WO2022007043A1 - 压电超声换能器 - Google Patents

压电超声换能器 Download PDF

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Publication number
WO2022007043A1
WO2022007043A1 PCT/CN2020/105088 CN2020105088W WO2022007043A1 WO 2022007043 A1 WO2022007043 A1 WO 2022007043A1 CN 2020105088 W CN2020105088 W CN 2020105088W WO 2022007043 A1 WO2022007043 A1 WO 2022007043A1
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piezoelectric
electrode
piezoelectric unit
layer
structural layer
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PCT/CN2020/105088
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English (en)
French (fr)
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石正雨
童贝
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瑞声声学科技(深圳)有限公司
瑞声科技（南京）有限公司
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Publication of WO2022007043A1 publication Critical patent/WO2022007043A1/zh

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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/05—Manufacture of multilayered piezoelectric or electrostrictive devices, or parts thereof, e.g. by stacking piezoelectric bodies and electrodes

Definitions

  • the present application relates to the field of ultrasonic sensors, and in particular, to a piezoelectric ultrasonic transducer.
  • Piezoelectric ultrasonic transducer is a device that converts electrical energy and mechanical energy into each other. It uses the piezoelectric properties of piezoelectric diaphragms to generate vibrational motion to emit sound.
  • a piezoelectric ultrasonic transducer in the prior art includes a base 110 with a cavity 111 in the center, and a diaphragm 120 fixed on the base 110 and covering the cavity 111 .
  • the connected structural layer 121 and the piezoelectric unit 122 attached above the structural layer 121.
  • the piezoelectric unit 122 includes a first electrode 1221 close to the structural layer, a second electrode 1222 far from the structural layer 121, and a second electrode 1222 sandwiched between the first electrode 1221.
  • the piezoelectric layer 1223 between the second electrode 1222 and the first electrode 1221 and the second electrode 1222 are connected to the power supply, the piezoelectric layer 1223 is excited by the alternating electric field/magnetic field to generate lateral expansion and deformation, thereby driving the structural layer 121 to deform, and the Electrical energy is converted into mechanical energy.
  • the thickness of the structural layer 121 is thickened in the prior art. The thickness is greater than that of the piezoelectric unit 122 , but the thickening of the structural layer 121 results in more mechanical energy being stored in the structural layer 121 and also reduces the electromechanical conversion efficiency of the piezoelectric ultrasonic transducer.
  • the purpose of the present application is to provide a piezoelectric ultrasonic transducer with higher electromechanical conversion efficiency.
  • a piezoelectric ultrasonic transducer includes a base and a vibrating membrane, a cavity is arranged in the center of the base, the vibrating membrane includes a structural layer, a first piezoelectric unit and a second piezoelectric unit, the structural layer and the The base is fixedly connected and covers the cavity, the first piezoelectric unit is connected to the upper surface of the structural layer facing away from the cavity, and the second piezoelectric unit faces the structural layer The lower surface of the cavity is connected; the first piezoelectric unit includes a first electrode close to the structure layer, a second electrode away from the structure layer, and a second electrode sandwiched between the first electrode and the second electrode.
  • a first piezoelectric layer between two electrodes; the piezoelectric unit includes a third electrode close to the structural layer, a fourth electrode far from the structural layer, and a fourth electrode sandwiched between the third electrode and the fourth electrode the second piezoelectric layer in between.
  • the neutral plane of the entire diaphragm is kept away from the first piezoelectric unit, so that the thickness of the structural layer can be reduced, the mechanical energy stored in the structural layer can be reduced, and the piezoelectric ultrasonic conversion can be improved.
  • the electromechanical conversion efficiency of the energy device can be improved.
  • the first piezoelectric unit and the second piezoelectric unit can provide lateral expansion and contraction at the same time, thereby increasing the sound pressure.
  • FIG. 1 is a schematic cross-sectional structure diagram of a piezoelectric ultrasonic transducer in the prior art.
  • FIG. 2 is a schematic cross-sectional structure diagram of a piezoelectric ultrasonic transducer according to a specific embodiment of the present application.
  • the present application discloses a piezoelectric ultrasonic transducer, including a base 210 and a vibrating membrane 220 , a cavity 211 is provided in the center of the base 210 , and the vibrating membrane 220 includes a structure layer 221 , a first piezoelectric unit 224 and The second piezoelectric unit 223, the structural layer 221 is fixedly connected to the substrate 210 and covers the cavity 211, the first piezoelectric unit 224 is connected to the upper surface 1211 of the structural layer 221 facing away from the cavity 211, and the second piezoelectric unit 223 is connected to The lower surface 1212 of the structure layer 221 facing the cavity 211 is connected; the first piezoelectric unit 224 includes a first electrode 2241 close to the structure layer 221 , a second electrode 2242 away from the structure layer 221 and sandwiched between the first electrode 2241 and the The first piezoelectric layer 2243 between the second electrodes 2242; the second piezoelectric unit 223
