TW202312666A - Ultrasonic transducer - Google Patents

Abstract

An ultrasonic transducer comprising a piezoceramic element, an acoustic matching layer, a stress balance layer and a damping layer. The stress-balance layer is connected to the piezoceramic element, and the stress-balance layer is harder than the damping layer, and its acoustic impedance is less than 5 MRayl.

Description

ultrasonic sensor

The present invention is an ultrasonic sensor in general, and more specifically, it relates to an ultrasonic sensor including a stress-balancing layer.

The ultrasonic transducer (ultrasonic transducer) can be used for short-distance object detection. It can calculate the difference between the ultrasonic sensor and the object to be detected by the time of flight (ToF) reflected back after the ultrasonic wave hits the object. distance between objects. For ultrasonic detection, the type and nature of the object to be detected are not subject to too many restrictions, including solids, liquids, or powders of various surface colors, transparency, hardness, etc., which can be used with ultrasonic sensors to detect. Therefore, ultrasonic sensors have been widely used in the fields of parking sensors, level sensors, multiple sheet detection and flow meters.

The main component of the ultrasonic sensor is piezoelectric ceramics (piezoceramics), such as ceramics made of lead zirconate titanate (PZT) material, which is coated with a conductive layer on both sides. Applying a high-frequency AC signal during operation will cause piezoelectric ceramics to generate high-frequency vibrations. The high-frequency vibrations are a type of sound wave. If the frequency of the sound wave falls within the ultrasonic range, it is ultrasonic vibration. In order to allow the generated ultrasonic waves to pass from the piezoelectric ceramics to the air, an acoustic resistance matching layer is set between the piezoelectric ceramics and the air, so that the acoustic resistances of the two can be matched, so that the ultrasonic waves can be effectively transmitted to the air. in the air. Generally, the matching layer material commonly used in the industry is a composite material mixed with polymer resin and hollow glass spheres to achieve lower acoustic resistance characteristics, and also has better weather resistance and reliability. However, the vibration generated by piezoelectric ceramics is transmitted toward the front (transmitter) and the back at the same time. If the ultrasonic waves emitted toward the back cannot be eliminated, there will be a large reverberation when using this ultrasonic sensor. The sound will make the signal discrimination invalid. Therefore, the damping layer becomes a necessary part of the ultrasonic sensor, which will be set around the piezoelectric ceramic and/or the acoustic resistance matching layer, so that the piezoelectric ceramic vibrates Aftermath can be quickly eliminated. For the shock absorber of ultrasonic sensors, the commonly used shock absorber material in the industry is a composite material mixed with polymer resin and metal or ceramic particles. Its acoustic impedance is closer to that of piezoelectric ceramics to absorb more back-transferred Ultrasonic, so that the aftershock of the ultrasonic sensor is reduced.

In order to let readers have a basic understanding of the aspects of this creation, the following paragraphs present a brief description of this creation. This summary is not an exhaustive overview of the content of the present invention, and it is not intended to indicate all key or essential elements of the present invention or to limit the scope of the present invention. Some of these concepts are presented in simplified form.

The purpose of the present invention is to propose a novel ultrasonic sensor, which is characterized in that a stress balance layer is added between the piezoelectric ceramics and the shock absorber to improve the piezoelectric ceramics and the acoustic resistance matching layer in high and low temperature environments. Due to the difference in thermal expansion coefficient, the acoustic resistance matching layer will generate thermal stress on the piezoelectric ceramic, which will cause the piezoelectric ceramic to crack. Secondly, the material of this stress balance layer is different from the shock absorber material with high density and high acoustic impedance commonly used in the industry. Its density is relatively low and the acoustic impedance is relatively low, so it can reduce the transmission of ultrasonic waves from the back of the piezoelectric ceramic. , thereby improving the emission sensitivity of the overall sensor. The ultrasonic sensor with the stress balance layer structure can improve the reliability of the ultrasonic sensor, and also provides the flexibility of the ultrasonic sensor in the shock-absorbing material configuration.

