Piezoelectric vibrator

Abstract

To provide a technique that makes it easy to realize a configuration in which an intermediate member that joins a piezoelectric vibrator to a base member and a conductive member that is electrically connected to the piezoelectric element are disposed at the nodes of a vibration plate.SOLUTION: An ultrasonic transducer 1 includes a piezoelectric element 20 and a vibration plate 21 bonded to one surface in the thickness direction of the piezoelectric element 20. The piezoelectric element 20 has a non-circular shape. The vibration plate 21 has a mark 21A indicating the circumferential position of the vibration plate 21 when viewed from one side in the thickness direction.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a piezoelectric vibrator. [Background technology]

[0002] Patent Document 1 discloses an ultrasonic generator equipped with a piezoelectric vibrator. This piezoelectric vibrator is formed by a piezoelectric element and a vibration plate bonded to the piezoelectric element. A lead wire is connected to the electrode of the piezoelectric element on the side opposite to the vibration plate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-64204 A Summary of the Invention [Problem to be solved by the invention]

[0004] The lead wires are preferably connected to the vibration nodes of the diaphragm. When the piezoelectric vibrator is joined to the base member via an intermediate member, the intermediate member is also preferably joined to the vibration nodes of the diaphragm. Since the nodes are annular, it is possible to place both the intermediate member and the lead wires at the nodes by arranging them with a circumferential offset. However, when attempting to place both the intermediate member and the lead wires at an annular node, the following problems arise.

[0005] When the piezoelectric vibrator is fixed to the intermediate member, the lead wires are hidden by the piezoelectric vibrator. As a result, the circumferential position of the lead wires cannot be grasped, and there is a risk that the lead wires will interfere with the intermediate member. In order to avoid such interference, it is possible to fix a conductive member such as a spring, which serves as a substitute for the lead wires, to the base member in advance, offset from the intermediate member. In this case, however, it is necessary to bond the piezoelectric vibrator to the intermediate member so that the piezoelectric element contacts the conductive member. If the piezoelectric element is non-circular, such as rectangular, there is a risk that the piezoelectric element will not contact the conductive member depending on the circumferential position of the piezoelectric element.

[0006] The present disclosure aims to provide a technique that makes it easy to realize a configuration in which an intermediate member that joins a piezoelectric vibrator to a base member and a conductive member that is electrically connected to the piezoelectric element are disposed at the nodes of a vibration plate. [Means for solving the problem]

[0007] [1] A piezoelectric element; a vibration plate bonded to one surface of the piezoelectric element in a thickness direction, The piezoelectric element is a non-circular piezoelectric vibrator, The diaphragm has a mark indicating a circumferential position of the diaphragm when viewed from one side in the thickness direction. Piezoelectric vibrator.

[0008] The vibration plate has a mark indicating the circumferential position of the vibration plate when viewed from one side in the thickness direction. Therefore, for example, when a conductive member such as a lead wire is connected to the piezoelectric element in advance, by grasping the circumferential positional relationship between the conductive member and the mark, it is possible to predict the circumferential position of the conductive member from the position of the mark. As a result, when the piezoelectric vibrator is joined to the base member via an intermediate member, it is easy to avoid the conductive member from interfering with the intermediate member. Also, even when a conductive member such as a spring is provided on the base member in advance, it is easy to arrange the piezoelectric element so that it contacts the conductive member. In other words, according to this configuration, it is easy to realize a configuration in which the intermediate member that joins the piezoelectric vibrator to the base member and the conductive member that is electrically connected to the piezoelectric element are arranged at the nodes of the vibration plate.

[0009] [2] The mark is a recess that is recessed inward from the outer edge of the diaphragm. The piezoelectric vibrator described in [1].

[0010] According to this configuration, the weight of the diaphragm can be reduced compared to a configuration without a recess.

[0011] [3] The recesses are provided in plurality and are arranged in a point-symmetrical relationship with each other. The piezoelectric vibrator described in [2].

[0012] According to this configuration, since the provision of the recess makes it difficult for imbalance in mass to occur, it is easy to avoid adverse effects on vibration caused by imbalance in mass.

[0013] [4] The piezoelectric element has a corner portion that protrudes outward when viewed in a plane perpendicular to the thickness direction, The recess of the vibration plate is disposed at a position offset from an extension of a straight line connecting the center of the piezoelectric element to the apex of the corner. A piezoelectric vibrator according to [2] or [3].