  • the addition of the second piezoelectric unit 223 keeps the neutral plane of the entire diaphragm 220 away from the first piezoelectric unit 224, so that the thickness of the structural layer 221 can be reduced, the mechanical energy stored in the structural layer 221 can be reduced, and the piezoelectric ultrasonic transducer can be improved.
  • the electromechanical conversion efficiency of the device is the electromechanical conversion efficiency of the device.
  • the potentials of the first electrode 2241 and the fourth electrode 2232 are the same, which is set as the first potential, and the potentials of the second electrode 2242 and the third electrode 2231 are the same, which are set as the second potential.
  • One of the potentials is grounded, and the other of the first potential and the second potential is used as an output terminal for receiving signals.
  • the first piezoelectric unit 224 provides tensile deformation
  • the first piezoelectric unit 224 drives the structural layer 221 to arch toward the first piezoelectric unit 224
  • the second piezoelectric unit 223 provides contraction deformation
  • the second piezoelectric unit 223 Drive the structural layer 221 to continue to arch toward the first piezoelectric unit 224.
  • the first piezoelectric unit 224 and the second piezoelectric unit 223 can simultaneously provide lateral expansion and contraction of the structural layer 221, increase the deformation amplitude of the structural layer 221, and increase the sound pressure. .
  • the so-called neutral plane is an imaginary plane in which the lateral dimension does not change during the deformation process of the diaphragm 220, and the lateral deformation tendency of the diaphragm 220 on both sides of the neutral plane is opposite. If the neutral plane is located in the first piezoelectric layer 2243 or the second piezoelectric layer 2233, the piezoelectric layer includes two deformations in opposite directions, which reduces the efficiency of converting electrical energy into mechanical energy, resulting in the electromechanical coupling of the piezoelectric ultrasonic transducer. coefficient drops.
  • the first piezoelectric unit 224 and the second piezoelectric unit 223 are respectively arranged on both sides of the structural layer 221, so as to avoid the decrease of the electromechanical coupling coefficient caused by the opposite deformation of the piezoelectric layer itself, and at the same time, the structural layer can also be greatly reduced. 221 thickness.
  • neither the first piezoelectric unit 224 nor the second piezoelectric unit 223 is in contact with the substrate 210 , which can better relieve the residual stress of the first piezoelectric unit 224 and the second piezoelectric unit 223 .
  • both the first piezoelectric unit 224 and the second piezoelectric unit 223 are disposed in the center of the structure layer 221 .
  • the shape of the first piezoelectric unit 224 may be a circle, a square or a circular ring, etc.; the shape of the second piezoelectric unit 223 may also be a circle, a square or a circular ring, and the like.
  • the shapes of the first piezoelectric unit 224 and the second piezoelectric unit 223 may be the same or different.
  • the second piezoelectric unit 223 may be a circular shape or For circles and squares, etc. nested within a torus.
  • the shape, size, structure and material of the first piezoelectric unit 224 and the second piezoelectric unit 223 are the same, so that the neutral plane of the entire diaphragm 220 can always be located in the structural layer 221, and the structural layer 221
  • the thickness can be arbitrarily set as required.
  • the structural layer 221 is an equal-thickness plate, which is convenient for manufacture.
  • the material of the substrate 210 may be silicon, sapphire, ceramics, glass or polymer, etc.
  • the material of the substrate 210 is silicon.
  • the material of the structure layer 221 can be silicon dioxide, polysilicon, silicon nitride or polymer, etc.
  • the material of the structure layer 221 is silicon dioxide.
  • the material of the first piezoelectric layer 2243 may be aluminum nitride, zinc oxide, or lead zirconate titanate, etc.; the material of the second piezoelectric layer 2233 may be aluminum nitride, zinc oxide, or lead zirconate titanate, or the like.
  • the material of the first piezoelectric layer 2243 and the material of the second piezoelectric layer 2233 may be the same or different. In this embodiment, the materials of the first piezoelectric layer 2243 and the second piezoelectric layer 2233 are the same, and both are lead zirconate titanate piezoelectric ceramics.
  • the material of the first electrode 2241, the second electrode 2242, the third electrode 2231 or the fourth electrode 2232 can be selected from any one of molybdenum, platinum or aluminum.
  • the material of the fourth electrode 2232 may be different or the same.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Transducers For Ultrasonic Waves (AREA)