One aspect of the present invention is to provide an ultrasonic sensor, which includes a piezoelectric body, has a first surface and a second surface opposite to each other across the piezoelectric body, and a side connecting the first surface and the second surface surface. An acoustic resistance matching layer, the acoustic resistance matching layer has a third surface and a fourth surface facing each other through the acoustic resistance matching layer, and the third surface is in contact with the second surface of the piezoelectric body. A stress balance layer, the stress balance layer has a fifth surface and a sixth surface opposite to each other through the stress balance layer, and the sixth surface is in contact with the first surface of the piezoelectric body. The hardness of the stress balance layer is greater than that of the shock absorber, and the acoustic resistance of the stress balance layer is less than 5 MRayl. A shock absorber covers the stress balance layer, and/or the piezoelectric body, and/or the acoustic resistance matching layer.

Another aspect of the present invention is to provide an ultrasonic sensor, the stress balance layer of which has a through hole penetrating through the fifth surface and the sixth surface of the stress balance layer.

Another aspect of the present invention is to provide an ultrasonic sensor, the outer edge of the sixth surface of the stress balance layer can cover and extend forward to connect with the side surface of the piezoelectric body.

Another aspect of the present invention is to provide an ultrasonic sensor, which has a barrel-shaped carrier for accommodating a piezoelectric body, an acoustic resistance matching layer, a stress balancing layer, and a shock absorber.

Another aspect of the present invention is to provide an ultrasonic sensor, which has a tubular carrier for accommodating a piezoelectric body, an acoustic resistance matching layer, a stress balancing layer, and a shock absorber.

These and other objects of the present invention will surely become more apparent to the reader after reading the following detailed description of the preferred embodiment which is described in various figures and drawings.

In the following detailed description of the invention, reference numerals will be identified in the accompanying drawings which form a part therein, and are shown by way of description of specific examples in which the embodiment can be practiced. Such embodiments are shown in sufficient detail to enable one of ordinary skill in the art to implement them. For the sake of clarity, the dimensions of some elements in the illustrations may be exaggerated. Readers should understand that other embodiments may be used in the present invention or that structural, logical, and electrical changes may be made without departing from the described embodiments. Therefore, the following detailed description should not be regarded as a limitation; instead, the embodiments contained therein will be defined by the appended claims.

Please refer to FIG. 1 , which is a schematic cross-sectional structure diagram of an ultrasonic sensor according to a first embodiment of the present invention. As shown in FIG. 1 , the ultrasonic sensor 1 in this embodiment includes a piezoelectric body 10 , an acoustic impedance matching layer 20 , a stress balancing layer 30 and a shock absorber 40 . Wherein the piezoelectric body 10 is located between the acoustic resistance matching layer 20 and the stress balancing layer 30, and the shock absorber 40 covers the stress balancing layer 30, and/or covers the piezoelectric body 10, and/or covers the acoustic resistance matching Layer 20.

In more detail, in this embodiment, the piezoelectric body 10 has a first surface 10A, and a second surface 10B opposite to the first surface 10A through the piezoelectric body 10 , and has a second surface connecting the first surface 10A and the second surface 10A. The side surface 10C and the side surface 10D of the surface 10B. The acoustic resistance matching layer 20 has a third surface 20A, and a fourth surface 20B opposite to the third surface 20A via the acoustic resistance matching layer 20 , and the third surface 20A of the acoustic resistance matching layer 20 and the piezoelectric body 10 The second surfaces 10B are in contact. The stress balance layer 30 has a fifth surface 30A, and a sixth surface 30B opposite to the fifth surface 30A via the stress balance layer 30 , wherein the sixth surface 30B of the stress balance layer 30 is connected to the first surface of the piezoelectric body 10 10A connected. In addition, the shock absorber 40 is in contact with the fifth surface 30A of the stress balance layer 30, and covers the side wall of the stress balance layer 30. In addition, in this embodiment, the shock absorber 40 also covers the side wall of the piezoelectric body 10, and It partially covers the sidewall of the acoustic resistance matching layer 20 . However, it is worth noting that the covering range of the shock absorbing body 40 may be adjusted according to actual needs, that is to say, in other embodiments of the present invention, the shock absorbing body 40 may cover more/or fewer layers of surfaces Or the sidewall, the present invention is not limited thereto.

