WO2022011606A1 - Ultrasonic transducer and electronic device - Google Patents

Abstract

Provided are an ultrasonic transducer and an electronic device. The ultrasonic transducer comprises: a first electrode layer (1), a piezoelectric layer (2), a second electrode layer (3) and a circuit layer (4), wherein the piezoelectric layer (2) is arranged on the first electrode layer (1); the second electrode layer (3) and the circuit layer (4) are arranged on the piezoelectric layer; a plurality of first grooves are formed in a first surface of the piezoelectric layer (2); each of the first grooves is provided with a recessed surface (21); the orientation of each recessed surface (21) is the same as an acoustic emission direction of the ultrasonic transducer; and a contact angle between the recessed surface (21) and a plane on which the first surface is located is greater than 0 degrees and less than 90 degrees. By using the embodiments of the present application, the emission sensitivity of the ultrasonic transducer can be increased, thereby improving the loop sensitivity of the ultrasonic transducer.

Description

Ultrasound Transducers and Electronics technical field

The embodiments of the present application relate to the technical field of ultrasonic transducers, and in particular, to an ultrasonic transducer and an electronic device.

Background technique

The ultrasonic transducer is a device that converts sound energy and electrical energy into each other. When the piezoelectric material in the ultrasonic transducer is deformed, a voltage difference can be generated at both ends of the piezoelectric material; there is a voltage across the piezoelectric material. When the difference is poor, the piezoelectric material deforms and vibrates to generate ultrasonic waves; using the above characteristics of the piezoelectric material, the mutual conversion between mechanical vibration and alternating current can be realized. The piezoelectric material may be piezoelectric ceramic lead zirconate titanate PZT or polymer piezoelectric material polyvinylidene fluoride PVDF.

Under the condition of the same thickness, the loop sensitivity of PVDF ultrasonic transducer is greater than that of PZT ultrasonic transducer, so PVDF ultrasonic transducer is generally used in portable mobile terminals, but the emission performance of PVDF ultrasonic transducer is poor, which limits the Loop Sensitivity of PVDF Ultrasound Transducers.

SUMMARY OF THE INVENTION

The purpose of the embodiments of the present application is to provide an ultrasonic transducer and an electronic device, which can achieve higher loop sensitivity under the condition of the same thickness, and are more suitable for portable mobile terminals.

An embodiment of the present application provides an ultrasonic transducer, including: a first electrode layer, a piezoelectric layer, a second electrode layer, and a circuit layer; the piezoelectric layer is disposed on the first electrode layer, and a first electrode layer is disposed on the piezoelectric layer Two electrode layers and a circuit layer; a plurality of first grooves are formed on the first surface of the piezoelectric layer, each first groove has a concave surface, and the direction of each concave surface is the same as the sound wave emission direction of the ultrasonic transducer, The contact angle between the concave surface and the plane on which the first surface lies is greater than 0 degrees and less than 90 degrees.

An embodiment of the present application provides an electronic device, including the above-mentioned ultrasonic transducer.

The embodiments of the present application now provide an ultrasonic transducer with respect to the prior art, which includes: a first electrode layer, a piezoelectric layer, a second electrode layer, and a circuit layer, and the piezoelectric layer is disposed on the first electrode layer The piezoelectric layer is provided with a second electrode layer and a circuit layer, a plurality of first grooves are formed on the first surface of the piezoelectric layer, each first groove has a concave surface, and the orientation of each concave surface is the same as that of the ultrasonic wave. The sound wave emission directions of the transducers are the same, and the contact angle between the concave surface and the plane where the first surface is located is greater than 0 degrees and less than 90 degrees. When using the ultrasonic transducer to emit sound waves, the concave surface in the piezoelectric layer can converge the sound waves, reducing the divergence angle of the sound wave emission, and the cavity formed by the concave surface forms an acoustic resonance cavity, which can increase the ultrasonic wave. The transmission sensitivity of the transducer improves the loop sensitivity of the ultrasonic transducer; that is, compared with the prior art, higher loop sensitivity can be achieved under the same thickness condition, which is more suitable for portable mobile terminals. In addition, since the transmit sensitivity can be increased, the requirement for transmit bandwidth is reduced under the condition of the same loop sensitivity.

For example, the concave surface of the first groove of the piezoelectric layer faces the circuit layer, the second electrode layer includes a plurality of first conductive parts, and the plurality of first conductive parts are respectively disposed in the first grooves of the piezoelectric layer. This embodiment provides a specific structure of the second electrode layer when the concave surface of the first groove faces the circuit layer.

For example, an array of hemispherical first grooves is formed on the first surface, the second electrode layer includes an array of hemispherical first conductive parts, and each of the first conductive parts is respectively disposed in each of the first grooves. This embodiment provides an arrangement of the first grooves on the piezoelectric layer.

For example, a plurality of semi-cylindrical first grooves are formed on the first surface, the second electrode layer includes semi-cylindrical first conductive parts arranged in parallel, and the first conductive parts are respectively disposed in the first grooves Inside. This embodiment provides another arrangement of the first grooves on the piezoelectric layer.

For example, the plurality of first conductive parts have first upper surfaces away from the first electrode layer, and the first upper surfaces and the first surface of the piezoelectric layer are on the same plane. This embodiment provides an arrangement of the first conductive portion in the second electrode layer.

For example, the piezoelectric layer includes a plurality of piezoelectric units, each piezoelectric unit includes a second surface opposite to the first surface, a first groove is formed on the first surface of each piezoelectric unit, and the second surface includes The first electrode layer has a plurality of accommodating spaces, a plurality of piezoelectric units are arranged in the accommodating spaces of the first electrode layer, and a plurality of first conductive parts are respectively arranged in the first grooves of the piezoelectric units. A specific structure of the piezoelectric layer is provided in this embodiment.

For example, the first electrode layer has a second upper surface, and the first surface of the piezoelectric layer, the second upper surface of the first electrode layer, and the first upper surface of the first conductive portion are on the same plane. This embodiment provides a specific implementation manner of arranging a plurality of piezoelectric units at intervals.

For example, a plurality of piezoelectric units are arranged at intervals. In this embodiment, a piezoelectric layer for separating piezoelectric films is provided, and a plurality of piezoelectric units are arranged at intervals, which can avoid vibration interference among the plurality of piezoelectric units.