Abstract

本申请提供了一种压电超声换能器，包括基底和振膜，所述基底的中心设置有空腔，所述振膜包括结构层、第一压电单元和第二压电单元，所述结构层与所述基底固定连接并覆盖所述空腔，所述第一压电单元与所述结构层的背离所述空腔的上表面相连接，所述第二压电单元与所述结构层的朝向所述空腔的下表面相连接；所述第一压电单元包括靠近所述结构层的第一电极、远离所述结构层的第二电极和夹设于所述第一电极和所述第二电极之间的第一压电层；所述第二压电单元包括靠近所述结构层的第三电极、远离所述结构层的第四电极和夹设于所述第三电极和所述第四电极之间的第二压电层。本申请能够降低结构层的厚度，提高机电转换效率，同时，提高声压。

Description

压电超声换能器 技术领域
本申请涉及超声传感器领域，尤其涉及一种压电超声换能器。
 背景技术
压电超声换能器为电能和机械能相互转换的器件，其利用压电膜片的压电特性来产生振动运动从而发出声音。
 技术问题
参考图1，现有技术中的压电超声换能器，包括中心设置有空腔111的基底110和固定在基底110上并覆盖空腔111的振膜120，振膜120包括与基底110相连接的结构层121和贴设在结构层121上方的压电单元122，压电单元122包括靠近结构层的第一电极1221、远离结构层121的第二电极1222和夹设于第一电极1221和第二电极1222之间的压电层1223，第一电极1221和第二电极1222连通电源后，压电层1223受交流电场/磁场激励产生横向伸缩变形，从而带动结构层121产生变形，将电能转换为机械能。
由于压电单元122仅位于结构层121的一侧，为了保证整个振膜120的中性面不位于压电层1223，现有技术中加厚了结构层121的厚度，通常，结构层121的厚度大于压电单元122的厚度，但是，结构层121的增厚，导致结构层121中存储了更多的机械能，也降低了压电超声换能器的机电转换效率。
 技术解决方案
本申请的目的在于提供一种机电转换效率更高的压电超声换能器。
本申请的技术方案如下：
一种压电超声换能器，包括基底和振膜，所述基底的中心设置有空腔，所述振膜包括结构层、第一压电单元和第二压电单元，所述结构层与所述基底固定连接并覆盖所述空腔，所述第一压电单元与所述结构层的背离所述空腔的上表面相连接，所述第二压电单元与所述结构层的朝向所述空腔的下表面相连接；所述第一压电单元包括靠近所述结构层的第一电极、远离所述结构层的第二电极和夹设于所述第一电极和所述第二电极之间的第一压电层；压电单元包括靠近所述结构层的第三电极、远离所述结构层的第四电极和夹设于所述第三电极和所述第四电极之间的第二压电层。
 有益效果
本申请的有益效果在于：
通过在结构层的下表面增加第二压电单元，使整个振膜的中性面远离第一压电单元，从而可以降低结构层的厚度，减少结构层中存储的机械能，提高压电超声换能器的机电转换效率。另一方面，第一压电单元和第二压电单元能够同时提供横向伸缩变形，提高声压。
 附图说明
图1为现有技术中的压电超声换能器的截面结构示意图。
图2为本申请一具体实施例的压电超声换能器的截面结构示意图。
 本发明的实施方式
下面结合附图和实施方式对本申请作进一步说明。
参考图2，本申请公开了一种压电超声换能器，包括基底210和振膜220，基底210的中心设置有空腔211，振膜220包括结构层221、第一压电单元224和第二压电单元223，结构层221与基底210固定连接并覆盖空腔211，第一压电单元224与结构层221的背离空腔211的上表面1211相连接，第二压电单元223与结构层221的朝向空腔211的下表面1212相连接；第一压电单元224包括靠近结构层221的第一电极2241、远离结构层221的第二电极2242和夹设于第一电极2241和第二电极2242之间的第一压电层2243；第二压电单元223包括靠近结构层221的第三电极2231、远离结构层221的第四电极2232和夹设于第三电极2231和第四电极2232之间的第二压电层2233。第二压电单元223的增加，使整个振膜220的中性面远离第一压电单元224，从而可以降低结构层221的厚度，减少结构层221中存储的机械能，提高压电超声换能器的机电转换效率。
优选的，第一电极2241和第四电极2232的电位相同，设为第一电位，第二电极2242和第三电极2231的电位相同，设为第二电位，使用时，第一电位和第二电位二者之一接地，第一电位和第二电位二者之另一作为接受信号的输出端。当第一压电单元224提供拉伸变形时，第一压电单元224驱动结构层221向第一压电单元224方向拱起，第二压电单元223提供收缩变形，第二压电单元223驱动结构层221继续向第一压电单元224方向拱起，第一压电单元224和第二压电单元223能够同时提供结构层221横向伸缩变形，提高结构层221的形变幅度，提高声压。
所谓中性面，即在振膜220变形过程中，横向尺寸不发生变化的假想面，中性面两侧的振膜220，其横向变形的趋势是相反的。若中性面位于第一压电层2243或第二压电层2233，则压电层包括两种方向相反的变形，使电能转换为机械能的效率降低，导致压电超声换能器的机电耦合系数下降。本申请通过在结构层221的两侧分别设置第一压电单元224和第二压电单元223，避免压电层自身变形相反导致的机电耦合系数下降，同时，也能极大的降低结构层221的厚度。
优选的，第一压电单元224和第二压电单元223均不与基底210接触，能够更好的释放第一压电单元224和第二压电单元223的残余应力。
优选的，第一压电单元224和第二压电单元223均设置于结构层221的中心。
第一压电单元224的形状可以为圆形、方形或圆环形等；第二压电单元223的形状为也可以为圆形、方形或圆环形等。第一压电单元224和第二压电单元223的的形状可以相同，也可以不同，当第一压电单元224为圆环形时，第二压电单元223可以为圆环形，也可以为嵌套在圆环形内的圆形和方形等。
优选的，第一压电单元224和第二压电单元223的形状、尺寸、结构和材质均相同，如此，可使整个振膜220的中性面总是位于结构层221中，结构层221的厚度可以根据需要任意设置。
优选的，结构层221为等厚板，便于制造。
基底210的材料可以为硅、蓝宝石、陶瓷、玻璃或聚合物等，优选的，在本实施方式中，基底210的材料为硅。
结构层221的材料可以为二氧化硅、多晶硅、氮化硅或聚合物等，优选的，在本实施方式中，结构层221的材料为二氧化硅。
第一压电层2243的材料可以为氮化铝、氧化锌或锆钛酸铅等；第二压电层2233的材料可以为氮化铝、氧化锌或锆钛酸铅等。第一压电层2243的材料和第二压电层2233的材料可以相同，也可以不同。在本实施方式中，第一压电层2243和第二压电层2233的材料相同，均为锆钛酸铅压电陶瓷。
第一电极2241、第二电极2242、第三电极2231或第四电极2232的材料均可以选自钼、铂或铝中的任意一种，第一电极2241、第二电极2242、第三电极2231和第四电极2232的材料可以不相同，也可以相同。
以上的仅是本申请的实施方式，在此应当指出，对于本领域的普通技术人员来说，在不脱离本申请创造构思的前提下，还可以做出改进，但这些均属于本申请的保护范围。

