WO2023071107A1 - 超声换能器及电子设备 - Google Patents

超声换能器及电子设备 Download PDF

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Publication number
WO2023071107A1
WO2023071107A1 PCT/CN2022/089833 CN2022089833W WO2023071107A1 WO 2023071107 A1 WO2023071107 A1 WO 2023071107A1 CN 2022089833 W CN2022089833 W CN 2022089833W WO 2023071107 A1 WO2023071107 A1 WO 2023071107A1
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Prior art keywords
ultrasonic transducer
film
film layer
layer
sound outlet
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PCT/CN2022/089833
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English (en)
French (fr)
Inventor
朱博通
许光耀
陈才
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广州视源电子科技股份有限公司
广州视源人工智能创新研究院有限公司
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Publication of WO2023071107A1 publication Critical patent/WO2023071107A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
    • G01S15/02—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems using reflection of acoustic waves
    • G01S15/06—Systems determining the position data of a target
    • G01S15/08—Systems for measuring distance only
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
    • G01S7/521—Constructional features

Definitions

  • the present application relates to waterproof membrane technology, for example, to an ultrasonic transducer and electronic equipment.
  • the ultrasonic radar calculates the distance from the ultrasonic radar to the target surface through the sending and receiving time of the ultrasonic signal.
  • Ultrasonic radar has been widely used in automatic parking systems.
  • the waterproof method adopted by the ultrasonic transducer in the related art causes a large loss of sensitivity of the ultrasonic transducer.
  • the application provides an ultrasonic transducer and electronic equipment, which improves the sensitivity of the ultrasonic transducer.
  • the present application provides an ultrasonic transducer, including a protective shell, a piezoelectric film and a film layer;
  • the protective shell has a sound outlet communicating with the accommodation cavity, and the sound outlet is opposite to the piezoelectric film;
  • the film layer covers the sound outlet, and the resonant frequency of the film layer is the same as the working frequency of the ultrasonic transducer.
  • the membrane layer is located in the accommodation cavity, and the membrane layer is connected to the inner wall of the accommodation cavity;
  • the film layer is located on the protective shell, and the film layer is connected to the outer wall of the protective shell.
  • the film layer is bonded to the inner wall of the accommodation cavity
  • the film layer is bonded to the outer wall of the protective shell.
  • the sound outlet is a round hole.
  • the film layer is a waterproof film
  • the film layer is a thermoplastic polyester layer.
  • the film layer has pores, and the diameter of the pores is 0.4 ⁇ m-0.44 ⁇ m.
  • the thickness of the film layer is calculated by Formula 1 and Formula 2;
  • f tp is the resonant frequency of the membrane layer in formula 1
  • K n is a constant
  • the value of K n is 10.22
  • ⁇ is the density of the membrane layer
  • d m is the thickness of the membrane layer
  • R is the radius of the sound outlet
  • D E is the bending stiffness of the film
  • E is the equivalent Young's modulus of the film
  • d m is the thickness of the film
  • ⁇ is the Poisson's ratio of the film.
  • the protective case includes a base and a cover covering the base, the base and the cover together form an accommodation cavity, and the sound outlet is located on the base.
  • the ultrasonic transducer provided by the present application further includes a circuit board and a chip;
  • the piezoelectric film and the chip are electrically connected to the circuit board;
  • the circuit board is attached to the base
  • the piezoelectric film and chip are covered with an encapsulation layer.
  • the present application provides an electronic device, including an electronic device body and the ultrasonic transducer provided in the above first aspect connected to the electronic device body.
  • the ultrasonic transducer is provided with a protective shell, a piezoelectric film and a film layer, the protective shell has an accommodation cavity, and the protective shell has a sound outlet connected to the accommodation cavity.
  • the film is located in the housing cavity, the sound outlet is opposite to the piezoelectric film, the film layer covers the sound outlet, and the resonant frequency of the film layer is the same as the working frequency of the ultrasonic transducer, so that the ultrasonic waves generated by the piezoelectric film pass through the sound outlet. Mouth and membranous efferent.
  • the membrane layer is used to protect the ultrasonic transducer from water or dust.
  • the resonant frequency of the membrane layer is the same as the working frequency of the ultrasonic transducer, thereby improving the sound transmission performance of the membrane layer and reducing the generation of ultrasonic waves when passing through the membrane layer.
  • the loss of the ultrasonic transducer avoids the decrease of the detection distance.
  • FIG. 1 is a schematic structural diagram of an ultrasonic transducer provided in an embodiment of the present application
  • Fig. 2 is a schematic diagram of the connection position of the film layer in the ultrasonic transducer provided by the embodiment of the present application;
  • FIG. 3 is a schematic structural view of the film layer in the ultrasonic transducer provided by the embodiment of the present application;
  • FIG. 4 is a schematic structural diagram of a support frame in an ultrasonic transducer provided in an embodiment of the present application
  • Fig. 5 is another schematic structural view of the support frame in the ultrasonic transducer provided by the embodiment of the present application.
  • connection should be understood in a broad sense, for example, it can be a fixed connection or an intermediate connection.
  • the media is indirectly connected, which can be the internal communication of two elements or the interaction relationship between two elements.
  • the ultrasonic radar calculates the distance from the ultrasonic radar to the target surface through the sending and receiving time of the ultrasonic signal.
