Ultrasonic sensor

Abstract

To enable wiring without using a metal plate.SOLUTION: An ultrasonic sensor comprises: a piezoelectric element 11 including a piezoelectric body 111, a first electrode 112 arranged on one surface in one direction of the piezoelectric body 111, and a second electrode 113 arranged on the other surface on the one direction of the piezoelectric body 111, so as to perform a displacement other than a vertical displacement; a first wiring 12 electrically connected to the first electrode 112; a second wiring 13 electrically connected to the second electrode 113; and an acoustic matching layer 14 whose one surface is connected to one surface in a direction vertical to the one direction of the piezoelectric element 11.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an ultrasonic sensor using a piezoelectric element. [Background technology]

[0002] In an ultrasonic sensor using a piezoelectric element, ultrasonic waves are generated by applying a voltage to a piezoelectric body sandwiched between electrodes. An example of the configuration of this conventional ultrasonic sensor 1b will be described with reference to FIG.

[0003] A conventional ultrasonic sensor 1b includes, for example, a piezoelectric element 11b, a metal plate 15b, a first wiring 12b, a second wiring 13b, and an acoustic matching layer 14b, as shown in FIG.

[0004] The piezoelectric element 11b is a piezoelectric element that performs vertical displacement (also generally referred to as the 33 direction). As shown in FIG. 3, the piezoelectric element 11b has a piezoelectric body 111b, a first electrode 112b, and a second electrode 113b. The first electrode 112b is a film-like electrode provided on the upper surface of the piezoelectric body 111b. The second electrode 113b is a film-like electrode provided on the lower surface of the piezoelectric body 111b.

[0005] The metal plate 15b is a metal plate member having one surface connected to one electrode of the piezoelectric element 11b (the second electrode 113b in FIG. 3).

[0006] The first wiring 12b is electrically connected to the first electrode 112b. In Fig. 3, the first wiring 12b is electrically connected to the first electrode 112b by having one end directly soldered to the first electrode 112b. In Fig. 3, reference numeral 121b denotes solder.

[0007] The second wiring 13b is electrically connected to the second electrode 113b. In Fig. 3, one end of the second wiring 13b is soldered to one surface of the metal plate 15b, and thus the second wiring 13b is electrically connected to the second electrode 113b via the metal plate 15b. In Fig. 3, reference numeral 131b denotes solder.

[0008] The acoustic matching layer 14b is a member having one surface connected to the other surface of the metal plate 15b.

[0009] Thus, the conventional ultrasonic sensor 1b uses a piezoelectric element 11b that performs vertical displacement. In this case, the direction of the vertical displacement and the direction in which ultrasonic waves are generated are the same, that is, the direction in which the electrodes of the piezoelectric element 11b are located and the direction in which ultrasonic waves are generated are the same. Therefore, in this case, the ultrasonic sensor 1b requires wiring to the ultrasonic wave generating surface. In addition, in FIG. 3, the thick arrow indicates the direction in which ultrasonic waves are generated. Here, wiring to the first electrode 112b can be performed without any problem. On the other hand, when wiring to the second electrode 113b, it is necessary to attach an acoustic matching layer 14b to the second electrode 113b side, and since the second electrode 113b is in a film form (for example, about 100 um), it is difficult to perform wiring directly to the second electrode 113b. Therefore, in the conventional ultrasonic sensor 1b, a metal plate 15b is provided between the piezoelectric element 11b and the acoustic matching layer 14b, and wiring is performed to this metal plate 15b. In addition, in FIG. 3, the dashed arrow indicates an electrical path from the soldering point to the second electrode 113b.

