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WO2020259201A1 - 压电传感器及制备方法、进行指纹识别的方法及电子设备 - Google Patents

压电传感器及制备方法、进行指纹识别的方法及电子设备 Download PDF

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Publication number
WO2020259201A1
WO2020259201A1 PCT/CN2020/093190 CN2020093190W WO2020259201A1 WO 2020259201 A1 WO2020259201 A1 WO 2020259201A1 CN 2020093190 W CN2020093190 W CN 2020093190W WO 2020259201 A1 WO2020259201 A1 WO 2020259201A1
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Prior art keywords
piezoelectric
electrode layer
layer
units
electrode
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PCT/CN2020/093190
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English (en)
French (fr)
Inventor
李秀锋
刘英明
郭玉珍
张晨阳
Original Assignee
京东方科技集团股份有限公司
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Priority to US17/264,912 priority Critical patent/US12016249B2/en
Publication of WO2020259201A1 publication Critical patent/WO2020259201A1/zh

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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
    • G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
    • G06V40/12—Fingerprints or palmprints
    • G06V40/13—Sensors therefor
    • G06V40/1306—Sensors therefor non-optical, e.g. ultrasonic or capacitive sensing
    • 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
    • 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
    • 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
    • H10N30/30—Piezoelectric or electrostrictive devices with mechanical input and electrical output, e.g. functioning as generators or sensors
    • H10N30/302—Sensors
    • 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
    • H10N30/704—Piezoelectric or electrostrictive devices based on piezoelectric or electrostrictive films or coatings
    • H10N30/706—Piezoelectric or electrostrictive devices based on piezoelectric or electrostrictive films or coatings characterised by the underlying bases, e.g. substrates
    • H10N30/708—Intermediate layers, e.g. barrier, adhesion or growth control buffer layers
    • 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
    • H10N30/80—Constructional details
    • 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
    • H10N30/80—Constructional details
    • H10N30/87—Electrodes or interconnections, e.g. leads or terminals
    • 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
    • H10N30/80—Constructional details
    • H10N30/87—Electrodes or interconnections, e.g. leads or terminals
    • H10N30/871—Single-layered electrodes of multilayer piezoelectric or electrostrictive devices, e.g. internal electrodes

Definitions

  • the embodiments of the present disclosure relate to piezoelectric sensors and manufacturing methods, methods for fingerprint recognition, and electronic equipment.
  • the working principle of the piezoelectric sensor is to use the inverse piezoelectric effect of the piezoelectric material (such as acting as a transmitter) (applying an alternating voltage in a specific direction to vibrate the piezoelectric material) to emit a specific frequency of ultrasonic waves, which are due to contact during the propagation process.
  • the object to be measured undergoes energy attenuation or phase change, and when it reaches the piezoelectric material serving as a receiver, a positive piezoelectric effect (electric charge is generated under the pressure of ultrasonic waves) occurs, so as to determine the energy or phase change of the ultrasonic waves to achieve sensing detection.
  • piezoelectric sensors can be used to make judgments on the physical environment in the ultrasonic propagation path, such as fingerprint recognition, touch switches, pressure sensors, imaging of human internal organs, and metal product flaw detection.
  • biometric recognition such as fingerprint recognition
  • piezoelectric sensors have the advantages of anti-interference, multi-dimensional imaging, and easy integration compared to other technical means (capacitive, optical, etc.).
  • At least one embodiment of the present disclosure provides a piezoelectric sensor, which includes:
  • a first electrode layer and a second electrode layer disposed oppositely;
  • the piezoelectric layer is between the first electrode layer and the second electrode layer and includes a plurality of piezoelectric units arranged at intervals and an insulating layer between adjacent piezoelectric units,
  • the first electrode layer includes a plurality of sub-electrodes corresponding to the plurality of piezoelectric units;
  • the second electrode layer includes a plurality of sub-electrodes corresponding to the plurality of piezoelectric units;
  • Each of the first electrode layer and the second electrode layer includes a plurality of sub-electrodes corresponding to the plurality of piezoelectric units.
  • the plurality of piezoelectric units are arranged in an array, and the plurality of sub-electrodes are in one-to-one correspondence with the plurality of piezoelectric units.
  • the Young's modulus of the material constituting the insulating layer is smaller than the Young's modulus of the material constituting the piezoelectric unit.
  • the Young's modulus of the material constituting the insulating layer is not greater than 2 GPa.
  • the piezoelectric sensor further includes an insulating structure, wherein the insulating structure is between the adjacent sub-electrodes.
  • one of the first electrode layer and the second electrode layer is a planar electrode
  • the other of the first electrode layer and the second electrode layer includes the The plurality of sub-electrodes corresponding to the plurality of piezoelectric units.
  • the piezoelectric sensor further includes an auxiliary layer, the auxiliary layer being located at at least one of the following positions:
  • the piezoelectric sensor further includes at least one of the following:
  • An excitation source which is electrically connected to the first electrode layer and the second electrode layer to excite a plurality of piezoelectric units to generate ultrasonic waves;
  • a phase controller which is electrically connected to the first electrode layer and the second electrode layer, and is configured to individually modulate the phase of a signal used to excite each piezoelectric unit to generate ultrasonic waves.
  • the piezoelectric sensor further includes a piezoelectric sensing circuit including a storage capacitor, a first transistor, a second transistor, a third transistor, and a fourth transistor,
  • the control electrode of the first transistor is configured to receive a sampling control signal, and the first electrode of the first transistor is connected to be configured to receive a bias signal,
  • the second electrode layer, the second electrode of the first transistor, the first end of the storage capacitor, and the control electrode of the second transistor are connected to a first node
  • the second end of the storage capacitor is connected to the first power supply voltage
  • the second electrode of the second transistor is connected to the first power supply voltage, and the first electrode of the second transistor, the second electrode of the third transistor, and the first electrode of the fourth transistor are connected to the Two nodes,
  • the control electrode of the third transistor and the first electrode of the third transistor are configured to receive a second power supply voltage
  • the second pole of the fourth transistor serves as a signal output terminal of the signal reading circuit, and the control pole of the fourth transistor is configured to receive an output control signal.
  • the piezoelectric sensor further includes a substrate, wherein the substrate is on a side of the first electrode layer away from the piezoelectric layer.
  • At least one embodiment of the present disclosure proposes a method for fingerprint identification. According to an embodiment of the present disclosure, the method includes:
  • an excitation source to excite a piezoelectric sensor to generate ultrasonic waves, wherein the piezoelectric sensor includes:
  • a first electrode layer and a second electrode layer disposed oppositely;
  • the piezoelectric layer is located between the first electrode layer and the second electrode layer and includes a plurality of piezoelectric units arranged at intervals and an insulating layer between adjacent piezoelectric units,
  • the first electrode layer includes a plurality of sub-electrodes corresponding to the plurality of piezoelectric units;
  • the second electrode layer includes a plurality of sub-electrodes corresponding to the plurality of piezoelectric units;
  • Each of the first electrode layer and the second electrode layer includes a plurality of sub-electrodes corresponding to the plurality of piezoelectric units, and
  • the piezoelectric sensor receives the ultrasonic wave reflected by the finger and converts the received ultrasonic wave into an electric signal, thereby realizing fingerprint recognition.
  • the piezoelectric sensor further includes a phase controller that is electrically connected to the first electrode layer and the second electrode layer, and
  • the phase controller is used to individually modulate the phase of the signal used to excite each piezoelectric unit to generate ultrasonic waves.
  • the individually modulating the phase of the signal used to excite each piezoelectric unit to generate ultrasonic waves includes: adjusting the phase of the signal applied to the plurality of piezoelectric units so that the plurality of piezoelectric units The ultrasonic signal generated by the piezoelectric unit has a maximum amplitude at a set position.
  • the method further includes: changing the direction of the maximum amplitude formed by adjusting the phases of the signals applied to the plurality of piezoelectric units, so that the direction of the maximum amplitude can be along The scheduled route is changed.
  • the method further includes: using the piezoelectric sensing circuit in the piezoelectric sensor to convert the electrical signals converted by the plurality of piezoelectric units from AC signals to DC signals, and store them separately In the storage capacitor of the piezoelectric sensor circuit, it is sequentially output to the peripheral signal processor in the signal readout stage.
  • At least one embodiment of the present disclosure also proposes a method for preparing a piezoelectric sensor according to any embodiment of the present disclosure. According to an embodiment of the present disclosure, the method includes:
  • the first electrode layer includes a plurality of sub-electrodes corresponding to the plurality of piezoelectric units;
  • the second electrode layer includes a plurality of sub-electrodes corresponding to the plurality of piezoelectric units;
  • Each of the first electrode layer and the second electrode layer includes a plurality of sub-electrodes corresponding to the plurality of piezoelectric units.
  • the method before forming the second electrode layer on the substrate, the method further includes: forming a piezoelectric sensor circuit on the substrate, wherein the piezoelectric sensor circuit is positioned on the first Between the two electrode layers and the substrate, and the second electrode layer includes a plurality of sub-electrodes corresponding to the plurality of piezoelectric units, and the plurality of sub-electrodes arranged at intervals are formed on the second electrode layer.
  • the piezoelectric unit and the insulating layer located between the adjacent piezoelectric units include: spin-coating a polyvinylidene fluoride film on the side of the plurality of sub-electrodes away from the substrate, and using the polyvinylidene fluoride film
  • the vinylidene fluoride film forms a plurality of the piezoelectric units arranged in an array, and the insulating layer is formed at the gap between the adjacent piezoelectric units.
  • the method further includes: providing a substrate on a side of the first electrode layer away from the piezoelectric layer.
  • At least one embodiment of the present disclosure also proposes an electronic device.
  • the electronic device includes: a piezoelectric sensor according to any embodiment of the present disclosure.
  • the electronic device further includes a display screen, and the piezoelectric sensor is provided on a side of the display screen facing away from the light-emitting side.
  • the electronic device further includes a cover plate, wherein the cover plate is on the side of the display screen away from the piezoelectric sensor and the thickness of the cover plate is 50 micrometers to 200 micrometers.
  • Fig. 1A shows a schematic cross-sectional structure diagram of a piezoelectric sensor according to at least one embodiment of the present disclosure
  • FIG. 1B shows a schematic cross-sectional structure diagram of a piezoelectric sensor according to at least one embodiment of the present disclosure
  • FIG. 1C shows a schematic cross-sectional structure diagram of a piezoelectric sensor according to at least one embodiment of the present disclosure
  • Fig. 2 shows a schematic top view of a piezoelectric layer according to at least one embodiment of the present disclosure
  • FIG. 3A shows a schematic cross-sectional structure diagram of a piezoelectric sensor according to another embodiment of the present disclosure
  • 3B shows a schematic cross-sectional structure diagram of a piezoelectric sensor according to another embodiment of the present disclosure
  • FIG. 4 shows a schematic diagram of the principle of fingerprint recognition using a piezoelectric sensor according to at least one embodiment of the present disclosure
  • Fig. 5 shows a schematic diagram of the principle of sensing using a piezoelectric sensor according to at least one embodiment of the present disclosure
  • Fig. 6 shows a schematic diagram of sensing by using a piezoelectric sensor according to another embodiment of the present disclosure
  • Fig. 7 shows a schematic diagram of a partial circuit structure of a piezoelectric sensor according to at least one embodiment of the present disclosure
  • FIG. 8 shows a schematic cross-sectional structure diagram of a piezoelectric sensor according to another embodiment of the present disclosure
  • FIG. 9 is a schematic structural diagram of a piezoelectric sensing circuit according to at least one embodiment of the present disclosure.
  • FIG. 10 shows a flowchart of a method for fingerprint identification according to at least one embodiment of the present disclosure
  • FIG. 11 shows a flowchart of a method for fingerprint identification according to another embodiment of the present disclosure.
  • FIG. 12 is a timing diagram of a piezoelectric sensing circuit according to at least one embodiment of the present disclosure.
  • FIG. 13 shows a flowchart of a method for preparing a piezoelectric sensor according to at least one embodiment of the present disclosure
  • Figure 14 shows a flow chart of a method for preparing a piezoelectric sensor according to another embodiment of the present disclosure
  • FIG. 15 shows a schematic structural diagram of an electronic device according to at least one embodiment of the present disclosure.
  • Fig. 16 shows a schematic structural diagram of an electronic device according to another embodiment of the present disclosure.
  • the present disclosure proposes a piezoelectric sensor.
  • the piezoelectric sensor 1000 includes relatively disposed The substrate 100, the contact layer 300, and the piezoelectric structure 200 located between the substrate 100 and the contact layer 300.
