Ultrasonic sensor, method for manufacturing ultrasonic sensor, and display device

Abstract

An ultrasonic sensor, a method for preparing an ultrasonic sensor, and a display device. The ultrasonic sensor includes a texture recognition area and a control area. The control area is located on at least one side of the texture recognition area; the texture recognition area includes at least one recognition unit, and the control area includes at least one control unit; at least one recognition unit includes a first dielectric material layer; at least one control unit includes a second dielectric material layer; the first dielectric material layer and the second dielectric material layer are made of the same material; the first dielectric material layer has piezoelectric properties; and the piezoelectric strain constant of the first dielectric material layer is greater than the piezoelectric strain constant of the second dielectric material layer. The ultrasonic sensor can improve the signal-to-noise ratio.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to an ultrasonic sensor, a method for manufacturing the ultrasonic sensor, and a display device. Background Art

[0002] Ultrasonic sensors use the propagation characteristics of ultrasonic waves in propagation media (such as human tissue, steel, water, etc.) such as reflection, refraction, diffraction, and attenuation to infer the shape, size, and other information of the target object. Ultrasonic sensors are a non-destructive testing method, and in some specific occasions, compared with sensors based on optical, electromagnetic wave and other technologies, ultrasonic sensors have unique advantages. Piezoelectric materials are materials used to effectively excite or generate ultrasonic waves.

[0003] At present, fingerprint collection devices based on ultrasonic technology all use the principle of acoustic impedance difference of fingerprint valleys and ridges. Specifically, when the ultrasonic wave excited by the ultrasonic wave transmitting component reaches the fingerprint surface through the propagation medium, since the location of the fingerprint valley is air, the acoustic impedance at the interface corresponding to the fingerprint valley is seriously mismatched, which makes most (almost 100%) of the ultrasonic wave energy reflected (reflected by the interface); however, since the acoustic impedance matching of the interface corresponding to the fingerprint ridge is better, only a small amount of ultrasonic wave energy is reflected; the reflected ultrasonic wave is then converted into an electrical signal by the ultrasonic wave receiving component through the propagation medium. After processing the electrical signal, an image of the fingerprint valley distribution can be obtained. Summary of the invention

[0004] At least one embodiment of the present disclosure provides an ultrasonic sensor, which includes a texture recognition area and a control area. The control area is located on at least one side of the texture recognition area; the texture recognition area includes at least one recognition unit, and the control area includes at least one control unit; the at least one recognition unit includes a first dielectric material layer; the at least one control unit includes a second dielectric material layer; the first dielectric material layer and the second dielectric material layer are made of the same material; the first dielectric material layer has piezoelectric properties; and the piezoelectric strain constant of the first dielectric material layer is greater than the piezoelectric strain constant of the second dielectric material layer.

[0005] For example, in at least one example of the ultrasonic sensor, a ratio of a piezoelectric strain constant of the first dielectric material layer to a piezoelectric strain constant of the second dielectric material layer is greater than or equal to 2.

[0006] For example, in at least one example of the ultrasonic sensor, the first dielectric material layer and the second dielectric material layer include polyvinylidene fluoride films, and the polyvinylidene fluoride film included in the first dielectric material layer and the polyvinylidene fluoride film included in the second dielectric material layer.

[0007] For example, in at least one example of the ultrasonic sensor, the ultrasonic sensor further includes a back plate, and an orthographic projection of the second dielectric material layer on the back plate and an orthographic projection of the first dielectric material layer on the back plate are spaced apart from each other.

[0008] For example, in at least one example of the ultrasonic sensor, the control area includes a first sub-control area and a second sub-control area; and the first sub-control area and the second sub-control area are located on both sides of the pattern recognition area in the first direction.

[0009] For example, in at least one example of the ultrasonic sensor, the at least one identification unit also includes a first sub-electrode and a second sub-electrode; the first dielectric material layer is sandwiched between the first sub-electrode and the second sub-electrode in a direction perpendicular to the ultrasonic sensor; the at least one control unit also includes a third sub-electrode and a fourth sub-electrode; and the second dielectric material layer is sandwiched between the third sub-electrode and the fourth sub-electrode in a direction perpendicular to the ultrasonic sensor.