For example, the first electrode layer has a second upper surface, the first surface of the piezoelectric layer and the first upper surface of the first conductive part are on the same plane, and the first surface of the piezoelectric layer and the first surface of the first electrode layer are on the same plane. The two upper surfaces are not on the same plane.

For example, the ultrasonic transducer further includes a plurality of insulating parts, a second groove is formed on the first conductive part, and the insulating part is arranged in the second groove of the first conductive part, so that the insulating part and the piezoelectric layer are spaced apart . In this embodiment, a plurality of insulating parts are added to the ultrasonic transducer, and each insulating part can be arranged at intervals from the piezoelectric layer.

For example, the plurality of insulating portions have a third upper surface remote from the first electrode layer, and the third upper surface is on the same plane as the first surface of the piezoelectric layer. This embodiment provides a specific arrangement of the insulating portion.

For example, the concave surface of the first groove of the piezoelectric layer faces the first electrode layer, the first electrode layer includes a first electrode body and a plurality of second conductive parts, and the first electrode body has a fourth upper surface close to the piezoelectric layer, A plurality of second conductive parts are arranged on the fourth upper surface, and a plurality of second conductive parts are respectively arranged in the first grooves of the piezoelectric layer, the fourth upper surface of the first electrode body, the lower part of the second conductive part The surface and the first surface of the piezoelectric layer are on the same plane. This embodiment provides a specific structure of the first electrode layer when the concave surface of the first groove faces the first electrode layer.

For example, arrayed and hemispherical first grooves are formed on the first surface of the piezoelectric layer, the first electrode layer includes hemispherical second conductive parts arranged in an array, and the second conductive parts are respectively disposed on the piezoelectric layer in each of the first grooves.

For example, a plurality of semi-cylindrical first grooves are formed on the first surface of the piezoelectric layer, the first electrode layer includes semi-cylindrical second conductive parts arranged in parallel, and the second conductive parts are respectively disposed on the piezoelectric layer. in each first groove of the electrical layer.

For example, the ultrasonic transducer also includes a backing layer disposed on the circuit layer. In this embodiment, the reverse propagation of ultrasonic waves in the direction toward the circuit layer can be reduced.

For example, the piezoelectric layer includes a second surface opposite the first surface, the second surface being planar. This embodiment provides a way of disposing the second surface of the piezoelectric layer, so that the piezoelectric layer is easy to manufacture, and is suitable for the piezoelectric thin-film blade coating technology.

For example, the piezoelectric layer includes a second surface opposite to the first surface, and a plurality of protrusions corresponding to the first grooves are formed on the second surface. This embodiment provides another arrangement of the second surface of the piezoelectric layer,

For example, the second electrode layer further includes a second electrode body, a plurality of first conductive parts are formed on the first lower surface of the second electrode body, and the first lower surface and the first surface of the piezoelectric layer are on the same plane; An electrode layer includes a plurality of first sub-electrodes arranged separately, any two first sub-electrodes are insulated from each other, and each of the first sub-electrodes is respectively covered on each of the protruding parts. This embodiment provides a way to individually control each piezoelectric unit when the second electrode layer is a full-surface electrode.

For example, the second electrode layer includes a plurality of second sub-electrodes, any two second sub-electrodes are insulated from each other, each of the second sub-electrodes is covered on each of the protruding parts, and the second sub-electrodes are located between the protruding parts and the protruding parts. between the circuit layers, and the lower surface of the circuit layer close to the piezoelectric layer is on the same plane as the second surface of the piezoelectric layer. In this embodiment, when the protrusions are formed on the second surface of the piezoelectric layer, each piezoelectric unit is individually controlled by the second electrode layer.

For example, the second electrode layer includes a plurality of second sub-electrodes, any two second sub-electrodes are insulated from each other, each of the second sub-electrodes is covered on the back of each of the first grooves, and the second sub-electrodes are located in the protrusions. between the part and the circuit layer, and the lower surface of the circuit layer close to the piezoelectric layer is on the same plane as the second surface of the piezoelectric layer. In this embodiment, when the second surface of the piezoelectric layer is flat, each piezoelectric unit is individually controlled by the second electrode layer.

For example, the second electrode layer covers the second surface of the piezoelectric layer; the first electrode body includes a plurality of third sub-electrodes, any two third sub-electrodes are insulated from each other, and each second conductive part is formed on each on the third sub-electrode. In this embodiment, when the second electrode layer is the front electrode, the first electrode layer is used to individually control each piezoelectric unit.

For example, the concave surface faces the first electrode layer, the first electrode layer includes a plurality of third conductive parts, and the plurality of third conductive parts are respectively arranged in the first grooves of the piezoelectric layer; The second lower surface of the electrode layer, the second lower surfaces of the plurality of third conductive parts and the first surface of the piezoelectric layer are on the same plane; the plurality of first grooves are respectively arranged in the second electrode layer, and any two There is no contact between the first grooves, and the surface of the second electrode layer provided with the first grooves is on the same plane as the first surface of the piezoelectric layer. This embodiment provides a specific way of forming a plurality of first grooves to form piezoelectric units separately when the concave surface faces the first electrode layer, which can avoid vibration interference among the plurality of piezoelectric units.

For example, the insulating portion is matched to the acoustic resistance of the piezoelectric layer. In this embodiment, excessive reflection of acoustic waves between the piezoelectric layer and the second electrode layer and between the second electrode layer and the circuit layer can be avoided, so as to avoid reducing the emission efficiency.

For example, the ultrasonic transducer further includes a functional layer, the first electrode layer is disposed on the functional layer, and the functional layer includes a substrate and/or a backing.

For example, the contact angle ranges from 75 degrees to 90 degrees. In this embodiment, the emission sensitivity of the ultrasonic transducer can be increased as much as possible.

Description of drawings

One or more embodiments are exemplified by the pictures in the corresponding drawings, and these exemplifications do not constitute limitations of the embodiments, and elements with the same reference numerals in the drawings are denoted as similar elements, Unless otherwise stated, the figures in the accompanying drawings do not constitute a scale limitation.