In this embodiment, the piezoelectric body 10 is made of piezoelectric ceramics, such as barium titanate (BaTiO ₃ ), lead titanate (PbTiO ₃ ), lead zirconate titanate (Pb(ZrTi)O ₃ , PZT), etc. But not limited to this. The material of the acoustic resistance matching layer 20 includes an organic polymer material or a composite material mixed with an organic polymer material and a hollow powder or a solid powder. For example, the organic polymer material includes epoxy resin (epoxy), vinyl ester Resin (vinyl ester resin), ultraviolet curing glue (UV glue), polyurethane (polyurethane), acrylic resin (acrylic resin), or cyanate ester resin (cyanate ester resin), but not limited thereto. The material of the stress balance layer 30 includes an organic polymer material or a composite material mixed with an organic polymer material and hollow powder or solid powder. For example, the organic polymer material includes epoxy resin (epoxy), vinyl ester resin (vinyl ester resin), ultraviolet curing glue (UV glue), polyurethane (polyurethane), acrylic resin (acrylic resin), or cyanate ester resin (cyanate ester resin), but not limited thereto. The material of the shock absorber 40 includes an organic polymer material or a composite material mixed with an organic polymer material and metal or ceramic particles. The organic polymer material includes epoxy resin (epoxy), polyurethane (polyurethane), Or silicone (silicone), but not limited to this.

In this embodiment, the function of the piezoelectric body 10 is to generate ultrasonic waves through high-frequency vibrations, because the acoustic resistance of the piezoelectric body 10 (about 35 MRayl, about 35*10 ⁶ kg/square meter∙s) and the air Acoustic resistance (approximately 4*10 ^-4 MRayl), the difference in acoustic resistance between the two is 5 series, so it is necessary to set the acoustic resistance matching layer 20 between the piezoelectric body 10 and the air, so that the piezoelectric body 10 and the air Acoustic resistance is matched to efficiently transmit ultrasound waves into the air. In addition, the purpose of setting the shock absorber 40 is to reduce the reverberation generated when the ultrasonic sensor is used. The piezoelectric body 10 , the acoustic resistance matching layer 20 and the shock absorber 40 are all common components of conventional ultrasonic sensors, and their detailed principles and materials belong to the known technology in the art, and will not be repeated here.

However, there is a defect in the conventional ultrasonic sensor, that is, the acoustic resistance matching layer of the conventional ultrasonic sensor is only located on one side surface of the piezoelectric body, so it is easy to fail under the temperature cycle test due to the thermal expansion coefficient of the piezoelectric body. The thermal expansion coefficient difference with the acoustic resistance matching layer is large, resulting in cracking. In more detail, general ultrasonic sensors usually go through a temperature cycle test (such as a cycle test at minus 40 degrees Celsius to plus 85 degrees Celsius) before leaving the factory to test the performance of the ultrasonic sensor under environmental temperature changes. reliability. The applicant found that in the conventional ultrasonic sensor (that is, an ultrasonic sensor that only includes a piezoelectric body, an acoustic resistance matching layer, and a shock absorber), since the acoustic resistance matching layer is only located on one side of the piezoelectric body, and the The thermal expansion coefficient of the upper piezoelectric body and the acoustic resistance matching layer is quite different (generally speaking, the thermal expansion coefficient of the piezoelectric body is about 5PPM, while the thermal expansion coefficient of the acoustic resistance matching layer is about 50PPM, and the difference between the two is nearly 10 times), so in During the temperature cycle test, the one-sided surface of the piezoelectric body, that is, the surface adjacent to the acoustic resistance matching layer, is susceptible to significant compression/stretch force, which in turn causes the piezoelectric body to break.

The reason for the fragmentation of the piezoelectric body above is mainly due to the fact that the acoustic resistance matching layer is only provided on one surface of the piezoelectric body, while the other surface of the piezoelectric body is directly connected to the shock absorber, so when thermal expansion and contraction occur , the piezoelectric body is subjected to relatively obvious stress from one side (that is, the acoustic resistance matching layer), and then cracks. Therefore, the present embodiment is characterized in that a stress balancing layer 30 is additionally provided on the other surface of the piezoelectric body 10 (that is, the surface opposite to the acoustic resistance matching layer 20 ). In some embodiments, the material of the stress balancing layer 30 can be the same as that of the acoustic resistance matching layer 20, and the stress balancing layer 30 and the acoustic resistance matching layer 20 are respectively arranged on both sides of the piezoelectric body 10, so when performing the temperature cycle test Therefore, the stress borne by the piezoelectric body 10 will be evenly distributed to both sides to achieve the effect of stress balance on both sides, and it is not easy for the piezoelectric body 10 to bear the stress from a single side and cause cracking.