  • Ultrasonic radar has been widely used in automatic parking systems. With the trend of miniaturization of consumer electronics products becoming more and more obvious, several companies have introduced a piezoelectric film-based ultrasonic transducer to replace the traditional vehicle-mounted ultrasonic radar. This ultrasonic transducer has been used in AR/VR, electronic door locks and sweeping robots. Ultrasound transducers are not waterproof, which greatly limits their usefulness. In order to realize waterproofing of the ultrasonic transducer, a waterproof film is usually arranged on the ultrasonic transducer to protect the ultrasonic transducer. However, the waterproof membrane provided in the related art has poor sound transmission performance, which causes relatively large losses in the ultrasonic wave propagation process.
  • the application provides an ultrasonic transducer and electronic equipment.
  • the ultrasonic transducer is protected by setting a film layer at the sound outlet of the ultrasonic transducer.
  • the resonant frequency of the film layer is the same as that of the ultrasonic transducer. In this way, the sound transmission performance of the membrane layer can be improved, and the loss of the ultrasonic wave passing through the membrane layer can be reduced, thereby avoiding the decrease of the detection distance of the ultrasonic transducer.
  • Fig. 1 is a schematic structural diagram of the ultrasonic transducer provided by the embodiment of the present application.
  • the ultrasonic transducer 1 provided by the present application includes a protective shell 11, a piezoelectric film 12 and a film layer 13, and the protective shell 11 There is an accommodating cavity 14 inside, and the piezoelectric film 12 is located in the accommodating cavity 14 .
  • the protective shell 11 has a sound outlet 111 communicating with the accommodation cavity 14 , and the sound outlet 111 is opposite to the piezoelectric film 12 .
  • the membrane layer 13 covers the sound outlet 111 , and the resonant frequency of the membrane layer 13 is the same as the working frequency of the ultrasonic transducer 1 .
  • the membrane layer 13 may be a dustproof membrane or a waterproof membrane.
  • the arrangement of the film layer 13 can effectively protect the ultrasonic transducer 1, preventing particulate matter such as dust, sand, or liquids such as water and oil from entering the accommodation cavity 14 through the sound outlet 111, thereby preventing the ultrasonic transducer The working performance of the energy device 1 will be affected.
  • the edge of the piezoelectric film 12 is fixed in the accommodating cavity 14, and the middle position is suspended.
  • the piezoelectric film 12 vibrates through the forward and reverse piezoelectric effects of the piezoelectric material, so as to transmit or receive ultrasonic signals.
  • the piezoelectric film 12 can be used not only as an actuator (emitting sound waves), but also as a sensor (receiving sound waves).
  • the piezoelectric material used for the piezoelectric film 12 may be aluminum nitride (AlN) or lead zirconate titanate (PZT).
  • the protective shell 11 may be a metal shell or a plastic shell, and the protective shell 11 is used to protect the components in the accommodating cavity 14 to prevent the internal components from being impacted by collisions.
  • the resonant frequency of the film layer 13 is the same as the working frequency of the ultrasonic transducer 1 , for example, the working frequency of the ultrasonic transducer 1 is 80 kHz.
  • the membrane layer 13 When the membrane layer 13 resonates with the ultrasonic transducer 1 , that is, when the resonance frequency of the membrane layer 13 is 80 kHz, the acoustic impedance of the membrane layer 13 reaches a minimum value. In this way, the sound transmission performance of the membrane layer 13 can be improved, so that no loss occurs when the ultrasonic wave passes through the membrane layer 13 , thereby avoiding a decrease in the detection distance of the ultrasonic transducer 1 .
  • the processing system calculates the time when the piezoelectric film 12 sends and receives the ultrasonic signal, and multiplies the time by the speed of sound to obtain the distance from the ultrasonic transducer 1 to the target.
  • the ultrasonic transducer 1 provided in this embodiment is provided with a protective shell 11, a piezoelectric film 12 and a film layer 13.
  • the protective shell 11 has an accommodation cavity 14, and the protective shell 11 has a sound outlet 111 communicating with the accommodation cavity 14.
  • the piezoelectric film 12 is located in the housing cavity 14, the sound outlet 111 is opposite to the piezoelectric film 12, the film layer 13 covers the sound outlet 111, and the resonant frequency of the film layer 13 is the same as the working frequency of the ultrasonic transducer 1 , so that the ultrasonic wave generated by the piezoelectric film 12 is transmitted through the sound outlet 111 and the film layer 13 .
  • membrane layer 13 to carry out waterproof or dustproof protection to ultrasonic transducer 1
  • the resonant frequency of membrane layer 13 is identical with the working frequency of ultrasonic transducer 1, thus improved the sound permeability of membrane layer 13, thereby reduced
  • the loss generated when the ultrasonic wave passes through the membrane layer 13 avoids the decrease of the detection distance of the ultrasonic transducer 1 .
  • the membrane layer 13 is located in the housing chamber 14, and the membrane layer 13 is connected to the inner wall of the housing chamber 14 in the protective case 11, so that the membrane layer 13 can be Installed in the ultrasonic transducer 1 , the protective shell 11 protects the film layer 13 so that the film layer 13 is not easily separated from the protective shell 11 , thereby improving the service life of the film layer 13 .
  • FIG 2 is a schematic diagram of the connection position of the film layer in the ultrasonic transducer provided by the embodiment of the present application, as shown in Figure 2, in a possible implementation, the film layer 13 is located on the protective shell 11, and the film layer 13 and The outer wall of the protective shell 11 is connected, so that after the ultrasonic transducer 1 is assembled, the film layer 13 can be pasted on the outer wall of the protective shell 11 , which facilitates subsequent replacement of the film layer 13 .