1 is a structural diagram of an ultrasonic transducer according to a first embodiment of the present application;

Fig. 2 is a partial enlarged view of the ultrasonic transducer in Fig. 1;

FIG. 3 is a graph showing the relationship between the enhancement multiple of the emission sensitivity and the contact angle of the ultrasonic transducer according to the first embodiment of the present application;

4 and 5 are structural diagrams of the piezoelectric layer in the ultrasonic transducer according to the first embodiment of the present application;

6 is a schematic diagram of acoustic wave transmission and reception of the ultrasonic transducer according to the first embodiment of the present application;

7 to 9 are structural diagrams of an ultrasonic transducer according to a second embodiment of the present application;

10 and 11 are structural diagrams of the piezoelectric layer in the ultrasonic transducer according to the second embodiment of the present application;

12 is a structural diagram of an ultrasonic transducer according to a third embodiment of the present application;

13 to 16 are structural diagrams of an ultrasonic transducer according to a fourth embodiment of the present application;

FIG. 17 is a structural diagram of an ultrasonic transducer according to a fifth embodiment of the present application.

specific embodiment

In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the embodiments of the present application will be described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application.

When the ultrasonic transducer is applied to a portable mobile terminal, it can be used for fingerprint identification, and its operating frequency is inversely proportional to the thickness of the piezoelectric material. When the piezoelectric ceramic lead zirconate titanate PZT is used as the piezoelectric material, due to its large piezoelectric coefficient, the ultrasonic transducer based on the PZT material has better emission performance; while the piezoelectric coefficient of polyvinylidene fluoride PVDF Therefore, the transmission performance of the PZT ultrasonic transducer is better than that of the PVDF ultrasonic transducer; and the dielectric constant of the PZT material is about 100 times that of the PVDF material, so the receiving performance of the PVDF ultrasonic transducer is better than that of the PZT ultrasonic transducer. device. The loop sensitivity of the ultrasonic transducer is equal to the transmitting sensitivity multiplied by the receiving sensitivity. The ultrasonic transducer used for fingerprint identification usually adopts a working frequency of 10MHz-20MHz. Under the same thickness, the loop sensitivity of the PVDF ultrasonic transducer is greater than that of the PZT ultrasonic transducer. The loop sensitivity of the transducer, so the PVDF ultrasonic transducer is more suitable for portable mobile terminals, but the emission performance of the PVDF ultrasonic transducer is poor, which limits the loop sensitivity of the PVDF ultrasonic transducer. Based on this, the inventor proposes the technical solution of the present application.

The first embodiment of the present application relates to an ultrasonic transducer, which is applied to electronic equipment. The electronic equipment can be a portable mobile terminal, such as a mobile phone, a tablet computer, etc., and the electronic equipment can use the ultrasonic transducer to realize fingerprint recognition and vibration feedback. For example, if the ultrasonic transducer is installed below the touch screen of the electronic device, the ultrasonic transducer can be used for fingerprint recognition under the screen, and can provide vibration feedback when the user uses the electronic device.

In this embodiment, the ultrasonic transducer includes: a first electrode layer, a piezoelectric layer, a second electrode layer and a circuit layer; the piezoelectric layer is provided on the first electrode layer, and the piezoelectric layer is provided with a second electrode layer and a circuit layer. Circuit layer; a plurality of first grooves are formed on the first surface of the piezoelectric layer, each first groove has a concave surface, and the direction of each concave surface is the same as the sound wave emission direction of the ultrasonic transducer, and the concave surface is the same as the piezoelectric The contact angle between the planes on which the first surface of the layer lies is greater than 0 degrees and less than 90 degrees.

Compared with the prior art, this embodiment provides an ultrasonic transducer, which includes: a first electrode layer, a piezoelectric layer, a second electrode layer, and a circuit layer, and the piezoelectric layer is disposed on the first electrode layer The piezoelectric layer is provided with a second electrode layer and a circuit layer, a plurality of first grooves are formed on the first surface of the piezoelectric layer, each first groove has a concave surface, and the orientation of each concave surface is changed with the ultrasonic wave. The sound wave emission direction of the energy device is the same, and the contact angle between the concave surface and the plane where the first surface is located is greater than 0 degrees and less than 90 degrees. When using the ultrasonic transducer to emit sound waves, the concave surface in the piezoelectric layer can converge the sound waves, reducing the divergence angle of the sound wave emission, and the cavity formed by the concave surface forms an acoustic resonance cavity, which can increase the ultrasonic wave. The transmission sensitivity of the transducer improves the loop sensitivity of the ultrasonic transducer; that is, compared with the prior art, higher loop sensitivity can be achieved under the same thickness condition, which is more suitable for portable mobile terminals. In addition, since the transmit sensitivity can be increased, the requirement for transmit bandwidth is reduced under the condition of the same loop sensitivity.

The ultrasonic transducer in this embodiment will be described in detail below, and the details involved are only exemplary descriptions and are not necessary for the present application. The direction of the concave surface of the piezoelectric layer of the ultrasonic transducer is set based on the sound wave emission direction of the ultrasonic transducer. In this embodiment, the sound wave emission direction of the ultrasonic transducer is taken as the direction from the first electrode layer to the circuit layer. Take an example to illustrate.

Please refer to FIG. 1 and FIG. 2 , the ultrasonic transducer includes: a first electrode layer 1 , a piezoelectric layer 2 , a second electrode layer and a circuit layer 4 . Wherein, the first electrode layer 1 and the second electrode layer can be made of materials such as copper, tin, aluminum, or compounds of copper, tin, and aluminum, organic conductive materials, semiconductor materials, and the like.

In one example, the ultrasonic transducer further includes a functional layer 5, and the functional layer 5 may include a substrate and/or a backing; when the ultrasonic transducer emits ultrasonic waves toward the circuit layer 4, the functional layer 5 includes a backing, which can reduce the Backpropagation of ultrasonic waves.

The first electrode layer 1 is arranged on the functional layer 5 , the piezoelectric layer 2 is arranged on the first electrode layer 1 , and the second electrode layer and the circuit layer 4 are arranged on the piezoelectric layer 2 .

A plurality of first grooves are formed on the first surface of the piezoelectric layer 2, each first groove has a concave surface 21, the direction of each concave surface 21 is the same as the sound wave emission direction of the ultrasonic transducer, and the concave surface 21 is connected to The contact angle between the planes on which the first surface of the piezoelectric layer 2 is located is greater than 0 degrees and less than 90 degrees. Wherein, the piezoelectric layer 2 may be a piezoelectric film made of piezoelectric materials such as electrical ceramic lead zirconate titanate PZT, polyvinylidene fluoride PVDF and the like.