It should be noted that in the present invention, the stress balance layer 30 and the shock absorber 40 belong to different layers, and the two preferably contain different materials, because the material and application of the shock absorber 40 are different from the stress balance layer 30, so In the present invention, preferably, all or part of the shock absorber 40 is not used as the stress balance layer 30 instead. In this embodiment, the hardness of the stress balance layer 30 is greater than that of the shock absorber 40, and the acoustic resistance of the stress balance layer 30 is less than 5 MRayl. In the present invention, the stress balance layer 30 is added between the piezoelectric body 10 and the shock absorber 40, which can effectively improve the reliability and durability of the ultrasonic sensor compared with the conventional technology (that is, the structure without the stress balance layer) sex. According to the applicant's actual test results, the conventional ultrasonic sensor may break the piezoelectric body after about 10 temperature cycle tests. However, after the stress balancing layer 30 is added in the present invention, the ultrasonic sensor 1 It can not be broken after more than 50 temperature cycle tests, so the reliability of the ultrasonic sensor is greatly improved.

In addition, in addition to the advantage of improving reliability, the ultrasonic sensor of the present invention can also adjust the parameters of the stress balance layer 30, such as adjusting the thickness or material, so as to reduce the transmission efficiency of the ultrasonic wave generated by the piezoelectric body 10 from the back , and then improve the front emission efficiency of the ultrasonic sensor 1 .

The following description will focus on different implementations of the ultrasonic sensor of the present invention, and to simplify the description, the following description will mainly focus on the differences between the embodiments, and will not repeat the similarities. In addition, the same elements in the various embodiments of the present invention are marked with the same reference numerals to facilitate mutual comparison between the various embodiments.

FIG. 2 is a schematic cross-sectional structure diagram of an ultrasonic sensor according to a second embodiment of the present invention. As shown in Figure 2, the ultrasonic sensor of this embodiment is similar to the ultrasonic sensor (see Figure 1) described in the first embodiment above, and the main difference is that the ultrasonic sensor 2 in this embodiment The stress balance layer 30 further includes a plurality of through holes 32 , wherein the through holes 32 are hollow hole structures penetrating through the fifth surface 30A and the sixth surface 30B of the stress balance layer 30 . Viewed from its section, its shape includes, but is not limited to, circular, rectangular, triangular, irregular or other shapes. In this embodiment, the through holes 32 have the effect of reducing the overall density of the stress balance layer 30 to achieve low acoustic resistance, thereby improving the sensitivity of ultrasonic waves emitted from the front acoustic resistance matching layer. Except for the above features, the material properties or structures of other components in this embodiment are the same as those described in the first embodiment above, and will not be repeated here.

FIG. 3 is a schematic cross-sectional structure diagram of an ultrasonic sensor according to a third embodiment of the present invention. As shown in Fig. 3, the ultrasonic sensor of this embodiment is similar to the ultrasonic sensor (see Fig. 1) described in the first embodiment above, and the main difference is that the ultrasonic sensor 3 in this embodiment The stress balancing layer 30 not only covers the first surface 10A of the piezoelectric body 10 , but also partially extends to cover the side surfaces 10C, 10D of the piezoelectric body 10 . That is to say, the outer edge of the sixth surface 30B of the stress balancing layer 30 can cover and extend forward to connect with the side surfaces 10C and 10D of the piezoelectric body 10 . In this way, the piezoelectric body 10 can be protected more effectively, and the sidewall of the piezoelectric body 10 is not easily broken. Except for the above features, the material properties or structures of other components in this embodiment are the same as those described in the first embodiment above, and will not be repeated here.

