Conversely, the distance between the wiring board and the detection chamber may be shorter than the distance between the wiring board and the pressure chamber. This reduces the resistance of the wiring to the second piezoelectric element, which detects residual vibration in the detection chamber, reducing attenuation of the electrical signal output by the second piezoelectric element in response to residual vibration and preventing a decrease in detection accuracy.

[0121] (11) In the configurations (1) to (10) above, the first piezoelectric element may include a first piezoelectric body, a first upper electrode provided on the first piezoelectric body, a first lower electrode provided below the first piezoelectric body, and a first diaphragm provided below the first lower electrode, the second piezoelectric element may include a second piezoelectric body, a second upper electrode provided on the second piezoelectric body, a second lower electrode provided below the second piezoelectric body, and a second diaphragm provided below the second lower electrode, and the third piezoelectric element may include a third piezoelectric body, a third upper electrode provided on the third piezoelectric body, a third lower electrode provided below the third piezoelectric body, and a third diaphragm provided below the third lower electrode. This allows the piezoelectric elements used in each section that ejects liquid, detects residual vibrations, and absorbs pressure fluctuations to have the same or similar configurations, thereby reducing manufacturing costs and standardizing handling.

[0122] (12) In the configuration of (11) above, the neutral axis of the second piezoelectric element may be positioned above the neutral axis of the first piezoelectric element. This allows the force generated in the first piezoelectric element that ejects liquid to be strengthened and transmitted to the first diaphragm, and also allows the force that deforms the second diaphragm due to residual vibration to be strengthened and transmitted to the second piezoelectric element. This makes it easier to meet the demands for improving both the liquid ejection capability and the residual vibration detection accuracy.

[0123] (13) On the other hand, in the configuration of (11) above, the neutral axis of the second piezoelectric element may be positioned below the neutral axis of the first piezoelectric element. This prevents excessive deformation of the first diaphragm due to the force generated in the first piezoelectric element that ejects liquid, and also prevents excessive force from being applied to the second piezoelectric element due to the force that deforms the second diaphragm due to residual vibration. This prevents damage to the components that eject liquid or detect residual vibration, making it easier to ensure reliability. It also makes it easier to reduce maintenance work.

[0124] (14) The present disclosure can be implemented as a liquid ejection device including any one of the liquid ejection heads described above in (1) to (13) and a control unit that controls the ejection operation from the liquid ejection head. This allows for a compact liquid ejection head that can output liquid, detect residual vibrations, and absorb pressure fluctuations with the liquid, thereby achieving a compact liquid ejection device with high reliability.

[0125] In each of the above embodiments, some of the configurations implemented by hardware may be replaced with software. At least a portion of the configurations implemented by software may also be implemented by a discrete circuit configuration. Furthermore, when some or all of the functions of the present disclosure are implemented by software, the software (computer program) may be provided in a form stored on a computer-readable recording medium. The term "computer-readable recording medium" is not limited to portable recording media such as floppy disks and CD-ROMs, but also includes internal storage devices within a computer, such as various RAMs and ROMs, and external storage devices fixed to a computer, such as a hard disk. In other words, the term "computer-readable recording medium" has a broad meaning, including any recording medium capable of fixing data packets, not just temporarily.

[0126] The present disclosure is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit thereof. For example, the technical features in the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0127] 10...liquid ejection head, 11...liquid ejection device, 18...circulation mechanism, 20...control unit, 21...nozzle substrate, 23...third diaphragm, 23a...third elastic layer, 23b...third insulating layer, 24...communicating plate, 25...pressure chamber substrate, 26...first diaphragm, 26a...first elastic layer, 26b...first insulating layer, 27...sealing plate, 27a...opening, 28...case, 29...second diaphragm, 29a...second elastic layer, 29b...second insulating layer, 40...flow path, 41A...supply flow path, 41B...discharge flow path, 42A...supply port, 42B...discharge port, 43A, 43B, 44A, 44B, 45A, 45B, 46A, 46B...flow paths, 47A to 47C...communicating flow paths, 51...first piezoelectric element, 51a...first lower electrode, 51b...first upper electrode, 51c...first piezoelectric element, 54...first wiring portion, 54a...electrode layer, 54b...first adhesion layer, 54c...first wiring layer, 55...VBS wiring, 59...insulating adhesive layer, 61...flexible wiring substrate, 62...control circuit, 70A...vibration absorbing portion, 70B, 70B2, 70B3...vibration detecting portion, 70C, 70C2, 70C3...pressure applying portion, 72...second piezoelectric element, 72a...second lower electrode, 72b...second upper electrode, 72c...second piezoelectric element, 73...third piezoelectric element, 73a...third lower electrode, 73b...third upper electrode, 73c...third piezoelectric element, 74...second wiring portion, 77A, 77B...compliance substrate