  • the film layer 13 is bonded to the inner wall of the accommodating chamber 14 or the film layer 13 is bonded to the outer wall of the protective shell 11 .
  • the film layer 13 is covered on the sound outlet 111 by bonding, which is easy to operate and has a good sealing effect.
  • the film layer 13 can be bonded to the inner wall of the accommodating chamber 14 by using silicone sealant, or the film layer 13 can be bonded to the outer wall of the protective shell 11 by using silicone sealant.
  • the sound outlet 111 is a round hole.
  • the sound outlet 111 may be a circular through hole, or the sound outlet 111 may be a circular stepped hole, wherein the large-diameter end of the sound outlet 111 is close to the accommodation cavity 14 , and the small-diameter end of the sound outlet 111 is close to the outside.
  • the film layer 13 is also circular, and the diameter of the film layer 13 should be larger than the diameter of the sound outlet 111 to facilitate the bonding of the film layer 13 and the protective shell 11 .
  • the film layer 13 When the sound outlet 111 is a circular step hole, if the film layer 13 is located in the housing chamber 14, the film layer 13 is connected to the inner wall of the housing chamber 14, and the diameter of the film layer 13 should be greater than the diameter of the large diameter end of the sound outlet 111 size.
  • the film layer 13 is located on the protective shell 11, and the film layer 13 is connected to the outer wall of the protective shell 11. At this time, the diameter of the film layer 13 should be larger than the diameter of the small diameter end of the sound outlet 111. In this way, it is beneficial for the film layer 13 to be firmly fixed.
  • the film layer 13 is also rectangular, and the length and width of the film layer 13 are larger than the length and width of the sound outlet.
  • Fig. 3 is a schematic structural diagram of the film layer in the ultrasonic transducer provided by the embodiment of the present application.
  • the membrane layer 13 has pores 131 .
  • the membrane layer 13 is a waterproof membrane, and the membrane layer 13 is a thermoplastic polyester layer.
  • thermoplastic polyester mainly includes polyethylene terephthalate (PET for short) and polybutylene terephthalate (PBT for short), both of which are mostly used as high-performance films.
  • the waterproof membrane is a microporous film stretched from polyethylene terephthalate PET.
  • the molecular structure of PET plastic is highly symmetrical and has a certain crystal orientation ability, so it has a higher Film forming.
  • the waterproof membrane has pores 131, and the diameter of the pores 131 of the waterproof membrane is 0.4 ⁇ m-0.44 ⁇ m.
  • the waterproof membrane has pores 131, but the diameter of the pores 131 is less than 1 ⁇ m, and it is difficult for water molecules to penetrate the waterproof membrane.
  • the sound transmission performance of the waterproof membrane is jointly determined by the above two sound transmission methods.
  • the sound transmission performance depends on the Rayleigh damping caused by the porosity of the waterproof membrane. The larger the porosity, the lower the loss of sound transmission, but the worse the waterproof performance.
  • the passive radiation efficiency of sound waves depends on the material parameters and dimensions of the waterproofing membrane.
  • the diameter of the pores 131 of the waterproof membrane is set to 0.4 ⁇ m-0.44 ⁇ m.
  • the film layer 13 is a dust-proof film, and the dust-proof film has pores 131 , and the diameter of the pores 131 of the dust-proof film is 18 ⁇ m-260 ⁇ m.
  • the dust-proof film is a woven mesh film made of corrosion-resistant metal or engineering plastics, such as a stainless steel woven mesh film, etc.
  • the dust-proof film can prevent large particles of dust, sand, and metal particles from moving with the airflow. Destructive shock to the device.
  • it can be fixed on the protective shell 11 by means of welding (such as laser welding) and bonding (such as various adhesives such as acrylic).
  • the arrangement of the pores 131 on the membrane layer 13 can be arranged in an equidistant regular distribution manner or in a random distribution manner, and this embodiment does not limit the arrangement manner of the pores 131 on the membrane layer 13 .
  • the working frequency of the ultrasonic transducer 1 is a known parameter
  • the resonant frequency of the film layer 13 is the same as the working frequency of the ultrasonic transducer 1 , thus, the resonant frequency of the film layer 13 is also a known parameter.
  • the thickness of the film layer 13 can be calculated by using Formula 1 and Formula 2, so as to select the film layer 13 with the same working frequency as the ultrasonic transducer 1 .
  • f tp in the formula 1 is the resonant frequency of the film layer 13
  • K n is a constant
  • the value of K n is 10.22
  • ⁇ is the density of the film layer 13
  • d m is the thickness of the film layer 13
  • R is the sound outlet 111 the radius of
  • D E is the bending stiffness of the film layer 13
  • E is the equivalent Young's modulus of the film layer 13
  • d m is the thickness of the film layer 13
  • ⁇ is the Poisson's ratio of the film layer 13 .
  • the material of the waterproof membrane is polyethylene terephthalate PET, its density ⁇ is 1.38g/m3, the equivalent Young's modulus E is 2.8-3.5GPa, and Poisson's ratio ⁇ is 0.3- 0.4.
  • the resonant frequency of the membrane layer 13 is the same as the working frequency of the ultrasonic transducer 1 , that is, the resonant frequency f tp of the membrane layer 13 is 80 kHz.
  • the sound outlet 111 is a circular step hole
  • the film layer 13 is located in the housing chamber 14, the film layer 13 is connected to the inner wall of the housing 11 of the housing chamber 14, and the radius R of the sound outlet 111 is The radius dimension value of the large diameter end of the sound port 111.