  • the piezoelectric structure 200 includes: a first electrode layer 210 located on the side of the substrate 100 facing the contact layer 300, a piezoelectric layer 230 located on the side of the first electrode layer 210 away from the substrate 100, and a piezoelectric layer 200 located far away
  • the second electrode layer 220 on the side of the substrate 100 and the piezoelectric layer 230 include a plurality of piezoelectric cells 10 arranged at intervals, and an insulating layer 20 between adjacent piezoelectric cells 10.
  • the first electrode layer 210 and/or the second electrode layer 220 that is, at least one of the first electrode layer 210 and the second electrode layer 220, includes a plurality of sub-electrodes corresponding to the piezoelectric unit 10 (for example, refer to FIG. 1A).
  • the second electrode layer 220 includes at least one sub-electrode 221 corresponding to the piezoelectric unit 10).
  • a plurality of piezoelectric units 10 arranged at intervals can independently transmit/receive signals, and can focus and control the direction of the ultrasonic signal emitted by the entire piezoelectric structure 200, improve the signal strength and resolution, and increase
  • the area of the monitoring area reduces the area occupied by the piezoelectric sensor and improves the efficiency of human-computer interaction.
  • the piezoelectric sensor 1000 is described as including the contact layer 300.
  • the contact layer 300 refers to the combination of the piezoelectric sensor 1000 in actual use.
  • other functional film layers located on the side of the piezoelectric structure 200 close to the user.
  • the display screen is the contact layer 300.
  • the first electrode layer 210, the second electrode layer 220, and the piezoelectric layer 230 described above can be used as a transmitter and a receiver at the same time, that is, through different In the working sequence, the same piezoelectric layer 230 is used to realize the transmission of ultrasonic signals, and the process of receiving the reflected ultrasonic signals and converting them into electrical signals.
  • the piezoelectric materials and electrodes that constitute the piezoelectric sensor are usually integrated under the display screen of the electronic device, and then can be used in the entire display screen. Realize a larger area of fingerprint recognition.
  • the piezoelectric material and electrodes are all arranged in a whole layer, and when the whole layer of piezoelectric material transmits or receives signals, the signal is prone to crosstalk, and energy is easily dissipated, resulting in signal Attenuation, thereby reducing the signal resolution, weakening the discrimination of the target (such as fingerprint) to be identified, and reducing the sensitivity and accuracy of fingerprint identification.
  • the piezoelectric layer ie, piezoelectric material layer
  • the piezoelectric layer includes a plurality of piezoelectric units arranged at intervals
  • the plurality of piezoelectric units arranged at intervals can be independently Transmit/receive signals, that is, multiple piezoelectric units can form multiple independent piezoelectric sensor subunits. Therefore, it is possible to focus and control the direction of the ultrasonic signal emitted by the entire piezoelectric layer by independently adjusting the signal emission of each piezoelectric unit. For example, the signals emitted by multiple piezoelectric units can interfere, etc.
  • the ultrasonic signal can obtain the maximum amplitude at a specific position, which can increase the signal strength and the resolution of the piezoelectric sensor, and obtain an effect similar to converging the ultrasonic signal in a specific direction, thereby increasing the area of the monitoring area, such as the aforementioned
  • the piezoelectric sensor can be set only in a part of the area below the display screen to realize fingerprint recognition on the entire display screen, which reduces the area occupied by the piezoelectric sensor and improves Human-computer interaction efficiency.
  • the position of the maximum amplitude can also be changed to realize scanning signal sensing.
  • the gap between the piezoelectric units needs to be filled with an insulating layer to ensure the The electrode structure can obtain sufficient mechanical support.
  • the insulating layer 20 can also isolate adjacent piezoelectric units from each other when transmitting/receiving signals, thereby reducing the electrical coupling between adjacent piezoelectric units when transmitting/receiving signals, that is, reducing The signal crosstalk of the piezoelectric layer when transmitting/receiving signals improves the resolution of the piezoelectric sensor.
  • the specific type of the substrate 100 is not particularly limited.
  • the substrate 100 may be formed of an insulating material, such as epoxy resin.
  • the substrate 100 may include a protective sub-layer 110 and an acoustic wave reflection sub-layer 120 disposed oppositely, wherein the acoustic wave reflection sub-layer 120 may be disposed toward the piezoelectric structure 200.
  • the protective sublayer 110 may be formed of an insulating material, such as epoxy resin.
  • the acoustic wave reflection sublayer 120 can reflect the ultrasonic signal transmitted to one side of the substrate 100 to the other side, reducing signal attenuation, and further improving signal strength and sensitivity.
  • the acoustic wave reflection sub-layer 120 may be formed of metal.
  • the material forming the acoustic wave reflection sub-layer 120 may include copper; specifically, the thickness of the acoustic wave reflection sub-layer 120 may be 10-100 ⁇ m, for example, 20 ⁇ m. It is 50 ⁇ m, and may be 80 ⁇ m or the like. Therefore, when the thickness of the acoustic wave reflection sublayer 120 is in this range, the ultrasonic signal transmitted to the substrate 100 side can be better reflected.
  • the piezoelectric structure 200 includes a first electrode layer 210, a second electrode layer 220, and a piezoelectric layer 230. Specifically, a good electrical connection can be formed between the first electrode layer 210 and the piezoelectric layer 230, and between the second electrode layer 220 and the piezoelectric layer 230.
  • an AC voltage can be applied to the piezoelectric layer 230, for example, a 10-20MHz ⁇ 50V short-time sine or square wave, sawtooth wave signal
  • the piezoelectric layer 230 is driven by the voltage signal to emit ultrasonic waves; in the signal receiving stage, the reflected ultrasonic waves can be transmitted to the piezoelectric layer 230, and the piezoelectric layer 230 converts the sound pressure into an electrical signal and transmits it To the receiving electrode (for example, on the second electrode layer 220).
  • At least one of the first electrode layer 210 and the second electrode layer 220 includes a plurality of sub-electrodes corresponding to the piezoelectric unit 10.
  • the first electrode layer 210 is an entire layer of electrodes
  • the second electrode layer 220 may include a plurality of sub-electrodes 221 corresponding to the piezoelectric unit 10, or referring to FIG. 1B, the second electrode layer 220 may include The electric unit 10 corresponds to a plurality of sub-electrodes 221, and the first electrode layer 210 may include a plurality of sub-electrodes 211 corresponding to the piezoelectric unit 10, or as shown in FIG.
  • the first electrode layer 210 may include a plurality of For the sub-electrodes 211 corresponding to the unit 10, the second electrode layer 220 may be an entire layer of electrodes.
  • the material forming the first electrode layer 210 is not particularly limited. For example, it may include silver; specifically, the thickness of the first electrode layer 210 may be 6-12 ⁇ m, for example, 8 ⁇ m, 10 ⁇ m, etc., thereby further improving The performance of the piezoelectric sensor.
  • Those skilled in the art can understand that at least one of the first electrode layer 210 and the second electrode layer 220 includes a plurality of sub-electrodes, so as to realize the application of individually controllable voltage signals to the plurality of piezoelectric units. Therefore, as long as one of the first electrode layer 210 and the second electrode layer 220 has a plurality of independent sub-electrodes.
  • the first electrode layer 210 is an entire layer of electrodes and the second electrode layer 220 includes a plurality of sub-electrodes 221 as examples to describe various embodiments of the present disclosure. However, it should be understood that the embodiments of the present disclosure are not limited thereto.
  • the piezoelectric sensor 1000 may further include an auxiliary layer 240, which may be disposed between the first electrode layer 210 and the piezoelectric layer 230, whereby the auxiliary layer 240 not only
  • the adhesion between the first electrode layer 210 and the piezoelectric layer 230 can be enhanced, and the metal atoms (eg, Ag, Cu, etc.) in the first electrode layer 210 and the acoustic wave reflection sublayer 120 can be prevented from diffusing to the piezoelectric unit 10
  • This further affects the performance of the piezoelectric unit 10 and the like, and can increase the breakdown voltage of the piezoelectric structure 200.
  • the material forming the auxiliary layer 240 may include molybdenum, chromium, platinum, etc., the thickness of the auxiliary layer 240 may be 50-100 nm, etc., and the total thickness of the auxiliary layer 240 and the first electrode layer 210 may be about 10 ⁇ m.
  • the auxiliary layer 240 when the first electrode layer 210 is a whole-layer structure, the auxiliary layer 240 may also be a whole-layer structure; when the first electrode layer 210 includes a plurality of sub-electrodes, that is, the first electrode layer 210 is a pattern When the structure is formed, the auxiliary layer 240 may also have the same patterned structure as the first electrode layer 210.
  • the first electrode layer 210 and the auxiliary layer 240 in a laminated structure can be formed first, and then through a patterning process, the first electrode layer 210 and the auxiliary layer 240 is patterned to form a structure with a plurality of sub-electrodes arranged at intervals.
  • the piezoelectric sensor 1000 may further include an auxiliary layer 241.
  • the auxiliary layer 241 may be disposed between the second electrode layer 220 and the piezoelectric layer 230.
  • the auxiliary layer 241 may not only The adhesion between the second electrode layer 220 and the piezoelectric layer 230 is enhanced, and in the case where the second electrode layer 220 is formed by metal, metal atoms (eg, Ag, Cu, etc.) in the second electrode layer 220 can be prevented Diffusion to the piezoelectric unit 10 affects the performance of the piezoelectric unit 10 and the like, and can increase the breakdown voltage of the piezoelectric structure 200.
  • the material forming the auxiliary layer 241 may include molybdenum, chromium, platinum, etc., and the thickness of the auxiliary layer 241 may be 50-100 nm or the like.
  • the auxiliary layer 241 when the second electrode layer 220 has a whole layer structure, the auxiliary layer 241 may also have a whole layer structure; when the second electrode layer 220 includes a plurality of sub-electrodes, that is, the second electrode layer 220 has a pattern When the structure is formed, the auxiliary layer 241 may also have the same patterned structure as the second electrode layer 220.
  • the second electrode layer 220 and the auxiliary layer 241 of a laminated structure can be formed first, and then through a patterning process, the second electrode layer 220 and the auxiliary layer 241 is patterned to form a structure with a plurality of sub-electrodes arranged at intervals.
  • the second electrode layer 220 may include a plurality of sub-electrodes 221, and the plurality of sub-electrodes 221 may be arranged in a one-to-one correspondence with the plurality of piezoelectric units 10.
  • the number of the sub-electrodes 221 corresponds to the number of piezoelectric units 10 Can be equal.
  • the material forming the sub-electrode 221 is not particularly limited, and may include, for example, indium tin oxide (ITO) or the like.
  • ITO indium tin oxide
  • the piezoelectric layer 230 may include a plurality of piezoelectric units 10 arranged in an array.
  • the piezoelectric unit 10 may be formed of a piezoelectric material.
  • the material forming the piezoelectric unit 10 may include polyvinylidene fluoride (PVDF), lead zirconate titanate piezoelectric ceramics (PZT), aluminum nitride (AlN )Wait.
  • the thickness of the piezoelectric unit 10 can be 5-50 ⁇ m, for example, it can be 10 ⁇ m, it can be 20 ⁇ m, it can be 30 ⁇ m, it can be 40 ⁇ m, etc. When the thickness of the piezoelectric unit 10 is in this range, it can emit and Receive ultrasonic signals.
  • the Young's modulus of the material constituting the insulating layer 20 may be smaller than the Young's modulus of the material constituting the piezoelectric unit 10.
  • the insulating layer 20 is softer than the piezoelectric unit 10, and the pressure acting on the piezoelectric layer 230 for generating the positive piezoelectric effect (that is, the piezoelectric material generates electric charge under pressure) can be concentrated on the piezoelectric On the unit 10, the sound pressure sensed by a single piezoelectric unit 10 can be increased, thereby increasing the signal strength, and will not affect the piezoelectric characteristics of the piezoelectric unit 10 itself, such as piezoelectric coefficient D 33 , dielectric constant, etc.
  • the insulating layer 20 can further divide the plurality of piezoelectric units 10 to reduce signal crosstalk and energy loss caused by electrical coupling and mechanical vibration coupling between adjacent piezoelectric units 10, thereby further improving the piezoelectric sensor 1000 resolution and sensitivity.
  • the piezoelectric layer 230 may include an array of M rows and N columns of piezoelectric cells 10, and the size of each piezoelectric cell 10 may be a ⁇ a (and each The size of the sub-electrodes 221 corresponding to each piezoelectric unit 10 is also a ⁇ a), the distance between two adjacent piezoelectric units 10 in each row can be b, and the distance between two adjacent rows of piezoelectric units 10 The spacing between can be b.