[0010] For example, in Patent Document 1, a cap is made of a metal plate, and a voltage is applied from a terminal plate connected to the cap. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2001-349757 A Summary of the Invention [Problem to be solved by the invention]

[0012] As described above, in the conventional ultrasonic sensor 1b, the metal plate 15b is provided between the piezoelectric element 11b and the acoustic matching layer 14b, and wiring is performed to this metal plate 15b. In this case, however, adhesive layers using an adhesive material are formed between the piezoelectric element 11b and the metal plate 15b, and between the metal plate 15b and the acoustic matching layer 14b, respectively, and it is required that the adhesion of these adhesive layers is stable over the long term. That is, it is necessary that electrical connection is established in these adhesive layers, and that the fixation of the adhesive layers does not become unstable due to vibration. Therefore, it is desirable to have a small number of adhesive layers.

[0013] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide an ultrasonic sensor that allows wiring without using a metal plate. [Means for solving the problem]

[0014] The ultrasonic sensor of the present disclosure is characterized in that it comprises a piezoelectric element having a piezoelectric body, a first electrode provided on one surface of the piezoelectric body in one direction, and a second electrode provided on the other surface of the piezoelectric body in the one direction, and performing a displacement other than vertical displacement, a first wiring electrically connected to the first electrode, a second wiring electrically connected to the second electrode, and an acoustic matching layer having one surface connected to one surface of the piezoelectric element in a direction perpendicular to the one direction. Effect of the Invention

[0015] According to the present disclosure, since it is configured as described above, wiring can be performed without using a metal plate. [Brief description of the drawings]

[0016] [Figure 1] 1 is a diagram illustrating a configuration example of an ultrasonic sensor according to a first embodiment. [Diagram 2] 11 is a diagram illustrating a configuration example of an ultrasonic sensor according to a second embodiment. FIG. [Diagram 3] FIG. 1 is a diagram illustrating an example of the configuration of a conventional ultrasonic sensor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, the embodiments will be described in detail with reference to the drawings. Embodiment 1 FIG. 1 is a diagram showing an example of the configuration of an ultrasonic sensor 1 according to the first embodiment. The ultrasonic sensor 1 is a sensor that uses a piezoelectric element 11, and generates ultrasonic waves by applying a voltage to a piezoelectric body 111 sandwiched between electrodes. As shown in Fig. 1, the ultrasonic sensor 1 according to the first embodiment includes a piezoelectric element 11, a first wiring 12, a second wiring 13, and an acoustic matching layer 14. In Fig. 1, the thick arrow indicates the direction in which ultrasonic waves are generated.

[0018] The piezoelectric element 11 is a piezoelectric element 11 that performs lateral displacement (also generally referred to as the 31 direction). The piezoelectric element 11 has a piezoelectric body 111, a first electrode 112, and a second electrode 113. The first electrode 112 is a film-like electrode provided on one surface of the piezoelectric body 111 in one direction (the left surface in FIG. 1). The second electrode 113 is a film-like electrode provided on the other surface of the piezoelectric body 111 in one direction (the right surface in FIG. 1).

[0019] It is preferable that the piezoelectric element 11 is configured so that it can vibrate easily. For example, the piezoelectric element 11 may have the above configuration by making the piezoelectric body 111 thinner than a general piezoelectric body. Also, for example, the piezoelectric element 11 may have the above configuration by forming mesh-like grooves on both sides in a direction perpendicular to the one direction.

[0020] The first wiring 12 is electrically connected to the first electrode 112 . At this time, in the ultrasonic sensor 1 according to the first embodiment, one end of the first wiring 12 is directly soldered to the first electrode 112, so that the first wiring 12 is electrically connected to the first electrode 112. In addition, in Fig. 1, the reference numeral 121 denotes solder.

[0021] The second wiring 13 is electrically connected to the second electrode 113 . At this time, in the ultrasonic sensor 1 according to the first embodiment, one end of the second wiring 13 is directly soldered to the second electrode 113, so that the second wiring 13 is electrically connected to the second electrode 113. In addition, in Fig. 1, the reference numeral 131 denotes solder.