[0014] According to this configuration, the outer periphery of the piezoelectric element is less likely to protrude from the outer periphery of the diaphragm, so that it is possible to increase the design freedom, for example by increasing the diameter of the piezoelectric element and decreasing the diameter of the diaphragm. Effect of the Invention

[0015] According to the present invention, it is easy to realize a configuration in which the intermediate member that joins the piezoelectric vibrator to the base member and the conductive member that is electrically connected to the piezoelectric element are disposed at the nodes of the vibration plate. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a side view of the ultrasonic transducer of the first embodiment. [Diagram 2] FIG. 2 is a plan view of the ultrasonic transducer of the first embodiment. [Diagram 3] FIG. 3 is a side view of the piezoelectric vibrator according to the first embodiment. [Figure 4] FIG. 4 is a plan view of the piezoelectric vibrator according to the first embodiment. [Diagram 5] FIG. 5 is an explanatory diagram showing a state before the piezoelectric vibrator of the first embodiment is bonded to an intermediate member. [Figure 6] FIG. 6 is an explanatory diagram showing a state in which the piezoelectric vibrator of the first embodiment is misaligned in the circumferential direction. [Figure 7]FIG. 7 is a side view of the ultrasonic transducer of the second embodiment. [Figure 8] FIG. 8 is a plan view of the ultrasonic transducer of the second embodiment. [Figure 9] FIG. 9 is an explanatory diagram showing a state before the piezoelectric vibrator of the second embodiment is bonded to an intermediate member. [Figure 10] FIG. 10 is an explanatory diagram showing a state in which the piezoelectric vibrator of the second embodiment is misaligned in the circumferential direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The piezoelectric vibrator and ultrasonic transducer of the present disclosure are used, for example, in ultrasonic distance sensors, ultrasonic oscillation devices, haptic devices, parametric speakers, and the like.

[0018] 1. First embodiment 1-1. Structure of ultrasonic transducer 1 The ultrasonic transducer 1 shown in FIGS. 1 and 2 generates ultrasonic waves when a drive signal is given, and converts ultrasonic waves into an electrical signal when it receives ultrasonic waves.

[0019] The ultrasonic transducer 1 includes a piezoelectric vibrator 11, a base member 12, an intermediate member 13, a first lead wire 14, and a second lead wire 15.

[0020] The piezoelectric vibrator 11 generates ultrasonic waves when a drive signal is applied, and generates a voltage when an ultrasonic wave is received. As shown in Fig. 3 and Fig. 4, the piezoelectric vibrator 11 includes a piezoelectric element 20, a diaphragm 21, and a resonator 22.

[0021] The piezoelectric element 20 has a plate shape. The shape of the piezoelectric element 20 is non-circular when viewed from the thickness direction of the piezoelectric element 20 (hereinafter also simply referred to as the "thickness direction"). In this embodiment, the shape of the piezoelectric element 20 is rectangular. The piezoelectric element 20 has a piezoelectric body 23 and electrodes 24 and 25. The piezoelectric body 23 has a plate shape. The piezoelectric body 23 is made of ceramics such as lead zirconate titanate (PZT) and potassium sodium niobate (KNN). The electrodes 24 and 25 have a plate shape. The electrode 24 is provided on one surface of the piezoelectric body 23 in the thickness direction. The electrode 24 constitutes one surface of the piezoelectric element 20 in the thickness direction. The electrode 25 is provided on the surface of the piezoelectric body 23 on the other side in the thickness direction. The electrode 25 constitutes the surface of the piezoelectric element 20 on the other side in the thickness direction. The vibration plate 21 is bonded to the surface of the piezoelectric element 20 on one side in the thickness direction. As a result, the electrode 24 is electrically connected to the vibration plate 21. In this specification, the term "joining" is a concept that includes not only a direct joining configuration, but also a joining configuration via another member. The piezoelectric element 20 is joined to the vibration plate 21 so as to be laminated thereon.

[0022] The vibration plate 21 is plate-shaped. When viewed from one side in the thickness direction, the vibration plate 21 has a circular shape with a partially recessed outer edge. When viewed from one side in the thickness direction, the vibration plate 21 covers the entire piezoelectric element 20. The vibration plate 21 is conductive. The vibration plate 21 is made of a metal material such as 42 alloy (42Ni-Fe). The vibration plate 21 has a mark 21A that indicates the circumferential position of the vibration plate 21 when viewed from one side in the thickness direction.