  • the piezoelectric layer 230 can receive the ultrasonic signal reflected by the object to be detected.
  • the ultrasonic signals received at different positions of the piezoelectric layer 230 are also different.
  • the insulating layer 20 in the sub-unit 231 is formed of a material with a larger Young's modulus (harder)
  • the insulating layer 20 is formed of a softer material (the Young's modulus of the insulating layer material is smaller than the Young's modulus of the piezoelectric unit material).
  • the Young's modulus of the material constituting the insulating layer 20 may not be greater than 2 GPa, for example, may be 1 MPa-2 GPa.
  • the performance of the piezoelectric sensor can be further improved.
  • the material constituting the insulating layer 20 may include cured epoxy photosensitive glue, liquid optical transparent glue, polydimethylsiloxane (PDMS), and the like.
  • the specific type of the contact layer 300 is not particularly limited, for example, it may be a glass substrate, a display screen, or the like.
  • the Young's modulus of the material forming the contact layer 300 may be greater than the Young's modulus of the material forming the piezoelectric unit 10, that is, the contact layer 300 may be harder.
  • the piezoelectric sensor 1000 may further include an excitation source 400 that is electrically connected to the piezoelectric structure to excite a plurality of piezoelectric units 20 to generate ultrasonic waves.
  • the excitation source 400 can be electrically connected to the first electrode layer 210 and the second electrode layer 220.
  • the excitation source 400 can pass through the first electrode layer 210 and the second electrode layer 220 (a plurality of and piezoelectric unit 10 Electrically connected sub-electrodes), apply AC voltage to each piezoelectric unit 10, for example, apply a short-time sine or square wave, sawtooth wave signal of 10-20MHz ⁇ 50V, etc.
  • the piezoelectric unit 10 is driven by the voltage signal, The ultrasonic waves are respectively emitted, and the ultrasonic waves emitted by the plurality of piezoelectric units 10 can be synthesized into an approximate plane wave after propagating for a certain distance.
  • the Young’s modulus of the insulating layer 20 between the plurality of piezoelectric elements 10 is small, there is no mechanical coupling loss between the plurality of piezoelectric elements 10, therefore, energy dissipation can be reduced and the The intensity of the synthesized plane wave finally emitted by the piezoelectric structure is improved, and the signal intensity and monitoring sensitivity are improved.
  • the piezoelectric sensor 1000 may further include a phase controller 600.
  • the phase controller 600 may be electrically connected to the piezoelectric structure, and may be individually modulated to excite each piezoelectric unit 10 to generate ultrasonic waves. The phase of the signal.
  • the ultrasonic signals emitted by each piezoelectric unit 10 can be individually adjusted (for example, excitation signals with different time delays can be applied to different piezoelectric units 10), and multiple piezoelectric units can emit
  • the phases of the ultrasonic signals can be the same or different (refer to FIG.
  • the piezoelectric sensor described above when used for fingerprint recognition of electronic devices, the piezoelectric sensor can be set only in a part of the area below the display screen to realize fingerprint recognition on the entire display screen, reducing the occupation of the piezoelectric sensor The area improves the efficiency of human-computer interaction and further improves the performance of the piezoelectric sensor.
  • the piezoelectric sensor 1000 may further include a piezoelectric sensing circuit 500, and the piezoelectric sensing circuit 500 is electrically connected to the piezoelectric structure.
  • the piezoelectric sensor circuit 500 may correspond to a piezoelectric structure, for example. Therefore, in the signal receiving stage, using the piezoelectric sensor circuit 500, the piezoelectric layer 230 receives the reflected wave and converts the generated electrical signal and outputs it to the peripheral signal processor, so as to monitor the piezoelectric sensor 1000 The results are analyzed and judged.
  • the piezoelectric sensing circuit 500 can convert the electrical signals converted by the plurality of piezoelectric units 10 from AC signals to DC signals, respectively, and store them in the storage capacitors of the piezoelectric sensing circuit 500, and in the signal readout stage Output to the peripheral signal processor in turn.
  • the piezoelectric sensing circuit 500 may be provided with a side of the second electrode layer 220 away from the first electrode layer 210.
  • the piezoelectric sensing circuit 500 may include a control and emission circuit, a detection circuit (not shown in the figure), a TFT circuit, and the like.
  • the aforementioned excitation source and phase sensor can control the AC voltage applied between the first electrode layer and the second electrode layer through the control and emission circuit, and then can control the phase of the ultrasonic signal emitted by each piezoelectric unit.
  • the detection circuit and the TFT circuit can output the electrical signal generated by each piezoelectric unit to the peripheral signal processor in a certain order after receiving the reflected wave and converting it.
  • FIG. 9 is a schematic structural diagram of a piezoelectric sensing circuit 500 according to at least one embodiment of the present disclosure.
  • the piezoelectric sensing circuit 500 includes a storage capacitor Cg, a first transistor M1, and a signal reading circuit.
  • the control electrode of the first transistor M1 is configured to receive the sampling control signal Vrst, and the first electrode of the first transistor M1 is configured to receive the bias signal Vbias.
  • the second electrode layer 220, the second electrode of the first transistor M1, the first terminal of the storage capacitor Cg, and the first terminal of the signal reading circuit are connected to the first node N1.
  • the second end of the storage capacitor Cg is connected to the first power supply voltage Vss.
  • the signal reading unit is configured to read the electrical signal stored in the storage capacitor Cg, that is, the voltage signal received by the second electrode layer 220.
  • the signal reading circuit may include a second transistor M2, a third transistor M3, and a fourth transistor M4.
  • the control electrode of the second transistor M2 serves as the first end of the signal reading circuit, the second electrode of the second transistor M2 is connected to the first power supply voltage Vss, the first electrode of the second transistor M2, the second electrode of the third transistor M3 And the first pole of the fourth transistor M4 is connected to the second node N2.
  • the control electrode of the third transistor M3 and the first electrode of the third transistor M3 are configured to receive the second power supply voltage Vdd.
  • the second electrode of the fourth transistor M4 serves as the signal output terminal Vout of the signal reading circuit, and the control electrode of the fourth transistor M4 is configured to receive the output control signal Vsel.
  • the second power supply voltage Vdd is higher than the first power supply voltage Vss.
  • the first power supply voltage Vss is, for example, a low voltage, such as ground, and the second power supply voltage is, for example, a constant high voltage.
  • the signal reading circuit may have other structures, as long as the signal reading circuit can read the storage capacitor Cg.
  • the stored electrical signal is not limited by the embodiment of the present disclosure.
  • the transistors used in the embodiments of the present disclosure may all be thin film transistors or field effect transistors or other switching devices with the same characteristics.
  • the source and drain of the transistor used here can be symmetrical in structure, so the source and drain can be structurally indistinguishable.
  • the aforementioned transistors may all be N-type transistors, the first electrode may be the drain, and the second electrode may be the source.
  • the piezoelectric sensor of the embodiment of the present disclosure by arranging a plurality of piezoelectric units distributed at intervals, the plurality of piezoelectric units arranged at intervals can transmit/receive signals independently, which reduces the transmission/reception of the piezoelectric structure.
  • the electrical coupling during the signal reduces the signal crosstalk, and can focus and control the direction of the ultrasonic signal emitted by the entire piezoelectric structure, which can further improve the signal strength and resolution, and can increase the area of the monitoring area and reduce the pressure.
  • the occupied area of the electric sensor improves the efficiency of human-computer interaction.
  • the present disclosure proposes a method for fingerprint recognition.
  • the method can use any of the piezoelectric sensors described above for fingerprint recognition. Therefore, the method has all the features and advantages of the piezoelectric sensors described above. Repeat it again.
  • the method includes:
  • S100 Use an excitation source to excite the voltage sensor to generate ultrasonic waves.
  • the voltage sensor has the same structure as any one of the voltage sensors described above.
  • the piezoelectric sensor includes a first electrode layer, a second electrode layer and a piezoelectric layer that are arranged oppositely.
  • the piezoelectric layer is located between the first electrode layer and the second electrode layer and includes a plurality of piezoelectric units arranged at intervals and an insulating layer between adjacent piezoelectric units.
  • At least one of the first electrode layer and the second electrode layer includes a plurality of sub-electrodes corresponding to the piezoelectric unit.
  • the excitation source can be electrically connected to the first electrode layer and the second electrode layer, and the excitation source can pass through the first electrode layer and the second electrode layer (a plurality of sub-electrodes electrically connected to the piezoelectric unit),
  • An AC voltage is applied to each piezoelectric unit, such as a short-time sine or square wave, sawtooth wave signal of 10-20MHz ⁇ 50V, etc.
  • the piezoelectric unit is driven by the voltage signal, and respectively emits ultrasonic waves.
  • the ultrasonic waves emitted by the electric unit can be synthesized into an approximate plane wave after propagating a certain distance.
  • the piezoelectric sensor may further include a phase controller, which is electrically connected to the piezoelectric structure, and the phase of the signal used to excite each piezoelectric unit to generate ultrasonic waves can be individually modulated by the phase controller. Therefore, the signal emitted by each piezoelectric unit can be individually adjusted through the phase controller, which is beneficial to focus and direction control of the signal emitted by the entire piezoelectric structure, and further improves the resolution of fingerprint recognition using this method. rate.
  • a phase controller which is electrically connected to the piezoelectric structure, and the phase of the signal used to excite each piezoelectric unit to generate ultrasonic waves can be individually modulated by the phase controller. Therefore, the signal emitted by each piezoelectric unit can be individually adjusted through the phase controller, which is beneficial to focus and direction control of the signal emitted by the entire piezoelectric structure, and further improves the resolution of fingerprint recognition using this method. rate.
  • individually modulating the phase of the signal used to excite each piezoelectric unit to generate ultrasonic waves may include: adjusting the phase of the signal applied to the plurality of piezoelectric units so that the The ultrasonic wave has the maximum amplitude at the set position. For example, adjust the phase of the signal applied to multiple piezoelectric units to shift the phase of the excitation signal applied to the piezoelectric unit, so that the ultrasonic signals generated by the multiple piezoelectric units can be superimposed during propagation and combined The ultrasonic signal has the maximum amplitude.
  • the ultrasonic signals generated by multiple piezoelectric units can be "focused", and the signal strength of the ultrasonic waves finally emitted by the piezoelectric structure can be increased.
  • the concentration of ultrasonic energy can obtain more fingerprint detection information in the depth direction. This method can further improve the sensitivity and resolution of fingerprint recognition.
  • individually modulating the phase of the signal used to excite each piezoelectric unit to generate ultrasonic waves may further include: by adjusting the phase of the signal applied to the plurality of piezoelectric units, changing the previously formed maximum The direction of the amplitude, that is, the magnitude and timing of the phase of the excitation signal of the piezoelectric unit at different spatial positions are changed, so that the direction of the maximum amplitude can be changed along a predetermined route.
  • the acoustic waves emitted by the piezoelectric structure can be focused according to a predetermined route, that is, the direction of the final ultrasonic signal can be changed, so that fingerprint detection in a larger area can be realized under a smaller piezoelectric sensor area , Improve the efficiency of human-computer interaction.
  • Changing the magnitude and timing of the phase shift of the excitation signal of the sensing unit in different spatial positions can realize the focusing and direction scanning of the ultrasound.
  • the concentration of the ultrasound energy can obtain more depth detection information, and can achieve a smaller sensor array area Next, a larger area of fingerprint detection.
  • S200 Ultrasonic waves are transmitted from the contact layer and act on the fingers.
  • the ultrasonic waves generated in the previous step are transmitted from the contact layer and act on the finger.
  • the finger contacts the contact layer, and the ultrasonic waves generated in the previous steps can be transmitted by the contact layer and act on the finger, and the finger can reflect the received ultrasonic signal back to the contact layer. Since the fingerprint of the finger has spaced peaks and troughs, there are differences in the reflection of ultrasonic waves at the peaks and troughs of the fingers. Therefore, after the action of the fingers, the ultrasonic signals reflected back to the contact layer also have differences.
  • the piezoelectric structure receives the ultrasonic signal reflected by the finger and converts it into a voltage signal.
  • the piezoelectric structure receives the ultrasonic signal reflected by the finger in the previous step and converts it into a voltage signal to realize fingerprint recognition.
  • the Young's modulus of the material forming the insulating layer is smaller than the Young's modulus of the material forming the piezoelectric unit. Therefore, as described above, due to the contact with the contact layer 300 The surface morphology of the object to be detected (for example, a finger) is different, and the fingerprint on the finger has wave crests and troughs arranged at intervals. Therefore, the ultrasonic signals received at different positions of the piezoelectric structure are also different.