[0022] It is preferable that the first wiring 12 and the second wiring 13 are soldered symmetrically. In other words, if the first wiring 12 and the second wiring 13 are not symmetrical, it becomes difficult to obtain ideal vibration in the ultrasonic sensor 1. On the other hand, solder has weight. Therefore, depending on the connection points of the first wiring 12 and the second wiring 13, the symmetry of the first wiring 12 and the second wiring 13 may be lost. Therefore, for example, as shown in FIG. 1, the first wiring 12 and the second wiring 13 are desirably soldered to the points of the first electrode 112 and the second electrode 113 that are in contact with the acoustic matching layer 14.

[0023] One surface of the acoustic matching layer 14 is connected to one surface (the lower surface in FIG. 1) of the piezoelectric element 11 in a direction perpendicular to the above-mentioned one direction.

[0024] The adhesive used to bond the piezoelectric element 11 and the acoustic matching layer 14 is a polymer and therefore has viscoelasticity. This viscoelasticity may absorb vibrations depending on the frequency, in which case the vibrations themselves become smaller and the output of the ultrasonic sensor 1 becomes smaller. For this reason, it is desirable to use an adhesive with viscoelasticity outside the resonant frequency according to the vibration characteristics of the piezoelectric element 11.

[0025] In this way, in the ultrasonic sensor 1 according to the first embodiment, a piezoelectric element 11 that performs lateral displacement is used as the piezoelectric element 11. As a result, the direction of lateral displacement and the direction in which ultrasonic waves are generated are different directions, that is, the direction in which the electrodes of the piezoelectric element 11 are located and the direction in which ultrasonic waves are generated are different directions. Therefore, in the ultrasonic sensor 1 according to the first embodiment, wiring is performed on a surface other than the ultrasonic wave generation surface, and it is possible to directly wire the electrodes. Therefore, in the ultrasonic sensor 1 according to embodiment 1, the metal plate 15b as in the conventional technology is not necessary, and the number of adhesive layers using adhesive is reduced, so that it is possible to ensure long-term stability compared to the conventional technology.

[0026] Furthermore, when a piezoelectric element 11 that performs lateral displacement is used as the piezoelectric element 11, there is a problem that the displacement becomes small and the output of the ultrasonic sensor 1 becomes small. Therefore, in the ultrasonic sensor 1 according to the first embodiment, it is desirable that the piezoelectric element 11 be configured so as to be easily vibrated. For example, the piezoelectric element 11 may have the above configuration by making the piezoelectric body 111 thinner than a general piezoelectric body. Also, for example, the piezoelectric element 11 may have the above configuration by forming mesh-like grooves on both sides in a direction perpendicular to the one direction. As a result, in the ultrasonic sensor 1 according to the first embodiment, the displacement of the piezoelectric element 11 increases, and the output increases.

[0027] 1 shows a case where a piezoelectric element 11 that performs horizontal displacement is used as the piezoelectric element 11. However, the present invention is not limited to this, and in the ultrasonic sensor 1 according to the first embodiment, a piezoelectric element that performs a displacement other than vertical displacement may be used as the piezoelectric element 11. For example, the ultrasonic sensor 1 according to the first embodiment may use a piezoelectric element that undergoes sliding displacement (also generally referred to as 15-direction) as the piezoelectric element 11. In this case as well, the direction of the sliding displacement and the direction in which ultrasonic waves are generated are different directions, that is, the direction in which the electrodes of the piezoelectric element 11 are located and the direction in which ultrasonic waves are generated are different directions, so that wiring is performed on a surface other than the ultrasonic wave generation surface, and wiring can be performed directly on the electrodes. As a result, even in this case, the metal plate 15b as in the conventional case is no longer necessary, and the number of adhesive layers using adhesive is reduced, making it possible to ensure long-term stability compared to the conventional case.