FIG. 4 is a schematic cross-sectional structure diagram of an ultrasonic sensor according to a fourth embodiment of the present invention. As shown in Fig. 4, the ultrasonic sensor 4 of the present embodiment is similar to the ultrasonic sensor (see Fig. 1) described in the above-mentioned first embodiment, and the main difference is that the ultrasonic sensor 4 in the present embodiment is more It includes a barrel-shaped carrier 50 , wherein the above-mentioned piezoelectric body 10 , acoustic resistance matching layer 20 , stress balance layer 30 and shock absorber 40 are located in the barrel-shaped carrier 50 . In more detail, the barrel-shaped carrier 50 has a barrel bottom 51 and a barrel body 52, and the barrel-shaped carrier 50 has a seventh surface 50A and an eighth surface 50B opposite to each other across the barrel bottom 51, wherein the piezoelectric body 10, The acoustic resistance matching layer 20 , the stress balancing layer 30 and the shock absorber 40 are disposed in the barrel-shaped carrier 50 , and the seventh surface 50A of the barrel bottom 51 of the barrel-shaped carrier 50 and the fourth surface 20B of the acoustic resistance matching layer 20 connect. The barrel-shaped carrier 50 can be used as a casing of the ultrasonic sensor 4 to protect other internal components. Wherein, the material of the barrel-shaped carrier 50 may include metal, plastic, polymer material, etc., but is not limited thereto. Except for the above features, the material properties or structures of other components in this embodiment are the same as those described in the first embodiment above, and will not be repeated here.

FIG. 5 is a schematic cross-sectional structure diagram of an ultrasonic sensor according to a fifth embodiment of the present invention. As shown in Fig. 5, the ultrasonic sensor 5 of the present embodiment is similar to the ultrasonic sensor (see Fig. 1) described in the above-mentioned first embodiment, and the main difference is that the ultrasonic sensor 5 in the present embodiment is more It includes a tubular carrier 60 , wherein the piezoelectric body 10 , the acoustic resistance matching layer 20 , the stress balance layer 30 and the shock absorber 40 are located in the tubular carrier 60 . In more detail, the tubular carrier 60 has an inner surface 61 and an outer surface 62 opposite to each other across the tubular carrier 60, and a first opening 63 and a second opening 64 opposite to each other, and the shock absorber 40 covers the piezoelectric body 10 and the second opening 64. The stress balance layer 30, wherein the inner surface 61 of the tubular carrier 60 surrounds the shock absorber 40 and is in contact with the shock absorber 40, and the fourth surface 20B of the acoustic resistance matching layer 20 is exposed from the first opening 63 of the tubular carrier 60 . The tubular carrier 60 can also protect other internal components. In addition, the tubular carrier 60 can easily control the emission direction of the ultrasonic waves. Except for the above features, the material properties or structures of other components in this embodiment are the same as those described in the first embodiment above, and will not be repeated here.

In addition to the barrel-shaped carrier or the tubular carrier mentioned above, in some embodiments, other shapes of carriers, such as plate-shaped carriers, may also be included. In some other embodiments, a plate-shaped carrier may be used instead of the acoustic resistance matching layer. FIG. 6 is a schematic cross-sectional structure diagram of an ultrasonic sensor according to a sixth embodiment of the present invention. As shown in Figure 6. The ultrasonic sensor 6 of this embodiment is similar to the ultrasonic sensor described in the first embodiment above (please see Fig. 1), and also includes a piezoelectric body 10, a stress balancing layer 30 and a shock absorber 40 in this embodiment . However, in this embodiment, the acoustic resistance matching layer 20 in the above-mentioned first embodiment is replaced by the carrier 70 . In more detail, this embodiment includes: a piezoelectric body 10, having a first surface 10A and a second surface 10B facing each other through the piezoelectric body 10, and a side connecting the first surface 10A and the second surface 10B Surface 10C, side surface 10D; a carrier 70, the carrier 70 has a third surface 70A and a fourth surface 70B facing each other across the carrier 70, and the third surface 70A is in contact with the second surface 10B of the piezoelectric body 10 A stress balance layer 30, the stress balance layer 30 has a fifth surface 30A and a sixth surface 30B opposite to each other across the stress balance layer 30, the sixth surface 30B is in contact with the first surface 10A of the piezoelectric body 10, and the stress balance The acoustic resistance of the layer is less than 5 MRayl; and a shock absorber 40, covering the stress balance layer 30, and/or the piezoelectric body 10, and/or the carrier 70, and the hardness of the stress balance layer 30 is greater than that of the shock absorber 40 hardness. In this embodiment, the carrier 70 is used as the acoustic resistance matching layer in the original first embodiment, which can save part of the component space and simplify the manufacturing process. Among them, the carrier 70 can also be made of materials similar to the acoustic resistance matching layer, such as organic polymer materials or composite materials mixed with organic polymer materials and hollow powders or solid powders. The organic polymer materials include Epoxy, vinyl ester resin, UV glue, polyurethane, acrylic resin, or cyanate ester resin , but not limited to this. Except for the above features, the material properties or structures of other components in this embodiment are the same as those described in the first embodiment above, and will not be repeated here.