In this embodiment, the sound wave emission direction of the ultrasonic transducer is from the first electrode layer 1 to the circuit layer 4. At this time, the concave surface 21 of each first groove of the piezoelectric layer 2 faces the circuit layer 4, so the piezoelectric The first surface of the layer 2 is the upper surface of the piezoelectric layer 2, the upper surface of the piezoelectric layer 2 is in contact with the lower surface of the circuit layer 4, and the concave surface 21 and the plane where the first surface of the piezoelectric layer 2 is located. The contact angle is the contact angle between the concave surface 21 and the lower surface of the circuit layer 4 . The piezoelectric layer 2 includes a second surface opposite to the first surface, and the second surface of the piezoelectric layer 2 is the lower surface of the piezoelectric layer 2 . The second surface of the piezoelectric layer 2 is a flat surface, which is covered on the first electrode layer 1 . This piezoelectric layer 2 is easy to manufacture and is suitable for piezoelectric thin film blade coating technology.

Referring to FIG. 2 , the contact angle between the concave surface 21 and the plane where the first surface of the piezoelectric layer 2 is located is a line L tangent to the concave surface 21 and the circuit layer 4 at the intersection of the concave surface 21 and the lower surface of the circuit layer 4 . The included angle θ between the lower surfaces of the The divergence angle can also make the cavity formed by the concave surface 21 form an acoustic resonance cavity, so as to increase the emission sensitivity of the ultrasonic transducer.

In one example, the contact angle between the concave surface 21 and the plane where the first surface of the piezoelectric layer 2 is located is set between 75 degrees and 90 degrees, so that the concave surface 21 can increase the emission of the ultrasonic transducer as much as possible. sensitivity. Please refer to FIG. 3 , which is a graph showing the relationship between the enhancement multiple of the emission sensitivity of the ultrasonic transducer in FIG. 1 and the included angle θ (that is, the contact angle between the concave surface 21 and the plane on which the first surface is located). When the angle θ is between 0 degrees and 35 degrees, the improvement factor of the emission sensitivity is maintained below 0.5; when the included angle θ is between 35 degrees and 75 degrees, the improvement factor of the transmission sensitivity increases linearly; the included angle θ is 75 degrees. When the angle θ is between 75 degrees and 90 degrees, the enhancement factor of the emission sensitivity remains basically unchanged, and it is in the saturation region of the emission sensitivity improvement. Therefore, when the included angle θ is set between 75 degrees and 90 degrees, the piezoelectric layer 2 can be maximized. increases the transmit sensitivity of the ultrasonic transducer.

It should be noted that, in this embodiment and the following embodiments, the concave surface 21 is taken as an example of a standard spherical surface for description, but the shape of the concave surface 21 is not limited in any way, and the concave surface 21 can be a curved surface, a non-standard spherical surface, etc. , at this time, the piezoelectric layer 2 can still improve the emission sensitivity of the ultrasonic transducer.

In this embodiment, the second electrode layer includes a plurality of first conductive parts 31 , the plurality of first conductive parts 31 are respectively disposed in the first grooves of the piezoelectric layer 2 , and the first conductive parts 31 have distances away from the first electrode layer. The first upper surface of 1, the first upper surface and the first surface of the piezoelectric layer 2 are on the same plane. That is, the second electrode layer is a patterned electrode, which includes a plurality of first conductive parts 31. The first conductive parts 31 match the shapes of the first grooves, so that they can be arranged in the first grooves, and each of the first conductive parts The first upper surface of 31 (ie, the upper surface of the first conductive portion 31 ), the first surface of the piezoelectric layer 2 and the lower surface of the circuit layer 4 are all located on the same plane.

In one example, please refer to FIG. 4 , the first surface of the piezoelectric layer 2 is formed with first grooves arranged in an array and having a hemispherical shape. The second electrode layer includes first conductive parts 31 arranged in an array of hemispherical shapes. The first conductive parts 31 are respectively disposed in the first grooves of the piezoelectric layer 2 . That is, a plurality of hemispherical first grooves arranged in an array are formed on the first surface of the piezoelectric layer 2, which is equivalent to digging a plurality of hemispherical holes in the piezoelectric layer 2. The first conductive portion 31 is a For the hemispherical bumps matching the shape of the first groove, each first conductive portion 31 is disposed in each first groove, and the concave surface 21 of the first groove is a hemispherical surface.

In one example, please refer to FIG. 5 , a plurality of semi-cylindrical first grooves are formed on the first surface of the piezoelectric layer 2 , and the second electrode layer includes semi-cylindrical first conductive parts 31 arranged in parallel , the first conductive parts 31 are respectively arranged in the first grooves of the piezoelectric layer 2 . That is, a plurality of semi-cylindrical first grooves are arranged in parallel on the first surface of the piezoelectric layer 2 , the first conductive parts 31 are semi-cylindrical bodies that match the shape of the first grooves, and each first conductive part 31 is a semi-cylindrical body. It is arranged in each first groove, and the concave surface 21 of the first groove is the inner cylindrical surface of the semi-cylindrical body.

In this embodiment, each first groove can form a piezoelectric unit on the piezoelectric layer 2, that is, the piezoelectric layer 2 includes a plurality of piezoelectric units, and the piezoelectric units can be used to transmit and receive acoustic wave signals. The first electrode layer 1 and the second electrode layer are set to be electrically connected to the circuit layer 4, respectively, the piezoelectric layer 2 is electrically connected to the first electrode layer 1 and the second electrode layer, respectively, and the circuit layer 4 is an electrical connection layer, such as a TFT , CMOS, a PCB board containing wires, etc., which can be used to transmit, process, transmit, and receive signals. For example, the circuit layer 4 can be connected to the processor of the electronic device. After receiving the transmitted ultrasonic signal sent by the processor When instructed, the circuit layer 4 can provide the piezoelectric layer 2 with an AC voltage signal through the first electrode layer 1 and the second electrode layer, and the piezoelectric layer 2 generates a piezoelectric effect to convert the AC voltage signal into the vibration of the piezoelectric layer 2. Thus, ultrasonic waves can be emitted toward the circuit layer 4 along the sound wave emission direction.