[0023] The mark 21A is a recess 21A recessed inward from the outer edge of the vibration plate 21. The entire recess 21A is disposed outside the node 26 of the vibration plate 21. A plurality of recesses 21A (four in this embodiment) are provided. The plurality of recesses 21A are disposed in a positional relationship that is point symmetrical with respect to one another. The plurality of recesses 21A are disposed at equal intervals in the circumferential direction. The above-mentioned piezoelectric element 20 has a corner 20A that protrudes outward when viewed in a plane perpendicular to the thickness direction. The recess 21A is disposed at a position shifted from an extension line EL of a straight line that connects the center C of the piezoelectric element 20 to the vertex of the corner 20A.

[0024] The resonator 22 is bonded to one surface of the diaphragm 21 in the thickness direction. The resonator 22 is cone-shaped and expands toward one side in the thickness direction. The resonator 22 resonates with the vibration of the diaphragm 21 to generate ultrasonic waves. The resonator 22 has a function of increasing the efficiency of sound wave transmission from the diaphragm 21, which is excited in response to periodic power supply to the piezoelectric element 20. The resonator 22 is made of metal, such as an aluminum alloy.

[0025] The above-mentioned vibration plate 21 vibrates so as to generate an annular (more specifically, circular) node 26. The vibration plate 21 generates only one annular node 26. The node 26 is a portion where the amount of displacement in the plate thickness direction when the vibration plate 21 vibrates is the smallest or a portion where there is no vibration. The node 26 is uniquely determined by the shapes and materials of the vibration plate 21, the piezoelectric element 20, and the resonator 22. Note that in FIG. 1, the piezoelectric element 20 is exaggerated and shown to be large, but in reality, it is much smaller than the vibration plate 21 and the resonator 22. For this reason, the position of the node 26 is generally determined by the shapes and materials of the vibration plate 21 and the resonator 22, and the shape and material of the piezoelectric element 20 have little effect on the determination of the position of the node 26. The outer periphery of the vibration plate 21 is a free end. In other words, the ultrasonic transducer 1 is a so-called open type, and is more likely to vibrate than a closed type in which the outer periphery of the vibration plate 21 is fixed. In a planar direction perpendicular to the plate thickness direction, the nodes 26 are generated inside the outer periphery and outside the center of the diaphragm 21. The vibration of the diaphragm 21 increases from the nodes 26 toward the outer periphery and increases from the nodes 26 toward the center.

[0026] 1, the base member 12 is provided on the other side in the thickness direction of the piezoelectric vibrator 11. The base member 12 has insulating properties. The base member 12 is configured as, for example, a resin base. The base member 12 has a plate shape.

[0027] As shown in FIG. 1, the intermediate member 13 is disposed between the piezoelectric element 20 and the base member 12. The intermediate member 13 is bonded to both the piezoelectric element 20 and the base member 12. The intermediate member 13 has insulating properties and elasticity. The intermediate member 13 has a lower Young's modulus than the base member 12. The intermediate member 13 is made of, for example, rubber such as silicone rubber, or resin such as a silicon-based adhesive. As shown in FIG. 2, the intermediate member 13 is disposed along the node 26. The intermediate member 13 has an annular shape (more specifically, an annular shape). At least a part of the intermediate member 13 is disposed at a position overlapping the node 26 when viewed from one side in the thickness direction. For example, the intermediate member 13 is disposed so that the vibration node 26 of the vibration plate 21 is disposed between an inscribed circle inscribed in the intermediate member 13 and a circumscribed circle circumscribed in the intermediate member 13 when viewed from one side in the thickness direction.

[0028] The first lead wire 14 is a coated electric wire. As shown in FIG. 1, the first lead wire 14 has an elongated first conductor 14A and a first coating 14B that covers the outer circumference of the first conductor 14A. The first conductor 14A is exposed at the tip of the first lead wire 14. The first conductor 14A of the first lead wire 14 is soldered to the electrode 25 of the piezoelectric element 20 using a first solder 16. This electrically connects the first lead wire 14 to the electrode 25. It is preferable that at least a part of the first solder 16 is disposed at a position overlapping the node 26 when viewed from one side in the thickness direction. The first coating 14B of the first lead wire 14 is fixed to the base member 12.

[0029] The second lead wire 15 is a coated electric wire. As shown in FIG. 1, the second lead wire 15 has an elongated second conductor 15A and a second coating 15B that covers the outer circumference of the second conductor 15A. The second conductor 15A is exposed at the tip of the second lead wire 15. The second conductor 15A of the second lead wire 15 is soldered to the diaphragm 21 using the second solder 17. This electrically connects the second lead wire 15 to the diaphragm 21 and the electrode 24. It is preferable that at least a part of the second solder 17 is arranged at a position overlapping the node 26 when viewed from one side in the thickness direction. The second coating 15B of the second lead wire 15 is fixed to the base member 12.