Figure 7 shows a schematic cross-sectional structure of an ultrasonic sensor according to a seventh embodiment of the present invention, Figure 8 shows a schematic cross-sectional structure of an ultrasonic sensor according to an eighth embodiment of the present invention, and Figure 9 shows a schematic cross-sectional structure of an ultrasonic sensor according to an eighth embodiment of the present invention Schematic diagram of the cross-sectional structure of the ultrasonic sensor of the ninth embodiment. In these embodiments, the concept of replacing the acoustic resistance matching layer with a carrier in the sixth embodiment above can be applied here. As shown in Fig. 7, the ultrasonic sensor 7 described in the seventh embodiment is similar to the ultrasonic sensor described in the second embodiment (please see Fig. 2), the difference is that the ultrasonic sensor 7 does not include an acoustic sensor in this embodiment. Instead of the resistance matching layer, the carrier 70 is used instead of the acoustic resistance matching layer. The material and characteristics of the carrier 70 have been described in the above-mentioned embodiments, and will not be repeated here. Except for the above features, the material properties or structures of other components in this embodiment are the same as those described in the above embodiments, and will not be repeated here.

Likewise, as shown in Fig. 8, the ultrasonic sensor 8 described in the eighth embodiment is similar to the ultrasonic sensor (see Fig. 3) described in the third embodiment, the difference is that the ultrasonic sensor 8 in this embodiment The acoustic resistance matching layer is not included, but the carrier 70 is used instead of the acoustic resistance matching layer. The material and characteristics of the carrier 70 have been described in the above-mentioned embodiments, and will not be repeated here. Except for the above features, the material properties or structures of other components in this embodiment are the same as those described in the above embodiments, and will not be repeated here.

In the same way, as shown in Figure 9, the ultrasonic sensor 9 described in the ninth embodiment is similar to the ultrasonic sensor described in the fourth embodiment (please see Figure 4), the difference is that the ultrasonic sensor 9 in this embodiment The acoustic resistance matching layer is not included, but the barrel-shaped carrier 50 is used instead of the acoustic resistance matching layer. The material and characteristics of the barrel-shaped carrier 50 have been described in the above-mentioned embodiments, and will not be repeated here. Except for the above features, the material properties or structures of other components in this embodiment are the same as those described in the above embodiments, and will not be repeated here.

FIG. 10 is a schematic cross-sectional structure diagram of an ultrasonic sensor according to a tenth embodiment of the present invention. In this embodiment, the structure of the ultrasonic sensor 10 is similar to the structure of the ultrasonic sensor 4 described in the fourth embodiment, but the difference is that the acoustic resistance matching layer 20 is arranged outside the barrel-shaped carrier 50 in this embodiment, That is to say, the third surface 20A of the acoustic resistance matching layer 20 is connected to the eighth surface 50B of the barrel-shaped carrier 50 . Except for the above features, the material properties or structures of other components in this embodiment are the same as those described in the above embodiments, and will not be repeated here.

In summary, the purpose of the present invention is to propose a novel ultrasonic sensor, which is characterized in that a stress balance layer is added between the piezoelectric ceramic and the shock absorber to improve the resistance between the piezoelectric ceramic and the acoustic resistance matching layer at high pressure. In a low-temperature environment, due to the difference in thermal expansion coefficient, the acoustic resistance matching layer will generate thermal stress on the piezoelectric ceramic, which will cause the piezoelectric ceramic to crack. Secondly, the material of this stress balance layer is different from the shock absorber material with high density and high acoustic impedance commonly used in the industry. Its density is relatively low and the acoustic impedance is relatively low, so it can reduce the transmission of ultrasonic waves from the back of the piezoelectric ceramic. , thereby improving the emission sensitivity of the overall sensor. The ultrasonic sensor with the stress balance layer structure can improve the reliability of the ultrasonic sensor, and also provides the flexibility of the ultrasonic sensor in the shock-absorbing material configuration. The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10: Ultrasonic sensor 10: Piezoelectric body 10A: first surface 10B: second surface 10C: side surface 10D: side surface 20: Acoustic resistance matching layer 20A: third surface 20B: fourth surface 30: Stress balance layer 30A: fifth surface 30B: sixth surface 32: through hole 40: shock absorber 50: Barrel carrier 50A: seventh surface 50B: eighth surface 51: barrel bottom 52: Barrel body 60: Tubular carrier 61: inner surface 62: Outer surface 63: First opening 64: second opening 70: Carrier 70A: third surface 70B: fourth surface