Claims (7)

  1. 一种压电超声换能器，其特征在于，包括基底和振膜，
    所述基底的中心设置有空腔，所述振膜包括结构层、第一压电单元和第二压电单元，所述结构层与所述基底固定连接并覆盖所述空腔，所述第一压电单元与所述结构层的背离所述空腔的上表面相连接，所述第二压电单元与所述结构层的朝向所述空腔的下表面相连接；
    所述第一压电单元包括靠近所述结构层的第一电极、远离所述结构层的第二电极和夹设于所述第一电极和所述第二电极之间的第一压电层；
    所述第二压电单元包括靠近所述结构层的第三电极、远离所述结构层的第四电极和夹设于所述第三电极和所述第四电极之间的第二压电层。
  2. 根据权利要求1所述的压电超声换能器，其特征在于，所述第一电极和所述第四电极的电位相同，所述第二电极和所述第三电极的电位相同。
  3. 根据权利要求2所述的压电超声换能器，其特征在于，所述第一压电单元和所述第二压电单元均不与所述基底接触。
  4. 根据权利要求3所述的压电超声换能器，其特征在于，所述第一压电单元和所述第二压电单元均设置于所述结构层的中心。
  5. 根据权利要求4所述的压电超声换能器，其特征在于，所述第一压电单元的形状为圆形、方形或圆环形；所述第二压电单元的形状为圆形、方形或圆环形。
  6. 根据权利要求5所述的压电超声换能器，其特征在于，所述第一压电单元和所述第二压电单元的形状、尺寸、结构和材质均相同。
  7. 根据权利要求6所述的压电超声换能器，其特征在于，所述结构层为等厚板。
PCT/CN2020/105088 2020-07-10 2020-07-28 压电超声换能器 WO2022007043A1 (zh)

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CN110350079A (zh) * 2019-07-15 2019-10-18 京东方科技集团股份有限公司 一种压电元件及其制备方法和超声传感器
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