[0030] 1-2. Manufacturing method of ultrasonic transducer 1 First, the piezoelectric vibrator 11, the base member 12, the intermediate member 13, the first lead wire 14, and the second lead wire 15 are prepared. As shown in FIG. 5, the intermediate member 13 is joined to a surface of the base member 12 on one side in the thickness direction. The first lead wire 14 is soldered to the electrode 25 of the piezoelectric element 20. The second lead wire 15 is soldered to the vibration plate 21. The piezoelectric vibrator 11 is disposed on one side in the thickness direction with respect to the intermediate member 13. Then, the circumferential position of the recess 21A is adjusted to be the position shown in FIG. 2. If the circumferential position of the recess 21A were the position shown in FIG. 6, the soldered portion of the first lead wire 14 would interfere with the intermediate member 13. Therefore, by adjusting the circumferential position of the recess 21A to the position shown in Figure 2 and then joining the piezoelectric vibrator 11 to the intermediate member 13, the first lead wire 14, the first solder 16, the second lead wire 15, and the second solder 17 are less likely to interfere with the intermediate member 13.

[0031] 1-3.Effects of the piezoelectric vibrator 11 The vibration plate 21 has a mark 21A that indicates the circumferential position of the vibration plate 21 when viewed from one side in the thickness direction. Therefore, by grasping the circumferential positional relationship between the first lead wire 14 and the second lead wire 15 and the mark 21A, it is possible to predict the circumferential positions of the first lead wire 14 and the second lead wire 15 from the position of the mark 21A. As a result, when the piezoelectric vibrator 11 is joined to the base member 12 via the intermediate member 13, it is easy to avoid the first lead wire 14 and the second lead wire 15 from interfering with the intermediate member 13.

[0032] Furthermore, the mark 21A is a recess 21A recessed inward from the outer edge of the diaphragm 21. According to this configuration, the weight of the diaphragm 21 can be reduced compared to a configuration without the recess 21A.

[0033] Furthermore, a plurality of recesses 21A are provided and arranged in a positional relationship that is point symmetrical with respect to each other. With this configuration, the provision of recesses 21A makes it difficult for mass imbalance to occur, and therefore it is easy to avoid adverse effects on vibration caused by mass imbalance.

[0034] Furthermore, recess 21A of vibration plate 21 is disposed at a position offset from extension line EL of a straight line connecting center C of piezoelectric element 20 to the apex of corner 20A. With this configuration, the outer periphery of piezoelectric element 20 is less likely to protrude from the outer periphery of vibration plate 21, so that design freedom can be increased, for example, by increasing the diameter of piezoelectric element 20 or decreasing the diameter of vibration plate 21.

[0035] 2. Second embodiment In the second embodiment, an example will be described in which a first spring 214 and a second spring 215 are used instead of the first lead wire 14 and the second lead wire 15. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0036] 2-1. Configuration of ultrasonic transducer 201 The ultrasonic transducer 201 shown in FIGS. 7 and 8 generates ultrasonic waves when a drive signal is given, and converts ultrasonic waves into an electrical signal when the ultrasonic transducer 201 receives ultrasonic waves.

[0037] The ultrasonic transducer 201 includes a piezoelectric vibrator 11, a base member 212, an intermediate member 13, a first spring 214, a second spring 215, a first terminal 216, and a second terminal 217.

[0038] Holes 212A and 212B penetrating in the thickness direction are formed in the base member 212. The base member 212 is otherwise common to the base member 12 described in the first embodiment.

[0039] The first spring 214 is a compression coil spring. The first spring 214 is inserted into the hole 212A. An end of the first spring 214 on one side in the thickness direction contacts the electrode 25 of the piezoelectric element 20. An end of the first spring 214 on the other side in the thickness direction contacts the first terminal 216. The first terminal 216 is fixed to the base member 212. The first spring 214 is disposed in a compressed state between the electrode 25 of the piezoelectric element 20 and the first terminal 216. At least a part of the contact portion of the first spring 214 with the electrode 25 is preferably disposed at a position overlapping the node 26 when viewed from one side in the thickness direction.