Taking the ultrasonic transducer applied to the fingerprint recognition under the screen as an example, please refer to FIG. 6, the ultrasonic transducer is arranged under the touch screen 7, and the circuit layer 4 can be connected to the processor of the electronic device, and after receiving the transmitted ultrasonic wave sent by the processor. When the signal is commanded, the circuit layer 4 can provide an AC voltage signal to the piezoelectric layer 2 through the first electrode layer 1 and the second electrode layer, and the piezoelectric layer 2 generates a piezoelectric effect to convert the AC voltage signal into the piezoelectric layer 2. vibrates, and emits ultrasonic waves 8 toward the touch screen 7 through the piezoelectric unit formed by the first groove. The ultrasonic waves 8 are reflected on the surface of the air and the skin 101 of the finger. Due to the different acoustic impedances of the air and the skin, the reflected ultrasonic signals The intensity of 9 is different. After the piezoelectric layer 2 sends the ultrasonic signal 9 received by the piezoelectric unit to the processor, the processor can generate a fingerprint image according to the ultrasonic signal 9 . The ultrasonic transducer also includes an acoustic impedance matching layer 6, which is arranged between the circuit layer 4 and the touch screen 7, and the acoustic impedance matching layer 6 matches the acoustic impedance of the piezoelectric layer 2, so that the circuit layer 4 and the touch screen can be solved. The problem of mismatch of acoustic resistance between 7, as far as possible to avoid sound waves being reflected on the touch screen 7, to improve the effective sound pressure.

The second embodiment of the present application relates to an ultrasonic transducer. Compared with the first embodiment, the main difference between this embodiment is that another specific structure of the piezoelectric layer is provided.

This embodiment is still described by taking the sound wave emission direction of the ultrasonic transducer as from the first electrode layer 1 to the circuit layer 4 as an example.

Referring to FIG. 7 , a plurality of first grooves are formed on the first surface of the piezoelectric layer 2, and each first groove has a concave surface 21. The piezoelectric layer 2 includes a second surface opposite to the first surface. A plurality of protrusions 22 corresponding to the first grooves are formed on the second surface of the electrical layer 2. The shape of the protrusions 22 may be the same as or different from the shape of the first grooves, and the protrusions 22 and A groove corresponds in position in the direction perpendicular to the piezoelectric layer 2 . The first electrode layer 1 has a second upper surface, the first surface of the piezoelectric layer 2 and the first upper surface of the first conductive part 31 are on the same plane, and the first surface of the piezoelectric layer 2 is on the same plane as the first upper surface of the first conductive part 31 . The second upper surfaces of the electrode layer 1 are not on the same plane.

In this embodiment, the shape of the protruding portion 22 can be the same as the shape of the first groove as an example. In this case, the concave surface 21 and the protruding portion 22 have the same convex surface curvature, and the thickness of the piezoelectric layer 2 can be equal.

In an example, please refer to FIG. 8 , the ultrasonic transducer further includes a plurality of insulating parts 8 , a second groove is formed on the first conductive part 31 , and the plurality of insulating parts 8 are respectively disposed on the first conductive parts 31 of the first conductive part 31 . In the two grooves, each insulating portion 8 is arranged spaced apart from the piezoelectric layer 2 .

In this embodiment, the plurality of insulating parts 8 have a third upper surface away from the first electrode layer 1 , and the third upper surface and the first surface of the piezoelectric layer 2 are on the same plane. The insulating portion 8 is equivalent to an insulating bump disposed on the lower surface of the circuit layer 4 , each of the first conductive portions 31 is respectively disposed in the first groove of the piezoelectric layer 2 , and a second concave is formed on each of the first conductive portions 31 . The shape of the insulating portion 8 matches the shape of the second groove, each insulating portion 8 is respectively arranged in each second groove, and the lower surface of the circuit layer 4 seals each first groove.

In an example, in FIG. 8 , the insulating portion 8 is set to match the acoustic resistance of the piezoelectric layer 2 , that is, the material for the insulating portion 8 is matched to the acoustic resistance of the piezoelectric layer 2 , so as to prevent the acoustic wave from being transmitted in the piezoelectric layer. Excessive reflections are generated between the layer 2 and the second electrode layer and between the second electrode layer and the circuit layer 4 to avoid reducing the emission efficiency. In addition, the insulating portion 8 can be made as thin as possible to further reduce its reflection of sound waves.

In FIG. 7 and FIG. 8 , the second electrode layer is a patterned electrode, the first electrode layer 1 is a whole-surface electrode, the second electrode layer includes a plurality of first conductive parts 31 , and the piezoelectric The unit can be electrically connected to the circuit layer 4 through the first conductive parts 31 therein, and each piezoelectric unit can be individually controlled through the first conductive parts 31; however, it is not limited to this, and a second electrode layer can also be provided For the whole surface electrode, the first electrode layer 1 is a patterned electrode to realize the independent control of each piezoelectric unit, please refer to FIG. 9 , the details are as follows.

The second electrode layer further includes a second electrode body 32 , and a plurality of first conductive parts 31 are formed on the first lower surface of the second electrode body 32 . The first surface is on the same plane, the first electrode layer 1 includes a plurality of first sub-electrodes 11 arranged separately, any two first sub-electrodes 11 are insulated from each other, and the first sub-electrodes 11 are respectively covered on each convex surface. on exit 22. It should be noted that, in the figure, the first sub-electrodes 11 do not contain any substance to achieve insulation, but it is not limited to this, and insulation can also be filled between the first sub-electrodes 11 to achieve insulation.

A plurality of first conductive parts 31 are formed on the second electrode body 32 , each first conductive part 31 on the second electrode body 32 is arranged in each first groove, and a plurality of first conductive parts 31 on the second surface of the piezoelectric layer 2 The protruding parts 22 are respectively located in the first sub-electrodes 11 , that is, an accommodating space is provided on the upper surface of each first sub-electrode 11 , and the protruding parts 22 are respectively arranged in the accommodating space of the first sub-electrodes 11 . The accommodating space of each sub-electrode 11 may completely cover the corresponding protruding portion 22 (as an example in the figure), or may partially cover the corresponding first sub-electrode 11 , so that the pressure on each first groove can be realized. Individual control of electrical units.

10, an array of hemispherical first grooves is formed on the first surface of the piezoelectric layer 2, the second electrode layer includes an array of hemispherical first conductive parts 31, each A conductive portion 31 is respectively disposed in each of the first grooves of the piezoelectric layer 2 , and a plurality of hemispherical protrusions 22 are arranged in a corresponding array on the second surface of the piezoelectric layer 2 .

11, a plurality of semi-cylindrical first grooves are formed on the first surface of the piezoelectric layer 2, and the second electrode layer includes semi-cylindrical first conductive parts 31 arranged in parallel, Each of the first conductive parts 31 is respectively disposed in each of the first grooves of the piezoelectric layer 2 , and a plurality of semi-cylindrical protruding parts 22 are correspondingly disposed in parallel on the second surface of the piezoelectric layer 2 .