  • the pressure generated by the reflected ultrasonic signal received by the subunit is F 1
  • the insulating layer 20 is formed of a softer material (the Young's modulus of the insulating layer material is smaller than the Young's modulus of the piezoelectric unit material).
  • the method further includes:
  • the piezoelectric sensor circuit is used to convert the piezoelectric signal from an AC signal to a DC signal and store it in a storage capacitor.
  • the piezoelectric sensor circuit is used to convert the piezoelectric signal from an AC signal to a DC signal and store it in a storage capacitor.
  • the voltage sensor further includes a piezoelectric sensing circuit electrically connected to the piezoelectric structure, and the piezoelectric sensing circuit can be used to convert the piezoelectric signals converted by the plurality of piezoelectric units into AC signals It is a DC signal, which is stored in the storage capacitor of the piezoelectric sensor circuit.
  • S500 Output to the peripheral signal processor in sequence in the signal output stage.
  • the storage capacitors stored in the piezoelectric sensor circuit in the previous step are sequentially output to the peripheral signal processor. Therefore, the signal of the piezoelectric structure can be easily transmitted to the peripheral signal processor, so as to process the signal fed back from the piezoelectric structure to obtain fingerprint identification information.
  • FIG. 12 is a timing diagram of a piezoelectric sensing circuit according to at least one embodiment of the present disclosure.
  • the piezoelectric sensing circuit is, for example, the piezoelectric sensing circuit shown in FIG. 9. Taking each transistor as an N-type transistor as an example, referring to the timing diagram of the piezoelectric sensing circuit shown in FIG. 12, the working process of the piezoelectric sensing circuit is as follows:
  • the first electrode layer 210 receives the excitation signal Vtx, and under the action of the excitation signal Vtx, the sensing unit emits ultrasonic waves.
  • the sampling control signal Vrst is at a high level, the first transistor M1 is turned on; the bias signal Vbias is at a low level, the second transistor M2 is turned off under the action of the bias signal Vbias, and the signal output terminal Vout does not output a signal.
  • the sampling control signal Vrst is high, the first transistor M1 is turned on; the bias signal Vbias is high, the fingerprint signal received on the receiving electrode is written into the storage capacitor Cg, and the output control signal Vsel is low Level, the fourth transistor M4 is turned off, and the signal output terminal Vout does not output a signal.
  • the length of t2 is one-quarter of the transmitted wave period, one-half of the transmitted wave period, or other lengths.
  • the first transistor M1 when the control signal Vrst is low, the first transistor M1 is turned off, the second transistor M2 is turned on by the signal in the energy storage capacitor Cg, and the output control signal Vsel is switched to high level.
  • the signal of the control electrode of the second transistor M2 is transmitted to the signal output terminal Vout, that is, the fingerprint signal is output after being amplified.
  • the t4 stage is the signal acquisition process of the other line scanning stage, that is, when the other lines are scanned, the ultrasonic waves of other lines are reflected to the current line and received by the pixel receiving circuit of the current line.
  • this method can use multiple piezoelectric units arranged at intervals to independently transmit/receive signals.
  • the ultrasonic signal emitted by the entire piezoelectric structure can be focused And direction control, etc., can increase the area of the monitoring area, reduce the occupied area of the piezoelectric sensor, and multiple piezoelectric units can improve the signal strength and resolution by forming a transmission signal with the largest amplitude.
  • the present disclosure proposes a method for preparing the aforementioned piezoelectric sensor. Therefore, the piezoelectric sensor prepared by this method has all the characteristics and advantages of the aforementioned piezoelectric sensor, and will not be repeated here. According to an embodiment of the present disclosure, referring to FIG. 13, the method includes:
  • step S10 may include:
  • a second electrode layer may be formed on the substrate.
  • a second electrode layer may be formed on one side of the glass substrate, the second electrode layer includes a plurality of sub-electrodes, and an insulating structure is provided between the plurality of sub-electrodes.
  • the material forming the second electrode layer may include indium tin oxide (ITO), etc.
  • the material forming the insulating structure may include silicon dioxide (SiO 2 ), silicon nitride (SiN x ), polyamide Imine (PI), epoxy resin, etc.
  • the second electrode layer and the piezoelectric sensing circuit may be formed on the substrate.
  • the piezoelectric sensing circuit may be formed on the substrate first, and then the second electrode layer may be formed.
  • S12 forming a plurality of piezoelectric units arranged at intervals and an insulating layer between adjacent piezoelectric units.
  • the second electrode layer formed in the previous step is away from the substrate to form a plurality of piezoelectric units arranged at intervals and an insulating layer between adjacent piezoelectric units.
  • a polyvinylidene fluoride film is spin-coated on the side of the plurality of sub-electrodes formed in the previous step away from the glass substrate, and the polyvinylidene fluoride film is used to form a plurality of arrays. And forming the insulating layer at the gap between adjacent piezoelectric units.
  • the spin-coated polyvinylidene fluoride film can be dried and then etched to form a plurality of independent piezoelectric units, and then an insulating layer material, such as epoxy resin, can be filled between adjacent piezoelectric units Or polyimide, etc., and then use a polarization process to polarize the piezoelectric unit to make it have piezoelectric characteristics.
  • the material forming the piezoelectric unit may include polyvinylidene fluoride (PVDF), PZT, AlN, and the like.
  • the thickness of the piezoelectric unit can be 5-50 ⁇ m, for example, it can be 10 ⁇ m, it can be 20 ⁇ m, it can be 30 ⁇ m, it can be 40 ⁇ m, etc.
  • the thickness of the piezoelectric unit 10 is in this range, it can transmit and receive better. Ultrasonic signal. It should be noted that, since the piezoelectric unit has been polarized in the previous step, the operating temperature should not be higher than 120°C in the subsequent manufacturing process, so as to prevent the subsequent manufacturing process from affecting the piezoelectric The use of new units can have an impact.
  • the Young's modulus of the material forming the insulating layer may be less than the Young's modulus of the material forming the piezoelectric unit.
  • the Young's modulus of the material forming the insulating layer may be no more than 2 GPa, For example, it can be 1MPa-2GPa.
  • the material constituting the insulating layer may include cured epoxy photosensitive glue, liquid optical transparent glue, polydimethylsiloxane (PDMS), and the like. Therefore, the performance of the prepared piezoelectric sensor can be further improved.
  • the first electrode layer is formed on the side of the piezoelectric unit formed in the previous step away from the second electrode layer, forming a piezoelectric structure.
  • the first electrode layer may be a whole-layer electrode, and the material forming the first electrode layer is not particularly limited, for example, it may include silver; specifically, the thickness of the first electrode layer 210 may be It is 6-12 ⁇ m, for example, it can be 8 ⁇ m, it can be 10 ⁇ m, etc., thereby further improving the usability of the prepared piezoelectric sensor.
  • the auxiliary layer in order to prevent the metal in the formed first electrode layer from diffusing into the piezoelectric layer and affecting the performance of the piezoelectric unit, it may be provided between the first electrode layer and the piezoelectric layer.
  • the auxiliary layer specifically, the auxiliary layer can be formed on the side of the piezoelectric unit prepared in the previous step away from the second electrode layer, for example, a metal molybdenum layer or a platinum layer is formed by magnetron sputtering, and then the auxiliary layer
  • the conductive silver electrode is made by sputtering or screen printing process on the side away from the second electrode layer.
  • a substrate is provided on the side of the piezoelectric structure away from the contact layer.
  • the piezoelectric structure formed in the previous step is provided with a substrate on the side away from the contact layer. That is, the substrate is formed on the side of the first electrode layer away from the piezoelectric layer.
  • the substrate may include an acoustic wave reflection sublayer and a protective sublayer sequentially formed on the side of the first electrode layer away from the piezoelectric unit.
  • the protective sublayer may be formed of an insulating material, such as epoxy resin.
  • the acoustic wave reflection sublayer may be formed of metal such as copper, and the thickness of the acoustic wave reflection sublayer may be 10-100 ⁇ m.
  • the first electrode layer prepared in the previous step may be on the side away from the piezoelectric unit, and an acoustic wave reflection sublayer, such as a copper layer, may be fabricated by an electroplating process or the like; and the acoustic wave reflection sublayer is away from the first electrode layer.
  • the side is coated with a layer of epoxy resin to form a protective sub-layer.
  • the method can easily prepare piezoelectric sensors, and the prepared piezoelectric sensors can independently transmit/receive signals through a plurality of piezoelectric units arranged at intervals, which can improve signal strength and resolution.
  • the electronic device includes any piezoelectric sensor described above. Therefore, the electronic device has all the features and advantages of the piezoelectric sensor described above, and will not be repeated here. In general, the electronic device can use a smaller piezoelectric sensor area to realize a larger area of monitoring (such as fingerprint monitoring, etc.), improve the efficiency of human-computer interaction, and have higher sensitivity and resolution during sensor monitoring. .
  • the electronic device 1200 may include the aforementioned piezoelectric sensor 1000 and a display screen 1100.
  • the piezoelectric sensor 1000 may be arranged on a side of the display screen 1100 away from the light emitting side, specifically, The piezoelectric sensor 1000 may be fixed on the side of the display screen 1100 away from the light emitting side through the optical adhesive layer 800.
  • the display screen 1100 may be an organic light-emitting display (OLED), which can reduce the energy loss and signal interference of ultrasonic transmission due to its thin thickness. Therefore, the aforementioned piezoelectric sensor is used for fingerprint recognition. The sensitivity is high.
  • the hardness of the material forming the optical adhesive layer 800 may be relatively large, for example, it may be OCA glue cured by UV; the thickness of the optical adhesive layer 800 may be less than 100 ⁇ m.
  • the electronic device may further include a cover plate 900.
  • the cover plate 900 may be a glass cover plate, the cover plate 900 is disposed above the display screen 1100, and the cover plate 900 and the display screen 1100 can also be bonded through the optical adhesive layer 800.
  • the thickness of the cover plate 900 can be as thin as possible, for example, 50-200 ⁇ m, which can further reduce the energy loss and signal interference of ultrasonic transmission, and improve the sensitivity of fingerprint recognition using the piezoelectric sensor described above.
  • the piezoelectric sensor 1000 in FIG. 16 has the structure shown in FIG. 8, the embodiments of the present disclosure are not limited to this. In other embodiments, the piezoelectric sensor 1000 in the electronic device 1200 may have the structure shown in FIG.
  • the structure of the piezoelectric sensor provided by any embodiment is disclosed, for example, the structure of the piezoelectric sensor provided by any embodiment shown in FIGS. 1A-9 and a combination of the embodiments shown in FIGS. 1A-9 The structure of the piezoelectric sensor.
  • the electronic device 1200 may also include other conventional components, such as a signal processor for processing the electrical signals output by the piezoelectric sensor to identify fingerprints, etc., which is not limited in the embodiment of the present disclosure.
  • the electronic device 1200 may be, for example, an OLED TV, electronic paper, mobile phone, tablet computer, notebook computer, digital photo frame, navigator, etc.