[0010] For example, in at least one example of the ultrasonic sensor, the first sub-electrode and the third sub-electrode are located in a first electrode layer; the second sub-electrode and the fourth sub-electrode are located in a second electrode layer; the first sub-electrode and the third sub-electrode have the same shape and size; and the second sub-electrode and the fourth sub-electrode have the same shape and size.

[0011] For example, in at least one example of the ultrasonic sensor, the ultrasonic sensor further includes a backplane, a first routing line and a second routing line. Both the first routing line and the second routing line can be electrically connected to the fourth sub-electrode; the first routing line extends from the position where it is electrically connected to the fourth sub-electrode to the edge of the backplane; and the orthographic projection of the end of the second routing line on the backplane is spaced from the edge of the backplane.

[0012] For example, in at least one example of the ultrasonic sensor, the ultrasonic sensor further includes a third routing, a fourth routing, a fifth routing, and a sixth routing. The third routing may be electrically connected to the first sub-electrode, the fourth routing may be electrically connected to the third sub-electrode; the fifth routing may be electrically connected to the first sub-electrode, the sixth routing may be electrically connected to the third sub-electrode; the third routing extends from a position electrically connected to the first sub-electrode to an edge of the back plate; and the fourth routing extends from a position electrically connected to the third sub-electrode to an edge of the back plate.

[0013] For example, in at least one example of the ultrasonic sensor, the ultrasonic sensor further includes a back plate, a seventh routing line, and an eighth routing line. The seventh routing line may be electrically connected to the first sub-electrode, and the eighth routing line may be electrically connected to the first sub-electrode; the seventh routing line extends from a position electrically connected to the first sub-electrode to an edge of the back plate; and an orthographic projection of an end of the eighth routing line on the back plate is spaced from the edge of the back plate.

[0014] For example, in at least one example of the ultrasonic sensor, the backplane includes at least one first pixel unit circuit and at least one second pixel unit circuit; the at least one first pixel unit circuit is electrically connected to the first sub-electrode of the at least one identification unit, respectively; the at least one second pixel unit circuit is electrically connected to the third sub-electrode of the at least one control unit, respectively; each of the at least one first pixel unit circuit and the at least one second pixel unit circuit includes a first voltage input terminal, a voltage output terminal, a driving transistor and a first unidirectional conduction circuit; the first unidirectional conduction circuit includes a first terminal and a second terminal, and the conduction direction of the first unidirectional conduction circuit is from the first terminal of the first unidirectional conduction circuit to the second terminal of the first unidirectional conduction circuit; the control terminal of the driving transistor and the second terminal of the first unidirectional conduction circuit are both connected to the voltage input terminal, the voltage output terminal, the driving transistor and the first unidirectional conduction circuit. The output end is electrically connected; the first end of the first unidirectional conduction circuit and the first voltage input end are both electrically connected to the first node; the voltage output end of the at least one first pixel unit circuit is electrically connected to the first sub-electrode; the driving transistor of the at least one first pixel unit circuit is configured to be electrically connected to the first power supply end and to convert the voltage signal on the first sub-electrode into a current signal; the voltage output end of the at least one second pixel unit circuit is electrically connected to the third sub-electrode; the at least one first pixel unit circuit also includes a second voltage input end, and the second voltage input end of the at least one first pixel unit circuit can be electrically connected to the first node; the seventh routing is electrically connected to the second voltage input end of the at least one first pixel unit circuit; and the eighth routing is electrically connected to the first voltage input end of the at least one first pixel unit circuit.

[0015] For example, in at least one example of the ultrasonic sensor, the ultrasonic sensor further includes a second unidirectional conduction circuit and a third unidirectional conduction circuit. The second unidirectional conduction circuit includes a third terminal and a fourth terminal, and the conduction direction of the second unidirectional conduction circuit is from the third terminal of the second unidirectional conduction circuit to the fourth terminal of the second unidirectional conduction circuit; the third unidirectional conduction circuit includes a fifth terminal and a sixth terminal, and the conduction direction of the third unidirectional conduction circuit is from the fifth terminal of the third unidirectional conduction circuit to the sixth terminal of the third unidirectional conduction circuit; the third terminal of the second unidirectional conduction circuit is connected to the first node, and the fourth terminal of the second unidirectional conduction circuit is connected to the second power supply terminal; the fifth terminal of the third unidirectional conduction circuit is connected to the third power supply terminal, and the sixth terminal of the third unidirectional conduction circuit is connected to the first node; and the second voltage input terminal of the at least one first pixel unit circuit is connected to the fifth terminal of the third unidirectional conduction circuit.