[0040] The second spring 215 is a compression coil spring. The second spring 215 is inserted into the hole 212B. An end of the second spring 215 on one side in the thickness direction contacts the diaphragm 21. An end of the second spring 215 on the other side in the thickness direction contacts the second terminal 217. The second terminal 217 is fixed to the base member 212. The second spring 215 is disposed in a compressed state between the diaphragm 21 and the second terminal 217. At least a part of the contact portion of the second spring 215 with the diaphragm 21 is preferably disposed at a position overlapping the node 26 when viewed from one side in the thickness direction.

[0041] 2-2. Manufacturing method of ultrasonic transducer 201 First, the piezoelectric vibrator 11, the base member 212, the intermediate member 13, the first spring 214, the second spring 215, the first terminal 216, and the second terminal 217 are prepared. As shown in Fig. 9, the first terminal 216 is fixed to the base member 212 so as to close the other side in the thickness direction of the hole 212A. The second terminal 217 is fixed to the base member 212 so as to close the other side in the thickness direction of the hole 212B. The first spring 214 is inserted into the hole 212A. The second spring 215 is inserted into the hole 212B. The intermediate member 13 is joined to a surface of the base member 212 on one side in the thickness direction.

[0042] The piezoelectric vibrator 11 is disposed on one side in the thickness direction with respect to the intermediate member 13. Then, the circumferential position of the recess 21A is adjusted to the position shown in Fig. 8. If the circumferential position of the recess 21A is the position shown in Fig. 10, the first spring 214 does not contact the electrode 25 of the piezoelectric element 20. Therefore, by adjusting the circumferential position of the recess 21A to the position shown in Fig. 8 and then bonding the piezoelectric vibrator 11 to the intermediate member 13, the first spring 214 becomes more likely to contact the electrode 25 of the piezoelectric element 20 and the second spring 215 becomes more likely to contact the vibration plate 21.

[0043] 2-3.Effects of the piezoelectric vibrator 11 The vibration plate 21 has a mark 21A indicating the circumferential position of the vibration plate 21 when viewed from one side in the thickness direction. Therefore, by grasping the circumferential positional relationship between the first spring 214 and the second spring 215 and the mark 21A, it is possible to predict the circumferential positions of the first spring 214 and the second spring 215 from the position of the mark 21A. As a result, when the piezoelectric vibrator 11 is joined to the base member 212 via the intermediate member 13, the electrode 25 of the piezoelectric element 20 can be easily arranged to contact the first spring 214.

[0044] <Other embodiments> The present invention is not limited to the embodiments described above and in the drawings, and the following embodiments are also included in the technical scope of the present invention. In addition, the various features of the above-mentioned embodiments and the embodiments to be described later may be combined in any combination as long as they are not contradictory.

[0045] The shape of the piezoelectric element is not limited to a rectangle as long as it is non-circular. For example, the shape of the piezoelectric element may be a rectangle with a recess formed on at least one side, a shape with a through hole formed, or a polygon other than a square.

[0046] The mark is not limited to a recessed portion, and may be, for example, a pattern drawn on the diaphragm with a laser or the like.

[0047] It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is not limited to the embodiments disclosed herein, and is intended to include all modifications within the scope indicated by the claims or within the scope equivalent to the claims. [Explanation of symbols]

[0048] 1...Ultrasonic transducer 11...Piezoelectric vibrator 12...Base member 13...Intermediate part 14…First lead wire 14A…First conductor 14B…First coating 15…Second lead wire 15A…Second conductor 15B…Second coating 20...Piezoelectric element 20A…Corner 21...Diaphragm 21A…Mark (recess) 22...Resonator 23...Piezoelectric body 24...Electrode 25...Electrode Verse 26 201...Ultrasonic transducer 212...Base member 212A…hole 212B…hole 214…First spring 215…Second spring 216...1st terminal 217…Second terminal C…center EL…Extension line

Claims

1. A piezoelectric element; a vibration plate bonded to one surface of the piezoelectric element in a thickness direction, The piezoelectric element is a non-circular piezoelectric vibrator, The diaphragm has a mark indicating a circumferential position of the diaphragm when viewed from one side in the thickness direction. Piezoelectric vibrator.

2. The mark is a recess recessed inward from the outer edge of the diaphragm. The piezoelectric vibrator according to claim 1 .

3. The recesses are provided in plurality and are arranged in a point-symmetrical relationship with each other. The piezoelectric vibrator according to claim 2 .

4. the piezoelectric element has a corner portion that protrudes outward when viewed in a plane perpendicular to the thickness direction, The recess of the vibration plate is disposed at a position offset from an extension of a straight line connecting the center of the piezoelectric element to the apex of the corner. The piezoelectric vibrator according to claim 2 or 3.

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