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Abstract

压电传感器及制备方法、进行指纹识别的方法及电子设备。该压电传感器包括相对设置的第一电极层和第二电极层；以及压电层。压电层在第一电极层与第二电极层之间，并包括间隔设置的多个压电单元以及在相邻的压电单元之间的绝缘层。第一电极层包括与多个压电单元对应的多个子电极；或第二电极层包括与多个压电单元对应的多个子电极；或第一电极层和第二电极层均包括与多个压电单元对应的多个子电极。由此，多个间隔设置的压电单元可以独立地发射/接收信号，有利于对压电结构发出的超声波信号进行聚焦和方向控制等，可以增大监测区域的面积，减小压电传感器的占用面积，并能提高信号强度和分辨率。

Description

压电传感器及制备方法、进行指纹识别的方法及电子设备
相关申请的交叉引用
本申请要求于2019年6月24日递交的第201910547611.0号中国专利申请的优先权，在此出于所有目的全文引用上述中国专利申请公开的内容以作为本申请的一部分。
技术领域
本公开的实施例涉及压电传感器及制备方法、进行指纹识别的方法及电子设备。
背景技术
压电传感器的工作原理是利用压电材料(如充当发射器)的逆压电效应(在特定方向施加交变电压使压电材料振动)发射出特定频率的超声波，超声波在传播过程中由于接触待测物体而发生能量衰减或相位变化，到达充当接收器的压电材料时发生正压电效应(在超声波的压力作用下产生电荷)，从而确定超声波的能量或相位变化以实现传感检测。具体地，可以借助压电传感器对超声波传播路径中的物理环境做出判断，比如进行指纹识别、触摸开关、压力传感器、人体内脏器官成像、金属制品探伤等。在生物特征识别领域(例如指纹识别)，压电传感器相比其他技术手段(电容式、光学式等)具有抗干扰、多维成像、便于集成等优点。
发明内容
本公开至少一个实施例提出了一种压电传感器，其包括：
相对设置的第一电极层和第二电极层；以及
压电层，在所述第一电极层与所述第二电极层之间，并包括间隔设置的多个压电单元以及在相邻的所述压电单元之间的绝缘层，
其中，所述第一电极层包括与所述多个压电单元对应的多个子电极；或
所述第二电极层包括与所述多个压电单元对应的多个子电极；或
所述第一电极层和所述第二电极层均包括与所述多个压电单元对应的多个子电极。
根据本公开的实施例，所述多个压电单元阵列排布，并且所述多个子电极与所述多个压电单元一一对应。
根据本公开的实施例，构成所述绝缘层的材料的杨氏模量，小于构成所述压电单元的材料的杨氏模量。
根据本公开的实施例，构成所述绝缘层的材料的杨氏模量不大于2GPa。
根据本公开的实施例，该压电传感器还包括绝缘结构，其中，所述绝缘结构在相邻的所述子电极之间。
根据本公开的实施例，所述第一电极层和所述第二电极层中的一个为面状电极，以及所述第一电极层和所述第二电极层中的另一个包括与所述多个压电单元对应的所述多个子电极。
根据本公开的实施例，该压电传感器还包括辅助层，所述辅助层在以下位置中的至少之一处：
所述第一电极层以及所述压电层之间；或
所述第二电极层与所述压电层之间。
根据本公开的实施例，该压电传感器还包括以下中至少之一：
激励源，所述激励源与所述第一电极层和所述第二电极层电连接，以激励多个所述压电单元产生超声波；或
相位控制器，所述相位控制器与所述第一电极层和所述第二电极层电连接，且被配置为可单独调制用以激励每个所述压电单元产生超声波的信号的相位。
根据本公开的实施例，该压电传感器还包括压电传感电路，所述压电传感电路包括：存储电容、第一晶体管、第二晶体管、第三晶体管和第四晶体管，
所述第一晶体管的控制极配置为接收采样控制信号，所述第一晶体管的第一极连接配置为接收偏置信号，
所述第二电极层、所述第一晶体管的第二极、所述存储电容的第一端和所述第二晶体管的控制极连接到第一节点，
所述存储电容的第二端连接至第一电源电压，
所述第二晶体管的第二极连接至所述第一电源电压，所述第二晶体管的第一极、所述第三晶体管的第二极和所述第四晶体管的第一极连接至第二节点，
所述第三晶体管的控制极和所述第三晶体管的第一极配置为接收第二电源电压，以及
所述第四晶体管的第二极作为所述信号读取电路的信号输出端，所述第四晶体管的控制极配置为接收输出控制信号。
根据本公开的实施例，该压电传感器还包括衬底，其中，所述衬底在所述第一电极层远离所述压电层的一侧。
本公开至少一个实施例提出了一种进行指纹识别的方法。根据本公开的实施例，该方法包括：
利用激励源激励压电传感器产生超声波，其中，所述压电传感器包括：
相对设置的第一电极层和第二电极层；以及
压电层，位于所述第一电极层和所述第二电极层之间，并包括间隔设置的多个压电单元以及在相邻的所述压电单元之间的绝缘层，
其中，所述第一电极层包括与所述多个压电单元对应的多个子电极；或
所述第二电极层包括与所述多个压电单元对应的多个子电极；或
所述第一电极层和所述第二电极层均包括与所述多个压电单元对应的多个子电极，以及
通过所述压电传感器接收经手指反射的超声波并将接收的所述超声波转换为电信号，从而实现指纹识别。
根据本公开的实施例，所述压电传感器还包括相位控制器，所述相位控制器与所述第一电极层和所述第二电极层电连接，以及
所述利用激励源激励压电传感器产生超声波包括：
利用所述相位控制器单独调制用以激励每个所述压电单元产生超声波的信号的相位。
根据本公开的实施例，所述单独调制用以激励每个所述压电单元产生超声波的信号的相位包括：调整施加在多个所述压电单元上的信号的相位，以令多个所述压电单元产生的所述超声波的信号在设定位置具有最大振幅。
根据本公开的实施例，该方法还包括：通过调整施加在多个所述压电单元上的信号的相位，改变形成的所述最大振幅的方向，以令所述最大振幅的方向可沿着预定的路线进行改变。
根据本公开的实施例，该方法还包括：利用所述压电传感器中的压电传感电路，将多个所述压电单元转换的所述电信号由交流信号转换为直流信号，分别存储在所述压电传感电路的存储电容中，并在信号读出阶段依次输出至外围信号处理器。
本公开至少一个实施例还提出了一种制备根据本公开任一实施例的压电传感器的方法。根据本公开的实施例，该方法包括：
在基板上形成第二电极层；
在所述第二电极层上形成间隔设置的多个压电单元以及位于相邻的所述压电单元之间的绝缘层；以及
在所述多个压电单元远离所述第二电极层的一侧形成第一电极层，
其中，所述第一电极层包括与所述多个压电单元对应的多个子电极；或
所述第二电极层包括与所述多个压电单元对应的多个子电极；或
所述第一电极层和所述第二电极层均包括与所述多个压电单元对应的多个子电极。
根据本公开的实施例，在所述基板上形成所述第二电极层之前，该方法还包括：在所述基板上形成压电传感电路，其中所述压电传感电路在所述第 二电极层与所述基板之间，以及所述第二电极层包括与所述多个压电单元对应的多个子电极，以及所述在所述第二电极层上形成间隔设置的所述多个压电单元以及位于相邻的所述压电单元之间的所述绝缘层，包括：在所述多个子电极远离所述基板的一侧旋涂聚偏氟乙烯薄膜，并利用所述聚偏氟乙烯薄膜形成多个阵列排布的所述压电单元，在相邻的所述压电单元的间隙处形成所述绝缘层。
根据本公开的实施例，该方法还包括：在所述第一电极层远离所述压电层的一侧提供衬底。
本公开的至少一个实施例还提出了一种电子设备。根据本公开的实施例，该电子设备包括：根据本公开任一实施例的压电传感器。
根据本公开的实施例，该电子设备还包括：显示屏，所述压电传感器设于所述显示屏背离出光侧的一侧。
根据本公开的实施例，该电子设备还包括盖板，其中，所述盖板在所述显示屏远离所述压电传感器的一侧并且所述盖板的厚度为50微米-200微米。
附图说明
为了更清楚地说明本公开实施例的技术方案，下面将对实施例的附图作简单地介绍，显而易见地，下面描述的附图仅仅涉及本公开的一些实施例，而非对本公开的限制。
图1A显示了根据本公开至少一个实施例的压电传感器的剖面结构示意图；
图1B显示了根据本公开至少一个实施例的压电传感器的剖面结构示意图；
图1C显示了根据本公开至少一个实施例的压电传感器的剖面结构示意图；
图2显示了根据本公开至少一个实施例的压电层的俯视结构示意图；
图3A显示了根据本公开另一个实施例的压电传感器的剖面结构示意图；
图3B显示了根据本公开另一个实施例的压电传感器的剖面结构示意图；
图4显示了根据本公开至少一个实施例的利用压电传感器进行指纹识别时的原理示意图；
图5显示了利用根据本公开至少一个实施例的压电传感器进行传感的原理示意图；
图6显示了利用根据本公开另一个实施例的压电传感器进行传感的原理示意图；
图7显示了根据本公开至少一个实施例的压电传感器的部分电路结构示意图；
图8显示了根据本公开又一个实施例的压电传感器的剖面结构示意图；
图9是根据本公开至少一个实施例的压电传感电路的结构示意图；
图10显示了根据本公开至少一个实施例的进行指纹识别的方法流程图；
图11显示了根据本公开另一个实施例的进行指纹识别的方法流程图；
图12是根据本公开至少一个实施例的压电传感电路的时序图；
图13显示了根据本公开至少一个实施例的制备压电传感器的方法流程图；
图14显示了根据本公开另一个实施例的制备压电传感器的方法流程图；
图15显示了根据本公开至少一个实施例的电子设备的结构示意图；以及
图16显示了根据本公开另一个实施例的电子设备的结构示意图。
具体实施方式
为使本公开实施例的目的、技术方案和优点更加清楚，下面将结合附图，对本公开实施例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公开的一部分实施例，而不是全部的实施例。基于所描述的本公开的实施例，本领域普通技术人员在无需创造性劳动的前提下所获得的所有其他实施例，都属于本公开保护的范围。
下面详细描述本公开的实施例，所述实施例的示例在附图中示出，其中自始至终相同或类似的标号表示相同或类似的元件或具有相同或类似功能的元件。下面通过参考附图描述的实施例是示例性的，仅用于解释本公开，而不能理解为对本公开的限制。
在本公开的一个方面，本公开提出了一种压电传感器。根据本公开的实施例，参考图1A-图1C以及图2(图1A-图1C为沿图2中的AA’方向的压电传感器的剖面结构示意图)，该压电传感器1000包括相对设置的衬底100、接触层300，以及位于衬底100和接触层300之间的压电结构200。其中，压电结构200包括：位于衬底100朝向接触层300一侧的第一电极层210、位于第一电极层210远离衬底100一侧的压电层230，以及位于压电层200远离衬底100一侧的第二电极层220，压电层230包括多个间隔设置的压电单元10，以及位于相邻的压电单元10之间的绝缘层20。其中，第一电极层210和/或第二电极层220，即第一电极层210和第二电极层220中的至少一个，包括多个与压电单元10对应的子电极(例如参考图1A，第二电极层220包括至少一个与压电单元10对应的子电极221)。由此，多个间隔设置的压电单元10可以独立地发射/接收信号，并且可以对整个压电结构200发出的超声波信号进行聚焦和方向控制等，提高信号强度和分辨率，并且能增大监测区域的面积，减小压电传感器的占用面积，提高人机交互效率。
应理解，在本公开的各实施例中，为了便于描述，将压电传感器1000 描述为包括接触层300，然而应理解，接触层300指的是在实际使用中，在将压电传感器1000结合至其他部件时，位于压电结构200靠近用户一侧的其他功能膜层。例如，在将压电传感器与显示屏结合在一起并且显示屏位于压电结构靠近用户的一侧时，显示屏即为接触层300。
需要说明的是，该压电传感器1000在进行工作时，前面所述的第一电极层210、第二电极层220以及压电层230可以同时作为发射器和接收器使用，即可以通过不同的工作时序，利用同一个压电层230实现超声波信号的发射，以及接收反射回的超声波信号并将其转化为电信号的过程。
为了便于理解，下面对根据本公开实施例的压电传感器能够实现上述有益效果的原理进行简单说明：
发明人发现，目前的压电传感器存在信号分辨率较低等问题。发明人通过深入研究发现，这是由目前的压电传感器中的信号容易串扰且信号强度不足等原因造成的。具体地，压电传感器在应用时(例如用于电子设备等的指纹识别时)，通常将构成压电传感器的压电材料以及电极等集成于电子设备的显示屏下方，进而可以在整个显示屏上实现较大面积的指纹识别。但是，由于目前的压电传感器中，压电材料以及电极等均为整层设置，而整层的压电材料在发射或是接收信号时，信号容易发生串扰，并且能量容易耗散，导致信号衰减，从而降低了信号分辨率，减弱了待识别目标(例如指纹)的区分度，降低了指纹识别的灵敏度和准确性等。