The third embodiment of the present application relates to an ultrasonic transducer. Compared with the second embodiment, the main difference between this embodiment is that a piezoelectric layer for separating piezoelectric films is provided.

Please refer to FIG. 12 , the piezoelectric layer 2 includes a plurality of piezoelectric units, each piezoelectric unit includes a second surface opposite to the first surface, and a first groove is formed on the first surface of each piezoelectric unit, The second surface includes a convex surface 23, the first electrode layer 1 has a plurality of accommodation spaces, a plurality of piezoelectric units are arranged in the accommodation spaces of the first electrode layer 1, and a plurality of first conductive parts 31 are respectively arranged in the piezoelectric units. In the first groove, the first electrode layer 1 has a second upper surface, and the first surface of the piezoelectric layer 2, the second upper surface of the first electrode layer 1 and the first upper surface of the first conductive part 31 are in the same on flat surface.

In this embodiment, the piezoelectric layer 2 includes piezoelectric units formed by a plurality of first grooves, and a plurality of accommodation spaces are formed on the first electrode layer 1, and each piezoelectric unit is respectively arranged in each accommodation space, So that there is no contact between any two piezoelectric units, the surface of the first electrode layer 1 provided with the first groove, the first upper surface of the first conductive portion 31 and the lower surface of the circuit layer 4 are on the same plane, With this arrangement, when any piezoelectric unit vibrates, it will not cause interference to adjacent piezoelectric units, thereby avoiding interference between piezoelectric units.

Compared with the second embodiment, the present embodiment provides a piezoelectric layer separating piezoelectric thin films, which can avoid vibration interference among a plurality of piezoelectric units.

The fourth embodiment of the present application relates to an ultrasonic transducer. Compared with the first embodiment, this embodiment is mainly different in that: the first embodiment uses the sound wave emission direction of the ultrasonic transducer as the direction from the first electrode Taking the layer to the circuit layer as an example, in this embodiment, the sound wave emission direction of the ultrasonic transducer is taken as an example from the circuit layer to the first electrode layer for description.

In this embodiment, please refer to FIG. 13 and FIG. 14 , the ultrasonic transducer includes: a first electrode layer 1 , a piezoelectric layer 2 , a second electrode layer and a circuit layer 4 . The first electrode layer 1 and the second electrode layer can be made of materials such as copper, tin, aluminum, or compounds of copper, tin, and aluminum, organic conductive materials, semiconductor materials, and the like.

Exemplarily, the ultrasonic transducer further includes a functional layer 5, and the functional layer 5 is a substrate. In this embodiment, the functional layer 5 can be set to be made of a material that matches the acoustic resistance of the piezoelectric layer 2, that is, the functional layer 5 serves as a substrate. The acoustic resistance matching layer, at this time, the functional layer 5 matches the acoustic resistance of the piezoelectric layer 2, which can improve the effective sound pressure.

The first electrode layer 1 is arranged on the functional layer 5 , the piezoelectric layer 2 is arranged on the first electrode layer 1 , and the second electrode layer and the circuit layer 4 are arranged on the piezoelectric layer 2 .

A plurality of first grooves are formed on the first surface of the piezoelectric layer 2, each first groove has a concave surface 21, the direction of each concave surface 21 is the same as the sound wave emission direction of the ultrasonic transducer, and the concave surface 21 is connected to The contact angle between the planes on which the first surface of the piezoelectric layer 2 is located is greater than 0 degrees and less than 90 degrees. Wherein, the piezoelectric layer 2 may be a piezoelectric film made of piezoelectric materials such as electrical ceramic lead zirconate titanate PZT, polyvinylidene fluoride PVDF and the like.

In this embodiment, the acoustic wave emission direction of the ultrasonic transducer is from the circuit layer 4 to the first electrode layer 1 , and each concave surface 21 faces the first electrode layer 1 at this time, so the first surface of the piezoelectric layer 2 is The lower surface of the piezoelectric layer 2, the contact angle between the concave surface 21 and the plane where the first surface is located is the contact angle between the concave surface 21 and the upper surface of the first electrode layer 1, and the second surface of the piezoelectric layer 2 is the contact angle between the concave surface 21 and the upper surface of the first electrode layer 1. The upper surface of the piezoelectric layer 2 is in contact with the third electrode layer 3 and the circuit layer 4 .

As shown in FIG. 13 , the contact angle between the concave surface 21 and the upper surface of the first electrode layer 1 is a line L tangent to the concave surface 21 at the intersection of the concave surface 21 and the upper surface of the first electrode layer 1 and the first electrode The included angle θ between the upper surfaces of the layers 1 is between 0 degrees and 90 degrees, that is, 0 degrees < θ < 90 degrees, so that the concave surface 21 can converge the sound waves to reduce the sound waves The divergence angle of the emission can also make the cavity formed by the concave surface 21 form an acoustic resonance cavity, so as to increase the emission sensitivity of the ultrasonic transducer.

In this embodiment, the concave surface 21 of the piezoelectric layer 2 faces the first electrode layer. The first electrode layer 1 includes a first electrode body 12 and a plurality of second conductive parts 13 . The first electrode body 12 has a surface close to the piezoelectric layer 2 . On the fourth upper surface, a plurality of second conductive parts 13 are arranged on the fourth upper surface of the first electrode body 12, and a plurality of second conductive parts 13 are respectively arranged in the first grooves of the piezoelectric layer 2, and the first The fourth upper surface of the electrode body 12 , the lower surface of the second conductive portion 13 and the first surface of the piezoelectric layer 2 are on the same plane.

As can be seen from the above, the first electrode layer 1 includes a first electrode body 12 and a plurality of second conductive parts 13 disposed on the fourth upper surface of the first electrode body 12 , and the shapes of the second conductive parts 13 and the first grooves Matching, so that it can be arranged in the first groove, and the third upper surface of the first electrode body 12 can seal the first groove.