[0028] As described above, according to this embodiment 1, the ultrasonic sensor 1 has a piezoelectric body 111, a first electrode 112 provided on one surface of the piezoelectric body 111 in one direction, and a second electrode 113 provided on the other surface of the piezoelectric body 111 in the one direction, and is equipped with a piezoelectric element 11 that performs a displacement other than vertical displacement, a first wiring 12 electrically connected to the first electrode 112, a second wiring 13 electrically connected to the second electrode 113, and an acoustic matching layer 14 having one surface connected to one surface of the piezoelectric element 11 in a direction perpendicular to the one direction. In the ultrasonic sensor 1 according to the first embodiment, the first wiring 12 is soldered to the first electrode 112 , and the second wiring 13 is soldered to the second electrode 113 . In addition, in the ultrasonic sensor 1 according to the first embodiment, for example, a piezoelectric element that performs lateral displacement or a piezoelectric element that performs sliding displacement is used as the piezoelectric element 11. As a result, the ultrasonic sensor 1 according to the first embodiment can be wired without using the metal plate 15b.

[0029] Embodiment 2 In the ultrasonic sensor 1 according to the first embodiment, the first wiring 12 is soldered to the first electrode 112, so that the first wiring 12 is electrically connected to the first electrode 112, and the second wiring 13 is soldered to the second electrode 113, so that the second wiring 13 is electrically connected to the second electrode 113. In contrast, in the ultrasonic sensor 1 according to the second embodiment, the first wiring 12 is connected to the first metal thin film 15 by a conductive adhesive, so that the first wiring 12 is electrically connected to the first electrode 112 via the first metal thin film 15, and the second wiring 13 is connected to the second metal thin film 16 by a conductive adhesive, so that the second wiring 13 is electrically connected to the second electrode 113 via the second metal thin film 16.

[0030] Fig. 2 is a diagram showing a configuration example of an ultrasonic sensor 1 according to embodiment 2. In the ultrasonic sensor 1 according to embodiment 2 shown in Fig. 2, a first metal thin film 15 and a second metal thin film 16 are added to the ultrasonic sensor 1 according to embodiment 1 shown in Fig. 1. The other configurations of the ultrasonic sensor 1 according to embodiment 2 shown in FIG. 2 are similar to the configuration example of the ultrasonic sensor 1 according to embodiment 1 shown in FIG. 1, and the same symbols are used and only the different parts will be described.

[0031] The first metal thin film 15 is provided on one surface (the surface facing the piezoelectric element 11, the upper surface in FIG. 2) of the acoustic matching layer 14. This first metal thin film 15 is formed, for example, by patterning on one surface of the acoustic matching layer 14. The first metal thin film 15 is electrically connected to the first electrode 112 by connecting the piezoelectric element 11 to the acoustic matching layer 14 via an adhesive.

[0032] The second metal thin film 16 is provided on one surface (the surface facing the piezoelectric element 11, the upper surface in FIG. 2) of the acoustic matching layer 14. This second metal thin film 16 is formed, for example, by patterning on one surface of the acoustic matching layer 14. The second metal thin film 16 is electrically connected to the second electrode 113 by connecting the piezoelectric element 11 to the acoustic matching layer 14 via an adhesive.

[0033] In addition, in Fig. 2, reference numeral 17 denotes an adhesive material. As shown in Fig. 2, the adhesive material is applied between the piezoelectric body 111 of the piezoelectric element 11 and the acoustic matching layer 14.

[0034] In the ultrasonic sensor 1 according to the second embodiment, one end of the first wiring 12 is connected to the first metal thin film 15 by a conductive adhesive. As a result, the first wiring 12 is electrically connected to the first electrode 112 via the first metal thin film 15. In addition, in FIG. 2, reference numeral 122 denotes a conductive adhesive.

[0035] In the ultrasonic sensor 1 according to the second embodiment, one end of the second wiring 13 is connected to the second metal thin film 16 by a conductive adhesive. As a result, the second wiring 13 is electrically connected to the second electrode 113 via the second metal thin film 16. In addition, in FIG. 2, reference numeral 132 denotes a conductive adhesive.