根据本公开实施例的压电传感器，通过将压电层(即压电材料层)图案化，即压电层包括多个间隔设置的压电单元，多个间隔设置的压电单元可以独立地发射/接收信号，即多个压电单元可以形成多个独立的压电传感器子单元。由此，可以通过独立地调节每个压电单元的信号发射情况等，对整个压电层发出的超声波信号进行聚焦和方向控制，例如可以使多个压电单元发射的信号产生干涉等，合成的超声信号可在特定位置获得最大振幅，进而可以提高信号强度，提高压电传感器的分辨率，获得类似令超声信号沿特定方向汇聚的效果，进而可以增大监测区域的面积，例如前面所述的压电传感器用于电子设备的指纹识别时，压电传感器可以仅设置在显示屏下方的部分区域，即可实现整个显示屏上的指纹识别，减小了压电传感器的占用面积，提高了人机交互效率。并且，通过单独对每一个压电单元发出的超声信号进行控制，还可以改变最大振幅的位置，即可实现扫描式的信号传感。
由于压电单元的两侧需要分别设置电极，因此，当压电层包括多个间隔设置的压电单元时，需要利用绝缘层填充压电单元之间的空隙，以保证压电单元两侧的电极结构可以获得足够的机械支撑。发明人发现，该绝缘层20还可以令相邻的压电单元在发射/接收信号时相互隔离，进而可以减小相邻的压电单元之间发射/接收信号时的电耦合，即减少了压电层在发射/接收信号 时的信号串扰，提高了压电传感器的分辨率。本领域技术人员能够理解的是，为了保证压电单元可发生前述的正压电或是逆压电效应，需要选用杨氏模量小于压电单元材料的固体绝缘层或者粘弹性胶。
根据本公开的实施例，衬底100的具体种类不受特别限制，例如衬底100可以是由绝缘材料形成的，例如环氧树脂等。具体地，参考图3A-图3B，衬底100可以包括相对设置的保护亚层110以及声波反射亚层120，其中，声波反射亚层120可以朝向压电结构200设置。具体地，保护亚层110可以是由绝缘材料，例如环氧树脂形成的。具体地，声波反射亚层120可以将传递至衬底100一侧的超声波信号反射至另一侧，减小了信号衰减，进一步提高了信号强度以及灵敏度。具体地，声波反射亚层120可以是由金属形成的，例如形成声波反射亚层120的材料可以包括铜；具体地，声波反射亚层120的厚度可以为10～100μm，例如可以为20μm，可以为50μm，可以为80μm等。由此，声波反射亚层120的厚度在该范围时，可以较好地反射传递至衬底100一侧的超声波信号。
根据本公开的实施例，压电结构200包括第一电极层210、第二电极层220以及压电层230。具体地，第一电极层210和压电层230之间、第二电极层220与压电层230之间可以形成良好的电气连接。具体地，在信号发射阶段，通过第一电极层210以及第二电极层220，可以向压电层230施加交流电压，例如施加10～20MHz的±50V的短时正弦或方波、锯齿波信号等，压电层230被该电压信号驱动，发射出超声波；在信号接收阶段，反射回的超声波可以传递至压电层230，并由压电层230将该声压转化为电信号，并传递至接收电极(例如第二电极层220上)。
根据本公开的实施例，第一电极层210以及第二电极层220中的至少之一包括多个和压电单元10对应的子电极。具体地，参照图1A，第一电极层210为整层电极，第二电极层220可包括与压电单元10对应的多个子电极221，或者参考图1B，第二电极层220可以包括和压电单元10对应多个子电极221，第一电极层210可以包括多个和压电单元10对应的子电极211，或者如图1C所示出的，第一电极层210可以包括多个和压电单元10对应的子电极211，第二电极层220可以为整层电极。形成第一电极层210的材料不受特别限制，例如可以包括银；具体地，第一电极层210的厚度可以为6-12μm，例如可以为8μm，可以为10μm等，由此，进一步提高了该压电传感器的使用性能。本领域技术人员能够理解的是，第一电极层210以及第二电极层220中的至少之一包括多个子电极，是为了实现对多个压电单元施加单独可控的电压信号。因此，只要第一电极层210以及第二电极层220中的一个具有多个独立的子电极即可。
在下文中，将以第一电极层210为整层电极和第二电极层220包括多个 子电极221为例来描述本公开的各实施例，然而应理解，本公开的实施例并不限于此。
根据本公开的实施例，参考图3A，该压电传感器1000可以进一步包括辅助层240，辅助层240可以设置在第一电极层210和压电层230之间，由此，该辅助层240不仅可以增强第一电极层210和压电层230之间的粘附性，并且可以防止第一电极层210以及声波反射亚层120中的金属原子(例如Ag、Cu等)扩散到压电单元10，进而影响压电单元10的性能等，并且可以提高该压电结构200的击穿电压。具体的，形成辅助层240的材料可以包括钼、铬、铂等，辅助层240的厚度可以为50～100nm等，且辅助层240和第一电极层210的总厚度可以为10μm左右。根据本公开的实施例，当第一电极层210为整层结构时，该辅助层240也可以为整层结构；当第一电极层210包括多个子电极时，即第一电极层210为图案化的结构时，该辅助层240也可以具有与第一电极层210相同的图案化结构。具体的，在制备该压电传感器的过程中，可以先形成层叠设置的整层结构的第一电极层210以及辅助层240，然后通过一次构图工艺，同时将该第一电极层210和辅助层240图案化，形成具有多个间隔设置的子电极的结构。
在本公开的至少一个实施例中，参照图3B，压电传感器1000还可包括辅助层241，辅助层241可设置在第二电极层220与压电层230之间，该辅助层241不仅可以增强第二电极层220和压电层230之间的粘附性，并且在第二电极层220通过金属形成的情况下，可以防止第二电极层220中的金属原子(例如Ag、Cu等)扩散到压电单元10，进而影响压电单元10的性能等，并且可以提高该压电结构200的击穿电压。例如，形成辅助层241的材料可以包括钼、铬、铂等，辅助层241的厚度可以为50～100nm等。根据本公开的实施例，当第二电极层220为整层结构时，该辅助层241也可以为整层结构；当第二电极层220包括多个子电极时，即第二电极层220为图案化的结构时，该辅助层241也可以具有与第二电极层220相同的图案化结构。具体的，在制备该压电传感器的过程中，可以先形成层叠设置的整层结构的第二电极层220以及辅助层241，然后通过一次构图工艺，同时将该第二电极层220和辅助层241图案化，形成具有多个间隔设置的子电极的结构。
根据本公开的实施例，第二电极层220可以包括多个子电极221，多个子电极221可以和多个压电单元10一一对应设置，子电极221的个数与压电单元10的个数可以相等。具体地，形成子电极221的材料不受特别限制，例如可以包括氧化铟锡(ITO)等。具体地，多个子电极221之间具有间隙，该间隙处可以形成绝缘结构，参考图2中所示出的绝缘结构222，形成该绝缘结构222的材料包括二氧化硅(SiO 2)、氮化硅(SiN x)、聚酰亚胺(PI)、环氧树脂等。
根据本公开的实施例，参考图1A、图1B、图1C以及图2，压电层230可以包括多个阵列排布的压电单元10。由此，可进一步提高该压电传感器的性能。具体地，压电单元10可以是由压电材料形成的，例如形成压电单元10的材料可以包括聚偏氟乙烯(PVDF)、锆钛酸铅压电陶瓷(PZT)、氮化铝(AlN)等。具体地，压电单元10的厚度可以为5～50μm，例如可以为10μm，可以为20μm，可以为30μm，可以为40μm等，压电单元10的厚度在该范围时，可以较好地发射以及接收超声波信号。
根据本公开的实施例，构成绝缘层20的材料的杨氏模量，可以小于构成压电单元10的材料的杨氏模量。由此，绝缘层20相对于压电单元10较软，作用于压电层230上的用于发生正压电效应(即压电材料在压力作用下产生电荷)的压力，可以集中在压电单元10上，即可以提高单个压电单元10感测到的声压，进而提高了信号强度，并且不会影响压电单元10本身的压电特性，如压电系数D 33、介电常数等；并且绝缘层20可以进一步将多个压电单元10分割开，减少相邻的压电单元10之间由于电耦合以及机械振动耦合等引起的信号串扰以及能量损耗，进一步提高了该压电传感器1000的分辨率以及灵敏度。
具体地，参考图1A、图1B、图1C以及2，该压电层230可以包括M行、N列的压电单元10阵列，每个压电单元10的尺寸可以为a×a(和每个压电单元10一一对应设置的子电极221的尺寸也为a×a)，每一行中相邻两个压电单元10之间的间距可以为b，相邻两行压电单元10之间的间距可以为b。在该压电传感器1000进行传感时，压电层230可接收经过待检测物反射的超声波信号，由于与接触层300接触的待检测物(例如手指)的表面形貌存在差异，例如参考图7，手指700上的指纹为间隔排列的波峰和波谷，因此，压电层230的不同位置处接收到的超声波信号也存在差异。对于每一个压电单元10及其周边的绝缘层20形成的子单元231(参考图4中的加粗实线框标出的子单元231)，该子单元231接收到的反射回的超声波信号产生的压力为F 1，该子单元231的面积为S 1＝(a+b) 2，当该子单元231中的绝缘层20由杨氏模量较大的材料(较硬)形成时，该压力F 1作用于整个子单元231上，该子单元231上产生的压强为P 1＝F 1/S 1。而根据本公开实施例的压电传感器1000中，绝缘层20为较软的材料(绝缘层材料的杨氏模量小于压电单元材料的杨氏模量)形成的，因此，该子单元231接收到的反射回的超声波信号产生的压力为F 1将几乎全部施加于面积为S 2＝a 2的压电单元10上，因此在压电单元10上产生的压强为P 2＝F 1/S 2，P 2大于P 1，因此，压电单元10接收到的声压(即反射的超声波产生的压强)得到放大。因此，提高了信号强度和检测灵敏度。
根据本公开的实施例，构成绝缘层20的材料的杨氏模量可以不大于 2GPa，例如，可以为1MPa-2GPa。由此，可进一步提高该压电传感器的性能。具体地，构成绝缘层20的材料可以包括经固化的环氧光敏胶、液态光学透明胶、聚二甲基硅氧烷(PDMS)等。
根据本公开的实施例，接触层300的具体类型不受特别限制，例如可以为玻璃基板、显示屏等。具体地，如前所述，形成接触层300的材料的杨氏模量可以大于形成压电单元10的材料的杨氏模量，即接触层300可以较硬。
根据本公开的实施例，参考图5以及图6，压电传感器1000可以进一步包括激励源400，激励源400与压电结构电连接，以激励多个压电单元20产生超声波。具体地，激励源400可以和第一电极层210以及第二电极层220电连接，在信号发射阶段，激励源400可以通过第一电极层210以及第二电极层220(多个和压电单元10电连接的子电极)，向每个压电单元10施加交流电压，例如施加10～20MHz的±50V的短时正弦或方波、锯齿波信号等，压电单元10被该电压信号驱动，分别发射出超声波，并且，多个压电单元10发射出的超声波在传播一定距离之后，可以合成为近似平面波。如前所述，由于多个压电单元10之间的绝缘层20的杨氏模量较小，因此，多个压电单元10之间无机械耦合损失，因此，可以减少能量耗散，提高了最终由该压电结构发射出的合成平面波的强度，提高信号强度和监测灵敏度。
根据本公开的实施例，参考图6，压电传感器1000可以进一步包括相位控制器600，相位控制器600可以与压电结构电连接，且可以单独调制用以激励每个压电单元10产生超声波的信号的相位。由此，通过该相位控制器600，可以对每个压电单元10发射的超声波信号进行单独调控(例如可以对不同的压电单元10施加不同时间延迟的激励信号)，多个压电单元发射的超声波信号的相位可以相同，也可以不同(参考图6所示出的)，从而可以对整个压电层230发射的信号进行聚焦以及方向控制等，由此，可以增大监测区域的面积，即可以在较小的压电传感器1000的面积的基础上，实现更大面积的传感和监测。例如前面所述的压电传感器用于电子设备的指纹识别时，压电传感器可以仅设置在显示屏下方的部分区域，即可实现整个显示屏上的指纹识别，减小了压电传感器的占用面积，提高了人机交互效率，进一步提高了该压电传感器的使用性能。