  • the film layer 13 is positioned on the protective shell 11, and the film layer 13 is connected with the outer wall of the protective shell 11. At this time, the radius R of the sound outlet 111 is the radius dimension value of the small diameter end of the sound outlet 111.
  • the bending stiffness D E of the membrane layer 13 and the thickness d m of the membrane layer 13 can be calculated by the above values, so as to complete the selection of the thickness of the membrane layer 13, and make the resonant frequency of the membrane layer 13 and the ultrasonic transducer 1
  • the working frequency is the same, the passive radiation efficiency of sound waves is improved, and the sound transmission performance of the film layer 13 is improved.
  • the protective case 11 includes a base 112 and a cover 113 covering the base 112.
  • the base 112 and the cover 113 jointly form an accommodation cavity 14, and the piezoelectric film 12, the circuit board 15 and the piezoelectric film 12 are placed in the accommodation cavity 14.
  • Chip 16 , piezoelectric film 12 and chip 16 are electrically connected to circuit board 15 .
  • the chip 16 is an amplifier chip, and the amplifier chip communicates with the piezoelectric film 12 to amplify the electrical signal generated by the piezoelectric film 12 .
  • the amplifier chip can be AFIC901N, which is a two-stage high-gain amplifier, which is unmatched even between stages, so performance can be optimized for any frequency in the range of 1.8 to 1000 MHz.
  • the device has high gain, rugged and wideband performance.
  • the sound outlet 111 is positioned on the base 112, the circuit board 15 is connected with the base 112, the position of the circuit board 15 relative to the piezoelectric film 12 is provided with a through hole, the size of the through hole is the same as that of the piezoelectric film 12, and the sound outlet 111 The position corresponds to the position of the through hole of the circuit board 15 , so that the ultrasonic wave generated by the piezoelectric film 12 is transmitted through the through hole of the circuit board 15 and the sound outlet 111 on the base 112 .
  • the piezoelectric film 12 and the chip 16 are covered with an encapsulation layer 18 .
  • the piezoelectric film 12 and the chip 16 are protected against water and dust through the encapsulation layer 18 .
  • FIG. 4 is a schematic structural diagram of a support frame in an ultrasonic transducer provided in an embodiment of the present application
  • FIG. 5 is a schematic structural diagram of another structure of a support frame in an ultrasonic transducer provided in an embodiment of the present application.
  • a support frame 17 is provided on the accommodation cavity 14 , and the piezoelectric film 12 is supported by the support frame 17 , so that the piezoelectric film 12 becomes a suspended structure.
  • the piezoelectric film 12 can be rectangular, and the support frame 17 includes two support columns 171 arranged at intervals, wherein the opposite sides of the support columns 171 have Groove 172 , the piezoelectric film 12 is embedded in the groove 172 of the supporting column 171 .
  • the piezoelectric film 12 can be circular, the support frame 17 is tubular, and the inner wall of the support frame 17 has a support ring 173, and the support ring 173 is used to install the piezoelectric film. 12.
  • the inner diameter of the support ring 173 is larger than the inner diameter of the large diameter end of the sound outlet 111 .
  • the support frame 17 is tubular, the piezoelectric film 12 covers the end surface of the support frame 17 , and the inner diameter of the support frame 17 is larger than the inner diameter of the large diameter end of the sound outlet 111 .
  • the present application also provides an electronic device, including an electronic device body and the ultrasonic transducer 1 provided in the above-mentioned embodiments connected to the electronic device body.
  • the electronic device may be a water level detection device, a sweeping robot or a reversing radar device.
  • the sweeping robot can be equipped with an ultrasonic transducer 1 to realize anti-collision, anti-drop, edge detection, etc. of the sweeping robot.
  • the reversing radar device can realize the detection of the whole vehicle without blind spots, and can even completely establish the ultrasonic imaging around the whole vehicle to assist the intelligent driving system.
  • the electronic device provided in this embodiment is provided with the electronic device body and the ultrasonic transducer 1 provided in the above-mentioned embodiment.