This specification contains drawings and constitutes a part of this specification, so that readers can have a further understanding of the embodiments of the present invention. The drawings depict some embodiments of the invention and together with the description herein explain the principles thereof. In these illustrations: Figure 1 shows a schematic cross-sectional structure diagram of an ultrasonic sensor according to a first embodiment of the present invention; Fig. 2 shows a schematic cross-sectional structure diagram of an ultrasonic sensor according to a second embodiment of the present invention; Fig. 3 shows a schematic cross-sectional structure diagram of an ultrasonic sensor according to a third embodiment of the present invention; Fig. 4 shows a schematic cross-sectional structure diagram of an ultrasonic sensor according to a fourth embodiment of the present invention; Fig. 5 shows a schematic cross-sectional structure diagram of an ultrasonic sensor according to a fifth embodiment of the present invention; Fig. 6 shows a schematic cross-sectional structure diagram of an ultrasonic sensor according to a sixth embodiment of the present invention; Fig. 7 shows a schematic cross-sectional structure diagram of an ultrasonic sensor according to a seventh embodiment of the present invention; Fig. 8 shows a schematic cross-sectional structure diagram of an ultrasonic sensor according to an eighth embodiment of the present invention; Fig. 9 shows a schematic cross-sectional structure diagram of an ultrasonic sensor according to a ninth embodiment of the present invention; and FIG. 10 is a schematic cross-sectional structure diagram of an ultrasonic sensor according to a tenth embodiment of the present invention.

1: Ultrasonic sensor

10: Piezoelectric body

10A: first surface

10B: second surface

10C: side surface

10D: side surface

20: Acoustic resistance matching layer

20A: third surface

20B: fourth surface

30: Stress balance layer

30A: fifth surface

30B: sixth surface

40: shock absorber

Claims (17)