根据本公开的实施例，参考图5以及图6，压电传感器1000可以进一步包括压电传感电路500，压电传感电路500与压电结构电连接。压电传感电路500例如可以与压电结构一一对应。由此，在信号接收阶段，利用该压电传感电路500，可以将压电层230接收到反射波并转化产生的电信号输出至外围的信号处理器，以便对该压电传感器1000的监测结果进行分析和判断。具体地，该压电传感电路500可以将多个压电单元10转换的电信号由交流信号转换为直流信号，分别存储在压电传感电路500的存储电容中，并在信号 读出阶段依次输出至外围信号处理器。
根据本公开的实施例，参考图7以及图8，压电传感电路500可以设置第二电极层220远离第一电极层210的一侧。具体的，压电传感电路500可以包括控制与发射电路、检测电路(图中未示出)以及TFT电路等。前面所述的激励源以及相位传感器可以通过该控制与发射电路控制施加在第一电极层和第二电极层之间的交流电压等，进而可以控制每个压电单元发射的超声波信号的相位等，以便根据需要对整个压电结构发射的超声波信号进行调节。该检测电路以及TFT电路等可以将每个压电单元接收到反射波并转化产生的电信号按照一定的顺序，依次输出至外围的信号处理器。
图9是根据本公开至少一个实施例的压电传感电路500的结构示意图。如图9所示，压电传感电路500包括：存储电容Cg、第一晶体管M1和信号读取电路。第一晶体管M1的控制极配置为接收采样控制信号Vrst，第一晶体管M1的第一极配置为接收偏置信号Vbias。第二电极层220、第一晶体管M1的第二极、存储电容Cg的第一端和信号读取电路的第一端连接到第一节点N1。存储电容Cg的第二端连接至第一电源电压Vss。信号读取单元配置读取存储电容Cg中存储的电信号，即第二电极层220接收到的电压信号。
例如，在本公开的至少一个实施例中，信号读取电路可包括第二晶体管M2、第三晶体管M3和第四晶体管M4。第二晶体管M2的控制极作为信号读取电路的第一端，第二晶体管M2的第二极连接至第一电源电压Vss，第二晶体管M2的第一极、第三晶体管M3的第二极和第四晶体管M4的第一极连接至第二节点N2。第三晶体管M3的控制极和第三晶体管M3的第一极配置为接收第二电源电压Vdd。第四晶体管M4的第二极作为信号读取电路的信号输出端Vout，第四晶体管M4的控制极配置为接收输出控制信号Vsel。第二电源电压Vdd高于第一电源电压Vss，例如，第一电源电压Vss例如为低电压，例如接地，第二电源电压例如为恒定的高电压。
应理解，图9中仅示出了信号读取电路的一种示例性结构，在其他实施例中，信号读取电路还可具有其他的结构，只要信号读取电路能够读取存储电容Cg中存储的电信号，本公开的实施例对此不作限制。
本公开的实施例中采用的晶体管均可以为薄膜晶体管或场效应晶体管或其他特性相同的开关器件。这里采用的晶体管的源极、漏极在结构上可以是对称的，所以其源极、漏极在结构上可以是没有区别的。例如，上述的晶体管均可以是N型晶体管，第一极可以是漏极，第二极可以是源极。
综上可知，根据本公开实施例的压电传感器，通过设置多个间隔分布的压电单元，多个间隔设置的压电单元可以独立地发射/接收信号，减少了压电结构在发射/接收信号时的电耦合，减少了信号串扰，并且可以对整个压电结构发出的超声波信号进行聚焦和方向控制等，可以进一步提高信号强度和分 辨率，并且能增大监测区域的面积，减小压电传感器的占用面积，提高人机交互效率。
在本公开的另一方面，本公开提出了一种进行指纹识别的方法。根据本公开的实施例，该方法可以是利用前面所述的任一压电传感器进行指纹识别的，由此，该方法具有前面所述的压电传感器所具有的全部特征以及优点，在此不再赘述。
根据本公开的实施例，参考图10，该方法包括：
S100：利用激励源激励电压传感器产生超声波。
在该步骤中，利用激励源激励压电传感器产生超声波。根据本公开的实施例，该电压传感器具有前面所述任一的电压传感器相同的结构，例如该压电传感器包括相对设置的第一电极层和第二电极层以及压电层。压电层位于第一电极层和第二电极层之间并包括间隔设置的多个压电单元以及在相邻的压电单元之间的绝缘层。第一电极层和第二电极层中的至少一个包括多个与压电单元对应的子电极。具体地，该步骤中，激励源可以和第一电极层以及第二电极层电连接，激励源可以通过第一电极层以及第二电极层(多个和压电单元电连接的子电极)，向每个压电单元施加交流电压，例如施加10～20MHz的±50V的短时正弦或方波、锯齿波信号等，压电单元被该电压信号驱动，分别发射出超声波，并且，多个压电单元发射出的超声波在传播一定距离之后，可以合成为近似平面波。
根据本公开的实施例，压电传感器还可以包括相位控制器，该相位控制器和压电结构电连接，可以利用相位控制器单独调制用以激励每个压电单元产生超声波的信号的相位。由此，通过该相位控制器可以对每个压电单元发射的信号进行单独调控，有利于对整个压电结构发射的信号进行聚焦以及方向控制等，进一步提高了利用该方法进行指纹识别的分辨率。
根据本公开的一些实施例，单独调制用以激励每个压电单元产生超声波的信号的相位可以包括：调整施加在多个压电单元上的信号的相位，以令多个压电单元产生的超声波在设定位置具有最大振幅。例如，调整施加在多个压电单元上的信号的相位，使施加到压电单元的激励信号的相位发生偏移，以令多个压电单元产生的超声波的信号可在传播途中叠加，合成的超声信号具有最大振幅。由此，可以对多个压电单元产生的超声波信号进行“聚焦”，可以提高最终由压电结构发射出的超声波的信号强度，超声能量的集中能够获得更多的深度方向的指纹探测信息，可进一步提高该方法进行指纹识别的灵敏度以及分辨率。
根据本公开的另一些实施例，单独调制用以激励每个压电单元产生超声波的信号的相位还可以进一步包括：通过调整施加在多个压电单元上的信号的相位，改变前面形成的最大振幅的方向，即改变不同空间位置的压电单元 的激励信号的相位的大小和时序，以令该最大振幅的方向可沿着预定的路线进行改变。由此，可以对该压电结构发射的声波按预定的路线进行聚焦，即可以改变最终产生的超声波信号的方向，从而可以在较小的压电传感器面积下，实现较大面积区域的指纹监测，提高了人机交互效率。改变不同空间位置的传感单元激励信号相移的大小和时序，可实现超声波的聚焦和方向扫描，超声能量的集中能够获得更多的深度方向的探测信息，并能够实现在较小传感器阵列面积下对更大面积的指纹检测。
S200：超声波由接触层传出并作用于手指。
在该步骤中，前面步骤中产生的超声波由接触层传出，并作用于手指。根据本公开的实施例，该过程中，手指和接触层接触，进而前面步骤中产生的超声波可由接触层传递并作用于手指，手指可以将该接收到的超声波信号反射回接触层。由于手指的指纹具有间隔的波峰和波谷，手指的波峰和波谷处对超声波的反射存在差异，因此，经过手指作用后，反射回接触层的超声波信号也出现差异。
S300：压电结构接收手指反射的超声波信号，并转换为电压信号。
在该步骤中，压电结构接收前面步骤中由手指反射回的超声波信号，并将其转换为电压信号，从而实现指纹识别。根据本公开的实施例，该压电传感器中，形成绝缘层的材料的杨氏模量小于形成压电单元的材料的杨氏模量，因此，如前所述，由于与接触层300接触的待检测物(例如手指)的表面形貌存在差异，手指上的指纹为间隔排列的波峰和波谷，因此，压电结构的不同位置处接收到的超声波信号也存在差异。对于每一个压电单元及其周边的绝缘层形成的子单元，该子单元接收到的反射回的超声波信号产生的压力为F 1，该子单元231的面积为S 1＝(a+b) 2，当该子单元231中的绝缘层由杨氏模量较大的材料(较硬)形成时，该压力F 1作用于整个子单元231上，该子单元231上产生的压强为P 1＝F 1/S 1。而根据本公开实施例的压电传感器1000中，绝缘层20为较软的材料(绝缘层材料的杨氏模量小于压电单元材料的杨氏模量)形成的，因此，该子单元231接收到的反射回的超声波信号产生的压力为F 1将几乎全部施加于面积为S 2＝a 2的压电单元上，因此在压电单元10上产生的压强为P 2＝F 1/S 2，P 2大于P 1，因此，压电单元10接收到的声压(即反射的超声波产生的压强)得到放大。因此，提高了信号强度和检测灵敏度。
根据本公开的实施例，参考图11，该方法进一步包括：
S400：利用压电传感电路，将压电信号由交流信号转变为直流信号，存储在存储电容中。
该步骤中，利用压电传感电路，将压电信号由交流信号转变为直流信号，存储在存储电容中。根据本公开的实施例，该电压传感器进一步包括和压电 结构电连接的压电传感电路，并且可以利用该压电传感电路，将多个压电单元转换的压电信号由交流信号转换为直流信号，分别存储在压电传感电路的存储电容中。
S500：在信号输出阶段依次输出至外围信号处理器。
在该步骤中，在信号读出阶段，将前面步骤中存储在压电传感电路的存储电容，依次输出至外围信号处理器。由此，可以简便地将压电结构的信号传递至外围信号处理器，以便对压电结构反馈的信号进行处理，得到指纹识别信息。
图12是根据本公开至少一个实施例的压电传感电路的时序图，该压电传感电路例如为图9所示的压电传感电路。以各晶体管为N型晶体管为例进行说明，参考图12所示的压电传感电路的时序图，该压电传感电路的工作过程如下：
在t1阶段：第一电极层210接收激励信号Vtx，在激励信号Vtx的作用下，传感单元发射超声波。采样控制信号Vrst为高电平，第一晶体管M1导通；偏置信号Vbias为低电平，第二晶体管M2在偏置信号Vbias的作用下关断，信号输出端Vout不输出信号。
在t2阶段：采样控制信号Vrst为高电平，第一晶体管M1导通；偏置信号Vbias为高电平，接收电极上接收到的指纹信号被写入存储电容Cg，输出控制信号Vsel为低电平，第四晶体管M4关断，信号输出端Vout不输出信号。例如，t2的长度为四分之一发射波周期、二分之一发射波周期或其他长度。
在t3阶段：采用控制信号Vrst为低电平，第一晶体管M1关断，第二晶体管M2在储能电容Cg中的信号的驱动下导通，输出控制信号Vsel切换为高电平，此时第二晶体管M2的控制极的信号被传输至信号输出端Vout，也即是指纹信号在放大后被输出。
在t4阶段：t4阶段为其他行扫描阶段的信号采集过程，也即是在其他行进行扫描时，其他行的超声波反射至当前行，通过当前行的像素接收电路进行接收。
综上可知，该方法可利用多个间隔设置的压电单元独立地发射/接收信号，通过独立地调节每个压电单元的信号发射情况等，可以对整个压电结构发出的超声波信号进行聚焦和方向控制等，可以增大监测区域的面积，减小压电传感器的占用面积，并且多个压电单元可通过诸如形成具有最大振幅的发射信号等方式，能提高信号强度和分辨率。
在本公开的又一方面，本公开提出了一种制备前面所述的压电传感器的方法。由此，该方法所制备的压电传感器具有前面所述的压电传感器所具有的全部特征以及优点，在此不再赘述。根据本公开的实施例，参考图13，该 方法包括：
S10：在接触层上形成压电结构。
在该步骤中，在接触层上形成压电结构。根据本公开的实施例，接触层可以为玻璃基板等。根据本公开的实施例，参考图14，步骤S10可包括：
S11：形成第二电极层。
在该步骤S11中，可以在基板上形成第二电极层。根据本公开的实施例，基板为玻璃基板时，可以在玻璃基板的一侧形成第二电极层，该第二电极层包括多个子电极，且多个子电极之间具有绝缘结构。具体地，如前所述，形成第二电极层的材料可以包括氧化铟锡(ITO)等，形成绝缘结构的材料可以包括二氧化硅(SiO 2)、氮化硅(SiN x)、聚酰亚胺(PI)、环氧树脂等。
根据本公开的实施例，该步骤中，可以在基板上形成第二电极层以及压电传感电路，具体地，可以先在基板上形成压电传感电路，然后再形成第二电极层。
S12：形成多个间隔设置的压电单元以及相邻压电单元之间的绝缘层。
在该步骤中，在前面步骤中形成的第二电极层远离基板的一侧，形成多个间隔设置的压电单元以及相邻压电单元之间的绝缘层。根据本公开的实施例，该步骤中，在前面步骤中形成的多个子电极远离玻璃基板的一侧旋涂聚偏氟乙烯薄膜，并利用该聚偏氟乙烯薄膜形成多个阵列排布的压电单元，并在相邻的压电单元的间隙处形成所述绝缘层。具体地，可以将该旋涂的聚偏氟乙烯薄膜烘干后进行刻蚀处理，形成多个独立的压电单元，然后在相邻的压电单元之间填充绝缘层材料，例如环氧树脂或聚酰亚胺等，再使用极化工艺对压电单元进行极化，使其具备压电特性。具体地，形成压电单元的材料可以包括聚偏氟乙烯(PVDF)、PZT、AlN等。具体地，压电单元的厚度可以为5～50μm，例如可以为10μm，可以为20μm，可以为30μm，可以为40μm等，压电单元10的厚度在该范围时，可以较好地发射以及接收超声波信号。需要说明的是，由于前面步骤中，已经对形成的压电单元进行了极化处理，因此，在后续的制备工艺中，操作温度应不高于120℃，以免后续的制备工艺对该压电单元的使用新能造成影响。