In FIG. 13 , a plurality of protrusions 22 corresponding to the first grooves are formed on the second surface of the piezoelectric layer 2 , and the shape of the protrusions 22 may be the same or different from that of the first grooves, and The protruding portion 22 corresponds to the position of the first groove in a direction perpendicular to the piezoelectric layer 2 . The second electrode layer includes a plurality of second sub-electrodes 33. Any two second sub-electrodes 33 are insulated from each other. Between the output portion 22 and the circuit layer 4, and the lower surface of the circuit layer 4 close to the piezoelectric layer 2 and the second surface of the piezoelectric layer are on the same plane. That is to say, the shapes of the second sub-electrodes 33 match the protrusions 22 , and each second sub-electrode 33 covers the corresponding protrusions 22 respectively. The circuit layer 4 is disposed on the piezoelectric layer 2 and covers the piezoelectric layer 2 and the second sub-electrodes 22 . The sub-electrode 33 is formed, and the lower surface of the circuit layer 4 is on the same plane as the second surface of the piezoelectric layer.

In FIG. 14, the second surface of the piezoelectric layer 2 is flat, the second electrode layer includes a plurality of second sub-electrodes 33, any two second sub-electrodes 33 are insulated from each other, and each second sub-electrode 33 is covered on On the second surface of the piezoelectric layer 2, and the position of the second sub-electrodes 33 corresponds to the first groove, that is, each second sub-electrode 33 covers the back of each first groove, and the second sub-electrodes 33 It is located between the second surface of the piezoelectric layer 2 and the lower surface of the circuit layer 4 , and the lower surface of the circuit layer 4 close to the piezoelectric layer 2 is on the same plane as the second surface of the piezoelectric layer 2 .

In FIG. 13 and FIG. 14 , the second electrode layer is a patterned electrode, the first electrode layer 1 is a whole-surface electrode, the second electrode layer includes a plurality of second sub-electrodes 33, and the piezoelectric The unit can be electrically connected to the circuit layer 4 through the corresponding second sub-electrodes 33. At this time, each piezoelectric unit can be individually controlled through each of the second sub-electrodes 33; however, it is not limited to this, and a second electrode layer can also be provided. For the whole surface electrode, the first electrode layer 1 is a patterned electrode to realize the independent control of each piezoelectric unit, please refer to FIG. 15 , the details are as follows.

The second electrode layer 3 covers the second surface of the piezoelectric layer 2 , the first electrode body 12 includes a plurality of third sub-electrodes 121 , any two third sub-electrodes 121 are insulated from each other, and each second conductive portion 13 are formed on the third sub-electrodes 121, respectively. That is, the first electrode body 12 is divided into a plurality of third sub-electrodes 121, a second conductive part 13 is arranged on each third sub-electrode 121, and each second conductive part 13 is located in each first groove, and the third sub-electrode The upper surface of the electrode 121 , the lower surface of the second conductive part 13 and the first surface of the piezoelectric layer 2 are on the same plane, so that the piezoelectric unit formed by each first groove can pass through the second conductive part 13 and the first surface. Each of the third sub-electrodes 121 is electrically connected, so that individual control of the piezoelectric unit formed by each of the first grooves can be realized.

Exemplarily, please refer to FIG. 16 (taking the ultrasonic transducer of FIG. 13 as an example), the ultrasonic transducer further includes a backing layer 10 arranged on the circuit layer 4 , which can reduce the reverse direction of ultrasonic waves in the direction toward the circuit layer 4 . spread.

The fifth embodiment of the present application relates to an ultrasonic transducer. Compared with the fourth embodiment, the main difference between this embodiment is that a piezoelectric layer for separating piezoelectric films is provided.

Referring to FIG. 17 , the concave surface 21 of the first groove of the piezoelectric layer 2 faces the first electrode layer, the first electrode layer 1 includes a plurality of third conductive parts 14 , and the plurality of third conductive parts 14 are respectively disposed on the piezoelectric layer In the first groove of On the same plane; a plurality of first grooves are respectively arranged in the second electrode layer 3 , there is no contact between any two first grooves, and the second electrode layer is provided with the surface of the first groove and the piezoelectric layer 2 The first surfaces of the s are in the same plane.

The piezoelectric layer 2 includes a plurality of first grooves arranged separately, and the plurality of first grooves form a plurality of piezoelectric units of the piezoelectric layer 2, and the plurality of piezoelectric units are arranged in the second electrode layer 3 at intervals, That is, the second electrode layer 3 includes a plurality of accommodating spaces, and each piezoelectric unit is respectively arranged in the accommodating space, so that there is no connection between any two piezoelectric units, so that when any piezoelectric unit vibrates, there is no It will cause interference to adjacent piezoelectric units, avoiding the interference between piezoelectric units.

Compared with the fourth embodiment, this embodiment provides a piezoelectric layer separating piezoelectric thin films, which can avoid vibration interference between piezoelectric units formed by each concave surface.

The sixth embodiment of the present application relates to an electronic device, including the ultrasonic transducer of any one of the first to fifth embodiments. The electronic device may be a portable mobile terminal, such as a mobile phone, a tablet computer, etc. The electronic device may use The ultrasonic transducer realizes functions such as fingerprint recognition and vibration feedback. For example, if the ultrasonic transducer is installed below the touch screen of the electronic device, the ultrasonic transducer can be used for fingerprint recognition under the screen.

Those of ordinary skill in the art can understand that the above-mentioned embodiments are specific embodiments for realizing the present application, and in practical applications, various changes in form and details can be made without departing from the spirit and the spirit of the present application. Scope.

Claims (26)