[0036] In this way, in the ultrasonic sensor 1 according to the second embodiment, a piezoelectric element 11 that performs lateral displacement is used as the piezoelectric element 11. As a result, the direction of lateral displacement and the direction of ultrasonic generation are different directions, that is, the direction in which the electrodes of the piezoelectric element 11 are located and the direction in which ultrasonic waves are generated are different directions. Therefore, in the ultrasonic sensor 1 according to the second embodiment, an adhesive is applied between the piezoelectric body 111 and the acoustic matching layer 14 in the piezoelectric element 11, and it is possible to electrically connect the first metal thin film 15 to the first electrode 112 and electrically connect the second metal thin film 16 to the second electrode 113. In this ultrasonic sensor 1, by connecting the first wiring 12 to the first metal thin film 15, the first wiring 12 can be electrically connected to the first electrode 112 via the first metal thin film 15, and by connecting the second wiring 13 to the second metal thin film 16, it is possible to electrically connect the second wiring 13 to the second electrode 113 via the second metal thin film 16. Therefore, in the ultrasonic sensor 1 of embodiment 2, the metal plate 15b as in the conventional sensor is not necessary, and the number of adhesive layers using adhesive is reduced, making it possible to ensure long-term stability compared to the conventional sensor.

[0037] As described above, according to the second embodiment, there is provided a first metal thin film 15 provided on one surface of the acoustic matching layer 14 and electrically connected to the first electrode 112, and a second metal thin film 16 provided on one surface of the acoustic matching layer 14 and electrically connected to the second electrode 113, and the first wiring 12 is connected to the first metal thin film 15 by a conductive adhesive, and the second wiring 13 is connected to the second metal thin film 16 by a conductive adhesive. In the ultrasonic sensor 1 according to the second embodiment, for example, a piezoelectric element that performs lateral displacement or a piezoelectric element that performs sliding displacement is used as the piezoelectric element 11. As a result, the ultrasonic sensor 1 according to the second embodiment can be wired without using the metal plate 15b.

[0038] It should be noted that the embodiments may be freely combined, or any of the components in each embodiment may be modified, or any of the components in each embodiment may be omitted. [Explanation of symbols]

[0039] 1 Ultrasonic sensor 11 Piezoelectric element 12 First Wire 13 Second Wiring 14 Acoustic matching layer 15 First metal film 16 Second metal film 17 Adhesive 111 Piezoelectric 112 First electrode 113 Second Electrode 121 Solder 122 Conductive adhesive 131 Solder 132 Conductive adhesive

Claims

1. a piezoelectric element having a piezoelectric body, a first electrode provided on one surface of the piezoelectric body in one direction, and a second electrode provided on the other surface of the piezoelectric body in the one direction, and performing a displacement other than a longitudinal displacement; a first wiring electrically connected to the first electrode; a second wiring electrically connected to the second electrode; an acoustic matching layer having one surface connected to one surface of the piezoelectric element in a direction perpendicular to the one direction; An ultrasonic sensor comprising:

2. the first wiring is soldered to the first electrode; The second wiring is soldered to the second electrode.

2. The ultrasonic sensor according to claim 1.

3. a first metal thin film provided on one surface of the acoustic matching layer and electrically connected to the first electrode; a second metal thin film provided on one surface of the acoustic matching layer and electrically connected to the second electrode; the first wiring is connected to the first metal thin film by a conductive adhesive; The second wiring is connected to the second metal thin film by a conductive adhesive.

2. The ultrasonic sensor according to claim 1.

4. The piezoelectric element is a piezoelectric element that performs lateral displacement.

4. The ultrasonic sensor according to claim 1, wherein the ultrasonic sensor is a piezoelectric element.

5. The piezoelectric element is a piezoelectric element that performs a sliding displacement.

4. The ultrasonic sensor according to claim 1, wherein the ultrasonic sensor is a piezoelectric element.

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