  • the ultrasonic transducer 1 includes a film layer 13, and the resonant frequency of the film layer 13 is the same as the working frequency of the ultrasonic transducer 1. , the sound permeability of the film layer 13 is improved, so that the ultrasonic transducer 1 of the electronic device can be protected from dust or water while the detection distance of the ultrasonic transducer 1 will not be reduced. In this way, the failure of the ultrasonic transducer 1 The rate is reduced, and the reliability of the electronic equipment as a whole is improved.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
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  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Transducers For Ultrasonic Waves (AREA)

Abstract

一种超声换能器（1）及电子设备，超声换能器（1）包括保护壳（11）、压电薄膜（12）和膜层（13）；保护壳（11）内具有容纳腔（14），压电薄膜（12）位于容纳腔（14）内；保护壳（11）上具有与容纳腔（14）连通的出音口（111），出音口（111）与压电薄膜（12）相对；膜层（13）覆盖在出音口（111）上，膜层（13）的共振频率与超声换能器（1）的工作频率相同，提高了超声换能器（1）的灵敏度。

Description

超声换能器及电子设备
本申请要求于2021年10月25日提交国家知识产权局、申请号为202111241786.2、发明名称为“超声换能器及电子设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及防水膜技术，例如涉及一种超声换能器及电子设备。
背景技术
超声雷达通过超声波信号的发送与接收时间计算得到超声雷达到目标面的距离。超声雷达已经被广泛应用与自动泊车系统中。
随着消费类电子产品小型化的趋势越来越明显，多家公司推出了一种基于压电薄膜的超声换能器，来取代传统的车载超声雷达。这种超声换能器已经被应用于AR/VR，电子门锁以及扫地机器人。
但是，相关技术中超声换能器采用的防水方式，使超声换能器的灵敏度损耗较大。
发明内容
本申请提供一种超声换能器及电子设备，提高了超声换能器的灵敏度。
第一方面，本申请提供一种超声换能器，包括保护壳、压电薄膜和膜层；
保护壳内具有容纳腔，压电薄膜位于容纳腔内；
保护壳上具有与容纳腔连通的出音口，出音口与压电薄膜相对；
膜层覆盖在出音口上，膜层的共振频率与超声换能器的工作频率相同。
在一种可能的实现方式中，本申请提供的超声换能器，膜层位于容纳腔内，且膜层与容纳腔的内壁连接；
或者，膜层位于保护壳上，且膜层与保护壳的外壁连接。
在一种可能的实现方式中，本申请提供的超声换能器，膜层与容纳腔的内壁粘接；
或者，膜层与保护壳的外壁粘接。
在一种可能的实现方式中，本申请提供的超声换能器，出音口为圆孔。
在一种可能的实现方式中，本申请提供的超声换能器，膜层为防水膜，膜层为热塑性聚酯层。
在一种可能的实现方式中，本申请提供的超声换能器，膜层具有孔隙，孔隙直径为0.4μm-0.44μm。
在一种可能的实现方式中，本申请提供的超声换能器，膜层的厚度通过公式一和公式二计算；
Figure PCTCN2022089833-appb-000001
Figure PCTCN2022089833-appb-000002
其中，公式一中f tp为膜层的共振频率，K n为常数，K n的数值为10.22，ρ为膜层的密度，d m为膜层的厚度，R为出音口的半径；
公式二中，D E为膜层的弯曲刚度，E为膜层的等效杨氏模量，d m为膜层的厚度，μ为膜层的泊松比。
在一种可能的实现方式中，本申请提供的超声换能器，保护壳包括底座和覆盖在底座上的壳罩，底座和壳罩共同形成容纳腔，出音口位于底座上。
在一种可能的实现方式中，本申请提供的超声换能器，还包括电路板和芯片；
压电薄膜和芯片与电路板电连接；
电路板连接在底座上；
压电薄膜和芯片上覆盖有封装层。
第二方面，本申请提供一种电子设备，包括电子设备本体和与电子设备本体连接的上述第一方面提供的超声换能器。
本申请提供的超声换能器及电子设备，超声换能器通过设置保护壳、压电薄膜和膜层，保护壳内具有容纳腔，保护壳上具有与容纳腔连通的出音口，压电薄膜位于容纳腔内，出音口与压电薄膜相对，膜层覆盖在出音口上，且膜层的共振频率与超声换能器的工作频率相同，从而使压电薄膜产生的超声波通过出音口和膜层传出。利用膜层对超声换能器进行防水或防尘保护，膜层的共振频率与超声换能器的工作频率相同，由此提高了膜层的透声性能，从而减小超声波通过膜层时产生的损耗，避免超声换能器探测距离的下降。
附图说明
为了更清楚地说明本申请实施例或相关技术中的技术方案，下面将对实施例或相关技术描述中所需要使用的附图作一简单地介绍，显而易见地，下面描述中的附图是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本申请实施例提供的超声换能器的结构示意图；
图2为本申请实施例提供的超声换能器中膜层的连接位置示意图；
图3为本申请实施例提供的超声换能器中膜层的结构示意图；
图4为本申请实施例提供的超声换能器中支撑架的结构示意图；