具体地，如前所述，形成绝缘层的材料的杨氏模量可以小于形成压电单元的材料的杨氏模量，例如，构成绝缘层的材料的杨氏模量可以为不大于2GPa，例如，可以为1MPa-2GPa。由此，可进一步提高该压电传感器的性能。具体地，构成绝缘层的材料可以包括经固化的环氧光敏胶、液态光学透明胶、聚二甲基硅氧烷(PDMS)等。由此，可以进一步提高所制备的该压电传感器的使用性能。
S13：在压电单元远离第二电极层的一侧形成第一电极层。
在该步骤中，在前面步骤中形成的压电单元远离第二电极层的一侧形成 第一电极层，形成了压电结构。根据本公开的实施例，如前所述，第一电极层可以为整层电极，形成第一电极层的材料不受特别限制，例如可以包括银；具体地，第一电极层210的厚度可以为6-12μm，例如可以为8μm，可以为10μm等，由此，进一步提高了制备的该压电传感器的使用性能。根据本公开的实施例，如前所述，为了避免形成的第一电极层中的金属扩散到压电层中，影响压电单元的性能，在第一电极层和压电层之间可以设置辅助层，具体的，可以在前面步骤中制备的压电单元远离第二电极层的一侧先形成辅助层，例如通过磁控溅射的方法形成金属钼层或铂层，然后在该辅助层远离第二电极层的一侧通过溅射或丝网印刷工艺等制作导电银电极。
S20：在压电结构远离接触层的一侧设置衬底。
在该步骤中，在前面步骤中形成的压电结构远离所述接触层的一侧设置衬底。也即，在第一电极层远离压电层的一侧形成衬底。根据本公开的实施例，该衬底可以包括依次形成在第一电极层远离压电单元的一侧的声波反射亚层以及保护亚层。具体地，如前所述，保护亚层可以是由绝缘材料，例如环氧树脂形成的。声波反射亚层可以是由金属例如铜形成的，声波反射亚层的厚度可以为10～100μm。由此，可以进一步提高所制备的压电传感器的使用性能。具体地，可以在前面步骤中制备的第一电极层远离压电单元的一侧，通过电镀工艺等制作声波反射亚层，例如铜层；并在该声波反射亚层远离第一电极层的一侧涂覆一层环氧树脂等，形成保护亚层。综上可知，该方法可以简便地制备压电传感器，且制备的压电传感器通过多个间隔设置的压电单元可以独立地发射/接收信号，可以提高信号强度以及分辨率。
在本公开的又一方面，本公开的至少一个实施例提出了一种电子设备。根据本公开的实施例，该电子设备包括：前面所述任一的压电传感器。由此，该电子设备具有前面所述的压电传感器所具有的全部特征以及优点，在此不再赘述。总的来说，该电子设备可以利用较小的压电传感器面积，实现较大面积的监测(例如指纹监测等)，提高了人机交互效率，且传感监测时的灵敏度和分辨率较高。
根据本公开的实施例，参考图15，该电子设备1200可以包括前面所述的压电传感器1000以及显示屏1100，压电传感器1000可以设于显示屏1100背离出光侧的一侧，具体地，压电传感器1000可以通过光学粘合层800固设在显示屏1100背离出光侧的一侧。具体地，显示屏1100可以为有机发光显示屏(OLED)，OLED显示屏由于厚度较薄，可以减少超声波传输的能量损失和信号干扰，因此，利用前面所述的压电传感器进行指纹识别时的灵敏度较高。具体的，形成光学粘合层800的材料的硬度可以较大，例如可以为通过UV固化的OCA胶；光学粘合层800的厚度可以在100μm以下。由此，可以进一步减少超声波传输的能量损失和信号干扰，提高利用前面所述的压 电传感器进行指纹识别时的灵敏度。根据本公开的实施例，参考图16，该电子设备可以进一步包括盖板900。具体的，盖板900可以为玻璃盖板，盖板900设置在显示屏1100的上方，且盖板900和显示屏1100之间也可以通过光学粘合层800粘合。具体的，盖板900的厚度可以尽可能薄，例如可以为50～200μm，由此，可以进一步减少超声波传输的能量损失和信号干扰，提高利用前面所述的压电传感器进行指纹识别时的灵敏度。应理解，虽然在图16中的压电传感器1000具有图8所示的结构，然而本公开的实施例并不限于此，在其他实施例中，电子设备1200中的压电传感器1000可具有本公开任一实施例提供的压电传感器的结构，例如图1A-图9所示的任一实施例提供的压电传感器的结构以及将图1A-图9所示的实施例进行组合而得到的压电传感器的结构。
此外，应理解，电子设备1200还可包括其他常规部件，例如用于对压电传感器输出的电信号进行处理以识别指纹的信号处理器等，本公开的实施例对此不作限制。
电子设备1200例如可以是OLED电视、电子纸、手机、平板电脑、笔记本电脑、数码相框、导航仪等。
在本说明书的描述中，术语“上”、“下”等指示的方位或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公开而不是要求本公开必须以特定的方位构造和操作，因此不能理解为对本公开的限制。
在本说明书的描述中，参考术语“一个实施例”、“另一个实施例”等的描述意指结合该实施例描述的具体特征、结构、材料或者特点包含于本公开的至少一个实施例中。在本说明书中，对上述术语的示意性表述不必须针对的是相同的实施例或示例。而且，描述的具体特征、结构、材料或者特点可以在任一个或多个实施例或示例中以合适的方式结合。此外，在不相互矛盾的情况下，本领域的技术人员可以将本说明书中描述的不同实施例或示例以及不同实施例或示例的特征进行结合和组合。另外，需要说明的是，本说明书中，术语“第一”、“第二”仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。
以上所述仅是本公开的示范性实施方式，而非用于限制本公开的保护范围，本公开的保护范围由所附的权利要求确定。

Claims (21)

  1. 一种压电传感器，包括：
    相对设置的第一电极层和第二电极层；以及
    压电层，在所述第一电极层与所述第二电极层之间，并包括间隔设置的多个压电单元以及在相邻的所述压电单元之间的绝缘层，
    其中，所述第一电极层包括与所述多个压电单元对应的多个子电极；或所述第二电极层包括与所述多个压电单元对应的多个子电极；或
    所述第一电极层和所述第二电极层均包括与所述多个压电单元对应的多个子电极。
  2. 根据权利要求1所述的压电传感器，其中，所述多个压电单元阵列排布，并且所述多个子电极与所述多个压电单元一一对应。
  3. 根据权利要求1或2所述的压电传感器，其中，构成所述绝缘层的材料的杨氏模量小于构成所述压电单元的材料的杨氏模量。
  4. 根据权利要求3所述的压电传感器，其中，构成所述绝缘层的材料的杨氏模量不大于2GPa。
  5. 根据权利要求1至4中任一项所述的压电传感器，还包括绝缘结构，其中，所述绝缘结构在相邻的所述子电极之间。
  6. 根据权利要求1至5中任一项所述的压电传感器，其中，
    所述第一电极层和所述第二电极层中的一个为面状电极，以及
    所述第一电极层和所述第二电极层中的另一个包括与所述多个压电单元对应的所述多个子电极。
  7. 根据权利要求1至6中任一项所述的压电传感器，还包括辅助层，所述辅助层在以下位置中的至少之一处：
    所述第一电极层以及所述压电层之间；或
    所述第二电极层与所述压电层之间。
  8. 根据权利要求1至7中任一项所述的压电传感器，还包括以下中至少之一：
    激励源，所述激励源与所述第一电极层和所述第二电极层电连接，以激励多个所述压电单元产生超声波；或
    相位控制器，所述相位控制器与所述第一电极层和所述第二电极层电连接，且被配置为可单独调制用以激励每个所述压电单元产生超声波的信号的相位。
  9. 根据权利要求1至8中任一项所述的压电传感器，还包括压电传感电路，所述压电传感电路包括：存储电容、第一晶体管、第二晶体管、第三晶体管和第四晶体管，
    所述第一晶体管的控制极配置为接收采样控制信号，所述第一晶体管的第一极连接配置为接收偏置信号，
    所述第二电极层、所述第一晶体管的第二极、所述存储电容的第一端和所述第二晶体管的控制极连接到第一节点，
    所述存储电容的第二端连接至第一电源电压，
    所述第二晶体管的第二极连接至所述第一电源电压，所述第二晶体管的第一极、所述第三晶体管的第二极和所述第四晶体管的第一极连接至第二节点，
    所述第三晶体管的控制极和所述第三晶体管的第一极配置为接收第二电源电压，以及
    所述第四晶体管的第二极作为所述信号读取电路的信号输出端，所述第四晶体管的控制极配置为接收输出控制信号。
  10. 根据权利要求1至9中任一项所述的压电传感器，还包括衬底，
    其中，所述衬底在所述第一电极层远离所述压电层的一侧。
  11. 一种进行指纹识别的方法，包括：
    利用激励源激励压电传感器产生超声波，其中，所述压电传感器包括：
    相对设置的第一电极层和第二电极层；以及
    压电层，位于所述第一电极层和所述第二电极层之间，并包括间隔设置的多个压电单元以及在相邻的所述压电单元之间的绝缘层，
    其中，所述第一电极层包括与所述多个压电单元对应的多个子电极；或
    所述第二电极层包括与所述多个压电单元对应的多个子电极；或
    所述第一电极层和所述第二电极层均包括与所述多个压电单元对应的多个子电极，以及
    通过所述压电传感器接收经手指反射的超声波并将接收的所述超声波转换为电信号，从而实现指纹识别。
  12. 根据权利要求11所述的方法，其中，所述压电传感器还包括相位控制器，所述相位控制器与所述第一电极层和所述第二电极层电连接，以及
    所述利用激励源激励压电传感器产生超声波，包括：
    利用所述相位控制器单独调制用以激励每个所述压电单元产生超声波的信号的相位。
  13. 根据权利要求12所述的方法，其中，所述单独调制用以激励每个所述压电单元产生超声波的信号的相位，包括：
    调整施加在多个所述压电单元上的信号的相位，以令多个所述压电单元产生的所述超声波在设定位置具有最大振幅。
  14. 根据权利要求13所述的方法，还包括：
    通过调整施加在多个所述压电单元上的信号的相位，改变形成的所述最 大振幅的方向，以令所述最大振幅的方向可沿着预定的路线进行改变。
  15. 根据权利要求11至14中任一项所述的方法，还包括：利用所述压电传感器中的压电传感电路，将多个所述压电单元转换的所述电信号由交流信号转换为直流信号，分别存储在所述压电传感电路的存储电容中，并在信号读出阶段依次输出至外围信号处理器。
  16. 一种制备压电传感器的方法，包括：
    在基板上形成第二电极层；
    在所述第二电极层上形成间隔设置的多个压电单元以及位于相邻的所述压电单元之间的绝缘层；以及
    在所述多个压电单元远离所述第二电极层的一侧形成第一电极层，
    其中，所述第一电极层包括与所述多个压电单元对应的多个子电极；或
    所述第二电极层包括与所述多个压电单元对应的多个子电极；或
    所述第一电极层和所述第二电极层均包括与所述多个压电单元对应的多个子电极。
  17. 根据权利要求16所述的方法，其中，
    在所述基板上形成所述第二电极层之前，所述方法还包括：
    在所述基板上形成压电传感电路，其中所述压电传感电路在所述第二电极层与所述基板之间，以及
    所述第二电极层包括与所述多个压电单元对应的多个子电极，以及所述在所述第二电极层上形成间隔设置的所述多个压电单元以及位于相邻的所述压电单元之间的所述绝缘层，包括：
    在所述多个子电极远离所述基板的一侧旋涂聚偏氟乙烯薄膜，并利用所述聚偏氟乙烯薄膜形成多个阵列排布的所述压电单元，在相邻的所述压电单元的间隙处形成所述绝缘层。
  18. 根据权利要求16或17所述的方法，还包括：在所述第一电极层远离所述压电层的一侧提供衬底。
  19. 一种电子设备，包括：权利要求1-10任一项所述的压电传感器。
  20. 根据权利要求19所述的电子设备，还包括：
    显示屏，所述压电传感器设于所述显示屏背离出光侧的一侧。
  21. 根据权利要求20所述的电子设备，还包括盖板，
    其中，所述盖板在所述显示屏远离所述压电传感器的一侧并且所述盖板的厚度为50微米-200微米。
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