An ultrasonic transducer, comprising: a first electrode layer, a piezoelectric layer, a second electrode layer and a circuit layer; The piezoelectric layer is arranged on the first electrode layer, and the second electrode layer and the circuit layer are arranged on the piezoelectric layer; A plurality of first grooves are formed on the first surface of the piezoelectric layer, each of the first grooves has a concave surface, and the direction of each of the concave surfaces is the same as the sound wave emission direction of the ultrasonic transducer , the contact angle between the concave surface and the plane on which the first surface is located is greater than 0 degrees and less than 90 degrees. The ultrasonic transducer of claim 1, wherein the concave surface of the first groove of the piezoelectric layer faces the circuit layer, the second electrode layer includes a plurality of first conductive parts, and the A plurality of first conductive parts are respectively disposed in the first grooves of the piezoelectric layer. The ultrasonic transducer of claim 2, wherein the first surface is formed with the first grooves arranged in an array and in a hemispherical shape, and the second electrode layer comprises hemispherical grooves arranged in an array. For the first conductive parts, each of the first conductive parts is respectively disposed in each of the first grooves. The ultrasonic transducer according to claim 2, wherein a plurality of the first grooves in the shape of semi-cylindrical bodies are formed on the first surface, and the second electrode layer comprises semi-cylindrical bodies arranged in parallel Each of the first conductive parts is arranged in each of the first grooves, respectively. The ultrasonic transducer according to any one of claims 2 to 4, wherein the plurality of first conductive parts have a first upper surface away from the first electrode layer, the first upper surface on the same plane as the first surface of the piezoelectric layer. 3. The ultrasonic transducer of claim 2, wherein the piezoelectric layer includes a plurality of piezoelectric cells, each piezoelectric cell includes a second surface opposite the first surface, and each piezoelectric cell includes a second surface opposite the first surface. A first groove is formed on the first surface of the electric unit, the second surface includes a convex surface, the first electrode layer has a plurality of accommodation spaces, and the plurality of piezoelectric units are arranged on the first In the accommodating space of the electrode layer, the plurality of first conductive parts are respectively arranged in the first grooves of the piezoelectric unit. The ultrasonic transducer of claim 6, wherein the first electrode layer has a second upper surface, the first surface of the piezoelectric layer, the second upper surface of the first electrode layer and the first upper surface of the first conductive portion is on the same plane. The ultrasonic transducer of claim 6, wherein the plurality of piezoelectric units are arranged at intervals. The ultrasonic transducer of claim 2, wherein the first electrode layer has a second upper surface, the first surface of the piezoelectric layer and the first upper surface of the first conductive portion On the same plane, the first surface of the piezoelectric layer and the second upper surface of the first electrode layer are not on the same plane. The ultrasonic transducer according to claim 2, characterized in that, the ultrasonic transducer further comprises a plurality of insulating parts, a second groove is formed on the first conductive part, and the insulating parts are arranged on the into the second groove of the first conductive part, so that the insulating part and the piezoelectric layer are spaced apart. 11. The ultrasonic transducer of claim 10, wherein the plurality of insulating parts have a third upper surface away from the first electrode layer, the third upper surface and all the piezoelectric layers The first surfaces are on the same plane. The ultrasonic transducer of claim 1, wherein a concave surface of the first groove of the piezoelectric layer faces the first electrode layer, and the first electrode layer comprises a first electrode body and a plurality of a second conductive part, the first electrode body has a fourth upper surface close to the piezoelectric layer, the plurality of second conductive parts are disposed on the fourth upper surface, and the plurality of second conductive parts The parts are respectively arranged in the first groove of the piezoelectric layer, the fourth upper surface of the first electrode body, the lower surface of the second conductive part, and the first part of the piezoelectric layer. surfaces are in the same plane. 13. The ultrasonic transducer according to claim 12, wherein the first surface of the piezoelectric layer is formed with the first grooves arranged in an array and in a hemispherical shape, and the first electrode layer comprises: The hemispherical second conductive parts are arranged in an array, and each of the second conductive parts is respectively arranged in each of the first grooves of the piezoelectric layer. 13. The ultrasonic transducer of claim 12, wherein a plurality of the first grooves in the shape of a semi-cylindrical are formed on the first surface of the piezoelectric layer, and the first electrode layers include a plurality of first grooves arranged in parallel The semi-cylindrical second conductive parts are respectively arranged in the first grooves of the piezoelectric layer. The ultrasonic transducer of claim 12, wherein the ultrasonic transducer further comprises a backing layer disposed on the circuit layer. 13. The ultrasonic transducer of claim 2 or 12, wherein the piezoelectric layer includes a second surface opposite the first surface, the second surface being flat. The ultrasonic transducer according to claim 2 or 12, wherein the piezoelectric layer comprises a second surface opposite to the first surface, and a plurality of surfaces corresponding to the first surface are formed on the second surface. A protrusion corresponding to the groove. The ultrasonic transducer of claim 17, wherein the second electrode layer further comprises a second electrode body, and the plurality of first conductive parts are formed on a first lower surface of the second electrode body top, the first lower surface and the first surface of the piezoelectric layer are on the same plane; The first electrode layer includes a plurality of first sub-electrodes arranged separately, any two of the first sub-electrodes are insulated from each other, and each of the first sub-electrodes is respectively covered on each of the protruding parts. The ultrasonic transducer according to claim 17, wherein the second electrode layer comprises a plurality of second sub-electrodes, any two of the second sub-electrodes are insulated from each other, and each of the second sub-electrodes is insulated from each other. Electrodes are respectively covered on each of the protruding parts, the second sub-electrode is located between the protruding part and the circuit layer, and the circuit layer is close to the lower surface of the piezoelectric layer and the The second surface of the piezoelectric layer is on the same plane. The ultrasonic transducer of claim 18, wherein the second electrode layer comprises a plurality of second sub-electrodes, any two of the second sub-electrodes are insulated from each other, and each of the second sub-electrodes is insulated from each other. The electrodes are respectively covered on the back of each of the first grooves, the second sub-electrodes are located between the protruding part and the circuit layer, and the circuit layer is close to the lower surface of the piezoelectric layer and the The second surfaces of the piezoelectric layers are on the same plane. The ultrasonic transducer of claim 18, wherein the second electrode layer covers the second surface of the piezoelectric layer; The first electrode body includes a plurality of third sub-electrodes, any two of the third sub-electrodes are insulated from each other, and each of the second conductive parts is formed on each of the third sub-electrodes, respectively. The ultrasonic transducer of claim 1, wherein the concave surface faces the first electrode layer, the first electrode layer includes a plurality of third conductive parts, and the plurality of third conductive parts are respectively arranged in the first groove of the piezoelectric layer; The plurality of third conductive parts have second lower surfaces away from the second electrode layer, and the second lower surfaces of the plurality of third conductive parts and the first surface of the piezoelectric layer are on the same plane superior; A plurality of the first grooves are respectively provided in the second electrode layer, there is no contact between any two of the first grooves, and the second electrode layer is provided with the surface of the first grooves on the same plane as the first surface of the piezoelectric layer. 11. The ultrasonic transducer of claim 10, wherein the insulating portion matches the acoustic resistance of the piezoelectric layer. The ultrasonic transducer of claim 1, wherein the ultrasonic transducer further comprises a functional layer, the first electrode layer is disposed on the functional layer, and the functional layer comprises a substrate and/or or backing. The ultrasonic transducer of claim 1, wherein the contact angle is greater than 75 degrees and less than 90 degrees. An electronic device, comprising: the ultrasonic transducer according to any one of claims 1 to 25.

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