Claims

1. A liquid ejection head, A nozzle; a first piezoelectric element; A second piezoelectric element; a third piezoelectric element; a pressure chamber that applies pressure to eject liquid from the nozzle when the first piezoelectric element is driven; a detection chamber that detects residual vibration of the pressure applied in the pressure chamber by the second piezoelectric element; an absorption chamber that absorbs the vibration of the pressure applied in the pressure chamber by the third piezoelectric element; a wiring board that electrically connects the liquid ejection head to an outside, the first piezoelectric element is electrically connected to the wiring substrate; the second piezoelectric element is electrically connected to the wiring substrate; The liquid ejection head is arranged so that the third piezoelectric element, the first piezoelectric element, the wiring board, and the second piezoelectric element are aligned in this order when viewed from above and below.

2. The liquid ejection head according to claim 1 , wherein the third piezoelectric element is not electrically connected to the wiring substrate.

3. The pressure chamber is provided in plurality, the detection chambers are provided individually for the plurality of pressure chambers, The liquid ejection head according to claim 1 , wherein the absorption chamber is provided in common for the plurality of pressure chambers.

4. a first wiring portion that electrically connects the first piezoelectric element and the wiring substrate; a second wiring portion that electrically connects the second piezoelectric element and the wiring substrate, 2. The liquid ejection head according to claim 1, wherein the first wiring portion and the second wiring portion are laid out in opposite directions when viewed from the wiring board.

5. The liquid ejection head according to claim 1 , wherein the distance between the pressure chamber and the absorption chamber is smaller than the distance between the pressure chamber and the detection chamber.

6. 2. The liquid ejection head according to claim 1, wherein the width of the pressure chamber in the extension direction is larger than the width of the detection chamber in the extension direction and is larger than the width of the absorption chamber in the extension direction.

7. The liquid ejection head according to claim 1 , wherein the width of the detection chamber in the extension direction is larger than the width of the absorption chamber in the extension direction.

8. a supply reservoir for supplying liquid to the pressure chamber; a drain reservoir for draining liquid from the pressure chamber; The liquid ejection head according to claim 1 , wherein the liquid flows in the order of the supply reservoir, the absorption chamber, the pressure chamber, the detection chamber, and the discharge reservoir.

9. a supply reservoir for supplying liquid to the pressure chamber; a drain reservoir for draining liquid from the pressure chamber; The liquid ejection head according to claim 1 , wherein the liquid flows in the order of the supply reservoir, the detection chamber, the pressure chamber, the absorption chamber, and the discharge reservoir.

10. The liquid ejection head according to claim 1 , wherein the distance between the wiring board and the pressure chamber is smaller than the distance between the wiring board and the chamber.

11. the first piezoelectric element has a first piezoelectric body, a first upper electrode provided on the first piezoelectric body, a first lower electrode provided below the first piezoelectric body, and a first vibration plate provided below the first lower electrode; the second piezoelectric element has a second piezoelectric body, a second upper electrode provided on the second piezoelectric body, a second lower electrode provided below the second piezoelectric body, and a second vibration plate provided below the second lower electrode, 2. A liquid ejection head as described in claim 1, wherein the third piezoelectric element has a third piezoelectric body, a third upper electrode provided on the third piezoelectric body, a third lower electrode provided below the third piezoelectric body, and a third vibration plate provided below the third lower electrode.

12. The liquid ejection head according to claim 11 , wherein a neutral axis of the second piezoelectric element is positioned above a neutral axis of the first piezoelectric element.

13. The liquid ejection head according to claim 11 , wherein a neutral axis of the second piezoelectric element is located below a neutral axis of the first piezoelectric element.

14. A liquid ejection head according to any one of claims 1 to 13; a control unit for controlling a discharge operation from the liquid discharge head; A body ejection device having

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