An ultrasonic sensor comprising: A piezoelectric body, having a first surface and a second surface facing each other across the piezoelectric body, and a side surface connecting the first surface and the second surface; an acoustic resistance matching layer, the acoustic resistance matching layer has a third surface and a fourth surface opposite to each other through the acoustic resistance matching layer, and the third surface is in contact with the second surface of the piezoelectric body; A stress balance layer, the stress balance layer has a fifth surface and a sixth surface opposite to each other across the stress balance layer, the sixth surface is in contact with the first surface of the piezoelectric body, and the acoustic resistance of the stress balance layer is less than 5 MRayl; and A shock absorbing body covers the stress balancing layer, and/or the piezoelectric body, and/or the acoustic resistance matching layer, wherein the hardness of the stress balancing layer is greater than that of the shock absorbing body. The ultrasonic sensor described in Item 1 of the scope of patent application, wherein the stress balance layer further includes organic polymer materials or composite materials mixed with organic polymer materials and hollow powders or solid powders, the organic polymer materials Molecular materials include epoxy resin (epoxy), vinyl ester resin (vinyl ester resin), ultraviolet curing glue (UV glue), polyurethane (polyurethane), acrylic resin (acrylic resin), or cyanate resin (cyanate) ester resin). The ultrasonic sensor as described in item 1 of the scope of the patent application, wherein the stress balance layer has a through hole penetrating through the fifth surface and the sixth surface of the stress balance layer. According to the ultrasonic sensor described in item 1 of the patent application scope, the outer edge of the sixth surface of the stress balance layer can cover and extend forward to connect with the side surface of the piezoelectric body. The ultrasonic sensor as described in item 1 of the scope of patent application further comprises a barrel-shaped carrier with a barrel bottom and a barrel body, and the barrel-shaped carrier has a seventh surface and an eighth surface opposite to each other across the barrel bottom. Surface, wherein the piezoelectric body, the acoustic resistance matching layer, the stress balance layer and the shock absorber are arranged in the barrel-shaped carrier, and the seventh surface of the barrel bottom of the barrel-shaped carrier and the acoustic resistance The fourth surfaces of the matching layer are in contact. The ultrasonic sensor as described in item 1 of the scope of patent application further includes a tubular carrier, with opposite inner and outer surfaces and opposite first and second openings across the tubular carrier, and a shock absorber The body wraps the piezoelectric body and the stress balance layer, wherein the inner surface of the tubular carrier surrounds the shock absorber and is in contact with the shock absorber, and the fourth surface of the acoustic resistance matching layer is separated from the tubular The first opening of the carrier is exposed. The ultrasonic sensor as described in Item 1 of the scope of the patent application, wherein the shock absorber contains organic polymer materials or composite materials mixed with organic polymer materials and metal or ceramic particles, and the organic polymer materials include rings epoxy, polyurethane, or silicone. The ultrasonic sensor described in item 1 of the scope of the patent application, wherein the acoustic resistance matching layer contains organic polymer materials or composite materials made of organic polymer materials mixed with hollow powder or solid powder, the organic high polymer Molecular materials include epoxy resin (epoxy), vinyl ester resin (vinyl ester resin), ultraviolet curing glue (UV glue), polyurethane (polyurethane), acrylic resin (acrylic resin), or cyanate resin (cyanate) ester resin). An ultrasonic sensor comprising: A piezoelectric body, having a first surface and a second surface facing each other across the piezoelectric body, and a side surface connecting the first surface and the second surface; a carrier, the carrier has a third surface and a fourth surface opposite to each other across the carrier, and the third surface is in contact with the second surface of the piezoelectric body; A stress balance layer, the stress balance layer has a fifth surface and a sixth surface opposite to each other across the stress balance layer, the sixth surface is in contact with the first surface of the piezoelectric body, and the acoustic resistance of the stress balance layer is less than 5 MRayl; and A shock absorber covers the stress balance layer, and/or the piezoelectric body, and/or the bearing body, and the hardness of the stress balance layer is greater than that of the shock absorber. The ultrasonic sensor as described in item 9 of the scope of patent application, wherein the stress balance layer further includes organic polymer materials or composite materials mixed with organic polymer materials and hollow powders or solid powders, the organic polymer materials Molecular materials include epoxy resin (epoxy), vinyl ester resin (vinyl ester resin), ultraviolet curing glue (UV glue), polyurethane (polyurethane), acrylic resin (acrylic resin), or cyanate resin (cyanate) ester resin). The ultrasonic sensor as described in claim 9 of the patent application, wherein the stress balance layer has a through hole penetrating through the fifth surface and the sixth surface of the stress balance layer. The ultrasonic sensor as described in item 9 of the patent application scope, wherein the outer edge of the sixth surface of the stress balance layer can cover and extend forward to connect with the side surface of the piezoelectric body. The ultrasonic sensor as described in item 9 of the scope of patent application, wherein the carrier further includes a barrel-shaped carrier with a barrel bottom and a barrel body, and the barrel-shaped carrier has a third opposite across the barrel bottom. surface and the fourth surface, wherein the piezoelectric body, the stress balance layer and the shock absorber are arranged in the barrel of the barrel-shaped carrier, and the third surface of the bottom of the barrel of the barrel-shaped carrier and the pressure The second surface of the electric body is in contact with each other. The ultrasonic sensor as described in item 9 of the scope of patent application, wherein the material of the carrier includes metal materials selected from the following groups or combinations thereof: aluminum, titanium, copper, stainless steel, or the following groups or combinations thereof Non-metallic materials: glass, acrylic, Teflon (PTFE), polyvinyl difluoride (PVDF), polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), polyethylene terephthalic acid Butyl ester (PBT), acrylonitrile-butadiene-styrene copolymer (ABS), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), or polyether ether ketone (PEEK). The ultrasonic sensor as described in item 9 of the scope of patent application, wherein the shock absorber includes organic polymer materials or composite materials mixed with organic polymer materials and metal or ceramic particles, and the organic polymer materials include rings epoxy, polyurethane, or silicone. The ultrasonic sensor as described in claim 9 of the patent application further includes an acoustic resistance matching layer, and the acoustic resistance matching layer is in contact with the fourth surface of the carrier. The acoustic resistance matching layer described in item 16 of the scope of the patent application includes an organic polymer material or a composite material mixed with an organic polymer material and hollow powder or solid powder. The organic polymer material includes epoxy Epoxy, vinyl ester resin, UV glue, polyurethane, acrylic resin, or cyanate ester resin.

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