图5为本申请实施例提供的超声换能器中支撑架的另一种结构示意图。
附图标记说明：
1-超声换能器；
11-保护壳；
111-出音口；
112-底座；
113-壳罩；
12-压电薄膜；
13-膜层；
131-孔隙；
14-容纳腔；
15-电路板；
16-芯片；
17-支撑架；
171-支撑柱；
172-凹槽；
173-支撑环；
18-封装层。
具体实施方式
在本申请的描述中，需要说明的是，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”应作广义理解，例如，可以是固定连接，也可以是通过中间媒介间接相连，可以是两个元件内部的连通或者两个元件的相互作用关系。对于本领域的普通技术人员而言，可以根据情况理解上述术语在本申请中的含义。
在本申请的描述中，需要理解的是，术语“上”、“下”、“前”、“后”、“竖直”、“水平”、“顶”、“底”、“内”、“外”等指示的方位或者位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请和简化描述，而不是指示或者暗示所指的装置或者元件具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请的限制。
本申请的说明书和权利要求书及上述附图中的术语“第一”、“第二”、“第三”(如果存在)是用于区别类似的对象，而不必用于描述特定的顺序或先后次序。应该理解这样使用的数据在适当情况下可以互换，以便这里描述的本申请的实施例例如能够以除了在这里图示或描述的那些以外的顺序实施。
此外，术语“包括”和“具有”以及他们的任何变形，意图在于覆盖不排他的包含，例如，包含了一系列步骤或单元的过程、方法、系统、产品或维护工具不必限于清楚地列出的那些步骤或单元，而是可包括没有清楚地列出的或对于这些过程、方法、产品或维护工具固有的其它步骤或单元。
为使本申请实施例的目的、技术方案和优点更加清楚，下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
超声雷达通过超声波信号的发送与接收时间计算得到超声雷达到目标面的距离。超声雷达已经被广泛应用与自动泊车系统中。随着消费类电子产品小型化的趋势越来越明显，多家公司推出了一种基于压电薄膜的超声换能器，来取代传统的车载超声雷达。这种超声换能器已经被应用于AR/VR，电子门锁以及扫地机器人。超声换能器不能防水，这极大地限制了它的用途。为了实现超声换能器的防水，通常在超声换能器上设置防水膜对超声换能器进行保护。但是，相关技术中设置的防水膜透声性能差，使超声波传播过程中的损耗较大。
为了解决上述技术问题，本申请提供一种超声换能器及电子设备，通过在超声换能器的出音口设置膜层对超声换能器进行保护，膜层的共振频率与超声换能器的工作频率相同，这样，可以提高膜层的透声性能，减小超声波通过膜层时的损耗，从而避免超声换能器探测距离的下降。
下面结合附图和实施例对本申请进行说明。
图1为本申请实施例提供的超声换能器的结构示意图，参见图1所示，本申请提供的超声换能器1，包括保护壳11、压电薄膜12和膜层13，保护壳11内具有容纳腔14，压电薄膜12位于容纳腔14内。
其中，保护壳11上具有与容纳腔14连通的出音口111，出音口111与压电薄膜12相对。
膜层13覆盖在出音口111上，膜层13的共振频率与超声换能器1的工作频率相同。
在一实施例中，膜层13可以为防尘膜或者防水膜。这样，通过膜层13的设置可以对超声换能器1进行有效的保护，避免灰尘、砂石等颗粒物质或者水、油等液体通过出音口111进入到容纳腔14内，从而对超声换能器1的工作性能造成影响。
其中，压电薄膜12的边缘固定在容纳腔14内，中间位置悬空设置。
压电薄膜12通过压电材料的正逆压电效应产生振动，从而发射或者接收超声波信号。压电薄膜12既可做执行器(发射声波)，又可以做传感器(接收声波)。
示例性的，压电薄膜12采用的压电材料可以为氮化铝(AlN)或锆钛酸铅(PZT)。
示例性的，保护壳11可以为金属壳或者塑料壳，利用保护壳11对容纳腔14内的器件进行保护，避免内部器件被碰撞冲击。
膜层13的共振频率与超声换能器1的工作频率相同，示例性的，超声换能器1的工作频率为80kHz。
当膜层13与超声换能器1发生共振时，即膜层13的共振频率为80kHz时，膜层13的声阻抗达到最小值。这样，可以提高膜层13的透声性能，使超声波通过膜层13时不产生损耗，从而避免超声换能器1探测距离的下降。
工作时，给压电薄膜12电极施加电压，压电薄膜12发生弯曲振动，推动空气产生超声波。超声波经出音口111与膜层13传到外部空气中，遇到目标物之后反射回来。反射的超声波透过膜层13之后激起压电薄膜12的振动，压电薄膜12将振动信号转化成电信号。这样，处理系统通过计算压电薄膜12收发超声信号的时间，将时间乘以声速可得到超声换能器1到目标物的距离。
本实施例提供的超声换能器1，通过设置保护壳11、压电薄膜12和膜层13，保护壳11内具有容纳腔14，保护壳11上具有与容纳腔14连通的出音口111，压电薄膜12位于容纳腔14内，出音口111与压电薄膜12相对，膜层13覆盖在出音口111上，且膜层13的共振频率与超声换能器1的工作频率相同，从而使压电薄膜12产生的超声波通过出音口111和膜层13传出。利用膜层13对超声换能器1进行防水或防尘保护，膜层13的共振频率与超声换能器1的工作频率相同，由此提高了膜层13的透声性，从而减小了超声波通过膜层13时产生的损耗，避免超声换能器1探测距离的下降。
请继续参见图1所示，在一种可能的实现方式中，膜层13位于容纳腔14内，且膜层13与保护壳11中的容纳腔14的内壁连接，这样，可以将膜层13设置在超声换能器1内，通过保护壳11保护膜层13，使膜层13不易与保护壳11脱离，从而提高膜层13的使用寿命。
图2为本申请实施例提供的超声换能器中膜层的连接位置示意图，参见图2所示，在一种可能的实现方式中，膜层13位于保护壳11上，且膜层13与保护壳11的外壁连接，这样，可以将超声换能器1组装完成后，再将膜层13粘贴在保护壳11的外壁上，这样，方便膜层13后续的更换。
其中，膜层13与容纳腔14的内壁粘接或者膜层13与保护壳11的外壁粘接。
采用粘接的方式，将膜层13覆盖在出音口111上，操作简单，密封效果好。示例性的，可以利用有机硅密封胶将膜层13与容纳腔14的内壁进行粘接，或者利用有机硅密封胶将膜层13与保护壳11的外壁粘接。
在本实施例中，出音口111为圆孔。
在一个实施例中，出音口111可以为圆形通孔，或者出音口111为圆形台阶孔，其中出音口111大径端靠近容纳腔14，出音口111小径端靠近外部。
可以理解的，膜层13同样为圆形，膜层13的直径应大于出音口111的直径，方便膜层13与保护壳11的粘接。
当出音口111为圆形台阶孔时，若膜层13位于容纳腔14内，膜层13与容纳腔14的内壁连接，这时膜层13的直径应该大于出音口111大径端的直径尺寸。膜层13位于保护壳11上，膜层13与保护壳11的外壁连接，这时膜层13的直径应该大于出音口111小径端的直径尺寸。这样，有利于膜层13固定牢固。
当出音口111为矩形孔时，膜层13同样为矩形，且膜层13的长度与宽度大于出音口的长度与宽度。
图3为本申请实施例提供的超声换能器中膜层的结构示意图。参见图3所示，膜层13具有孔隙131。
在一些实施例中，膜层13为防水膜，膜层13为热塑性聚酯层。
其中，热塑性聚酯主要包括聚对苯二甲酸乙二酯(Polyethylene terephthalate，简称PET)和聚对苯二甲酸丁二酯(polybutylene terephthalate，简称PBT)，两者多用作高性能薄膜。
在本实施例中，防水膜是由聚对苯二甲酸乙二酯PET拉伸而成的自带微孔的薄膜，PET塑料分子结构高度对称，具有一定的结晶取向能力，故而具有较高的成膜性。
其中，防水膜具有孔隙131，防水膜的孔隙131直径为0.4μm-0.44μm。
防水膜具有孔隙131，但是孔隙131直径不到1μm，水分子难以穿透防水膜。
声音穿过防水膜的方式有两种：主动穿透与被动辐射。防水膜的透声性能由上述两种透声方式共同决定。声音的透射性能取决于防水膜的孔隙率导致的瑞利阻尼。孔隙率越大， 声音的透射的损耗越低，但是防水性能越差。声波的被动辐射效率取决于防水膜的材料参数和尺寸。
可以理解的，在孔隙131与孔隙131之间间隔距离一定的情况下，防水膜孔隙131直径越大，防水膜的孔隙率越大，防水膜孔隙131直径越小，防水膜的孔隙率越小，为了使平衡防水膜的声音透射性能和防水性能，将防水膜的孔隙131直径设置为0.4μm-0.44μm。
在一些实施例中，膜层13为防尘膜，防尘膜上具有孔隙131，防尘膜的孔隙131直径为18μm-260μm。
其中，防尘膜为抗腐蚀性金属或工程塑料材质的织网状膜层，如不锈钢织网状膜层等，防尘膜能够防止大颗粒灰尘和砂石、金属颗粒随气流运动而对内部器件的破坏性冲击。在组装过程中可以通过焊接(如激光焊)和粘接(如丙烯酸类等多种粘接剂)的方式固定在保护壳11上。
需要说明的是，膜层13上的孔隙131的排布方式可以采用为等间距规律分布的方式也可以为随机分布的方式，本实施例对膜层13上孔隙131的排布方式不做限定。
在实现时，超声换能器1的工作频率为已知参数，膜层13的共振频率与超声换能器1的工作频率相同，由此，膜层13的共振频率也为已知参数。
可以利用公式一和公式二，对膜层13的厚度进行计算，从而选择与超声换能器1的工作频率相同的膜层13。
Figure PCTCN2022089833-appb-000003
Figure PCTCN2022089833-appb-000004
其中，公式一中f tp为膜层13的共振频率，K n为常数，K n的数值为10.22，ρ为膜层13的密度，d m为膜层13的厚度，R为出音口111的半径；
公式二中，D E为膜层13的弯曲刚度，E为膜层13的等效杨氏模量，d m为膜层13的厚度，μ为膜层13的泊松比。
在一个实施例中，防水膜的材料为聚对苯二甲酸乙二酯PET，其密度ρ为1.38g/m3，等效杨氏模量E为2.8-3.5GPa，泊松比μ为0.3-0.4。
膜层13的共振频率与超声换能器1的工作频率相同，即膜层13的共振频率f tp为80kHz。
可以理解的是，当出音口111为圆形台阶孔时，若膜层13位于容纳腔14内，膜层13与容纳腔14保护壳11的内壁连接，出音口111的半径R为出音口111大径端的半径尺寸值。膜层13位于保护壳11上，膜层13与保护壳11的外壁连接，这时出音口111的半 径R为出音口111小径端的半径尺寸值。
这样，通过上述数值可以计算出膜层13的弯曲刚度D E以及膜层13的厚度d m，从而完成对膜层13的厚度的选择，使膜层13的共振频率与超声换能器1的工作频率相同，提高声波的被动辐射效率，提高膜层13的透声性能。
在一些实施例中，保护壳11包括底座112和覆盖在底座112上的壳罩113，底座112和壳罩113共同形成容纳腔14，容纳腔14内放置有压电薄膜12、电路板15和芯片16，压电薄膜12和芯片16与电路板15电连接。
在一个实施例中，芯片16为放大器芯片，放大器芯片与压电薄膜12连通，以对压电薄膜12产生的电信号进行放大处理。
示例性的，放大器芯片可以为AFIC901N，AFIC901N是一个两级高增益放大器，该器件即使在级间也是未匹配的，因此可对1.8至1000MHz范围内的任何频率进行性能优化。该器件拥有高增益、耐用和宽带性能。
其中，出音口111位于底座112上，电路板15与底座112连接，电路板15相对于压电薄膜12的位置设置有通孔，通孔尺寸与压电薄膜12尺寸相同，出音口111位置与电路板15通孔位置相对应，从而使压电薄膜12产生的超声波通过电路板15的通孔及底座112上的出音口111传出。
其中，压电薄膜12和芯片16上覆盖有封装层18。通过封装层18从而对压电薄膜12和芯片16进行防水和防尘保护。
图4为本申请实施例提供的超声换能器中支撑架的结构示意图，图5为本申请实施例提供的超声换能器中支撑架的另一种结构示意图。参见图4和5所示，容纳腔14上设置有支撑架17，利用支撑架17来支撑压电薄膜12，使压电薄膜12成为悬空结构。
在一种可能的实现方式中，参见图4所示，压电薄膜12可以为矩形，支撑架17包括两个支撑柱171，两个支撑柱171间隔设置，其中，支撑柱171相对的两面具有凹槽172，压电薄膜12嵌入到支撑柱171的凹槽172内。
在另一种可能的实现方式中，参见图5所示，压电薄膜12可以为圆形，支撑架17为管状，支撑架17的内壁具有支撑环173，支撑环173用于安装压电薄膜12。其中，支撑环173的内径尺寸大于出音口111大径端的内径尺寸。或者，支撑架17为管状，压电薄膜12覆盖在支撑架17的端面上，支撑架17的内径大于出音口111大径端的内径尺寸。
本申请还提供一种电子设备，包括电子设备本体和与电子设备本体连接的上述实施例提供的超声换能器1。
其中，超声换能器1的结构和原理在上述实施例中进行了详细说明，本实施例在此不一一赘述。
示例性的，电子设备可以为水位检测设备、扫地机器人或者倒车雷达装置。
扫地机器人可以设置超声换能器1以实现扫地机器人的防碰撞、防跌落、边缘检测等。倒车雷达装置通过在车辆的四周设置超声换能器1可以实现全车无盲区检测，甚至可以完整建立环绕全车的超声成像以辅助智能驾驶系统。
本实施例提供的电子设备通过设置电子设备本体和上述实施例提供的超声换能器1，超声换能器1包括膜层13，膜层13的共振频率与超声换能器1的工作频率相同，膜层13的透声性能提高，从而实现对电子设备的超声换能器1进行防尘或者防水保护的同时不会降低超声换能器1的探测距离，这样，超声换能器1的故障率降低，电子设备整体的可靠性提高。
最后应说明的是：以上各实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述各实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的范围。

Claims (10)

  1. 一种超声换能器，其中，包括保护壳、压电薄膜和膜层；
    所述保护壳内具有容纳腔，所述压电薄膜位于所述容纳腔内；
    所述保护壳上具有与所述容纳腔连通的出音口，所述出音口与所述压电薄膜相对；
    所述膜层覆盖在所述出音口上，所述膜层的共振频率与所述超声换能器的工作频率相同。
  2. 根据权利要求1所述的超声换能器，其中，所述膜层位于所述容纳腔内，且所述膜层与所述容纳腔的内壁连接；
    或者，所述膜层位于所述保护壳上，且所述膜层与所述保护壳的外壁连接。
  3. 根据权利要求2所述的超声换能器，其中，所述膜层与所述容纳腔的内壁粘接；
    或者，所述膜层与所述保护壳的外壁粘接。
  4. 根据权利要求1至3任一项所述的超声换能器，其中，所述出音口为圆孔。
  5. 根据权利要求1至3任一项所述的超声换能器，其中，所述膜层为防水膜，所述膜层为热塑性聚酯层。
  6. 根据权利要求5所述的超声换能器，其中，所述膜层具有孔隙，所述孔隙直径为0.4μm-0.44μm。
  7. 根据权利要求4所述的超声换能器，其中，所述膜层的厚度通过公式一和公式二计算；
    Figure PCTCN2022089833-appb-100001
    Figure PCTCN2022089833-appb-100002
    其中，公式一中f tp为所述膜层的共振频率，K n为常数，K n的数值为10.22，ρ为所述膜层的密度，d m为所述膜层的厚度，R为所述出音口的半径；
    公式二中，D E为所述膜层的弯曲刚度，E为所述膜层的等效杨氏模量，d m为所述膜层的厚度，μ为所述膜层的泊松比。
  8. 根据权利要求1至3任一项所述的超声换能器，其中，所述保护壳包括底座和覆盖在所述底座上的壳罩，所述底座和所述壳罩共同形成所述容纳腔，所述出音口位于所述底座上。
  9. 根据权利要求8所述的超声换能器，其中，还包括电路板和芯片；
    所述压电薄膜和所述芯片与所述电路板电连接；
    所述电路板连接在所述底座上；
    所述压电薄膜和所述芯片上覆盖有封装层。
  10. 一种电子设备，其中，包括电子设备本体和与所述电子设备本体连接的权利要求1至9任一项所述的超声换能器。
PCT/CN2022/089833 2021-10-25 2022-04-28 超声换能器及电子设备 WO2023071107A1 (zh)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020135272A1 (en) * 2001-01-02 2002-09-26 Minoru Toda Curved film electrostatic ultrasonic transducer
CN2802521Y (zh) * 2004-11-05 2006-08-02 葛立峰 双模静电超声传感器
CN206930774U (zh) * 2017-06-16 2018-01-26 苏州宝时得电动工具有限公司 一种超声波传感器
CN209968843U (zh) * 2018-02-22 2020-01-21 意法半导体股份有限公司 用于在传播介质中发射超声声波的设备和电子系统
CN111796291A (zh) * 2019-04-05 2020-10-20 株式会社电装 超声传感器

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020135272A1 (en) * 2001-01-02 2002-09-26 Minoru Toda Curved film electrostatic ultrasonic transducer
CN2802521Y (zh) * 2004-11-05 2006-08-02 葛立峰 双模静电超声传感器
CN206930774U (zh) * 2017-06-16 2018-01-26 苏州宝时得电动工具有限公司 一种超声波传感器
CN209968843U (zh) * 2018-02-22 2020-01-21 意法半导体股份有限公司 用于在传播介质中发射超声声波的设备和电子系统
CN111796291A (zh) * 2019-04-05 2020-10-20 株式会社电装 超声传感器

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