[0016] At least one embodiment of the present disclosure further provides a display device, which includes a display panel and the ultrasonic sensor provided by at least one embodiment of the present disclosure; the display panel and the ultrasonic sensor are stacked in a direction perpendicular to the display device.

[0017] For example, in at least one example of the display device, the ultrasonic sensor is located on a non-luminous side of the display panel, and the display panel is an organic light emitting diode display panel or a quantum dot display panel.

[0018] At least one embodiment of the present disclosure also provides a method for preparing an ultrasonic sensor, the ultrasonic sensor comprising a texture recognition area and a control area, the control area being located on at least one side of the texture recognition area, the texture recognition area comprising at least one recognition unit, the control area comprising at least one control unit, the at least one recognition unit comprising a first dielectric material layer, and the at least one control unit comprising a second dielectric material layer. The method comprises: using the same material to form a first portion for the first dielectric material layer and a second portion for the second dielectric material layer; performing a polarization treatment on at least the first portion so that the first portion is converted into the first dielectric material layer having piezoelectric properties, and the second portion is formed into the second dielectric material layer. The piezoelectric strain constant of the first dielectric material layer is greater than the piezoelectric strain constant of the second dielectric material layer.

[0019] For example, in at least one example of the method for preparing the ultrasonic sensor, the polarization treatment of at least the first part includes: while performing the polarization treatment on the first part using a polarization device, shielding the second part so that the polarization degree of the second part is less than the polarization degree of the first part.

[0020] For example, in at least one example of the method for preparing the ultrasonic sensor, the method for preparing the ultrasonic sensor further includes: forming a first electrode layer and a second electrode layer. The first electrode layer includes a first sub-electrode of the at least one identification unit and a third sub-electrode of the at least one reference unit, and the second electrode layer includes a second sub-electrode of the at least one identification unit and a fourth sub-electrode of the at least one reference unit; and forming the first portion for the first dielectric material layer and the second portion for the second dielectric material layer using the same material includes: forming a dielectric material layer on the first electrode layer using the same material. The dielectric material layer is located between the first electrode layer and the second electrode layer, and includes the first portion and the second portion.

[0021] For example, in at least one example of the method for preparing the ultrasonic sensor, the polarization treatment of at least the first part includes: placing a stack of the first electrode layer, the dielectric material layer and the second electrode layer in a polarization device; allowing the polarization device to form a plasma to perform the polarization treatment on the first part; and applying a shielding voltage to the fourth sub-electrode to shield the plasma.

[0022] For example, in at least one example of the method for manufacturing the ultrasonic sensor, before or while the polarization device is allowed to form the plasma, the shielding voltage is applied to the fourth sub-electrode.

[0023] For example, in at least one example of the method for preparing the ultrasonic sensor, the ultrasonic sensor also includes a backplane, a first routing line and a second routing line, both of which are electrically connected to the fourth sub-electrode; the first routing line extends from a position electrically connected to the fourth sub-electrode to an edge of the backplane; an orthographic projection of an end of the second routing line on the backplane is spaced apart from the edge of the backplane; and applying the shielding voltage to the fourth sub-electrode includes: applying the shielding voltage to the fourth sub-electrode using the first routing line.

[0024] For example, in at least one example of the method for preparing the ultrasonic sensor, the shielding voltage is 10V-30V.

[0025] For example, in at least one example of the method for manufacturing the ultrasonic sensor, the polarization treatment of at least the first portion includes: applying a first voltage to the first sub-electrode and applying a second voltage to the second sub-electrode, wherein the voltage difference between the first voltage and the second voltage is greater than 1000V. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present disclosure, but are not intended to limit the present disclosure.

[0027] Figure 1A shows the arrangement of electric dipoles in a polyvinylidene fluoride film before and after polarization;

[0028] Figure 1B An example of using a polarization device to polarize a polyvinylidene fluoride film is shown;

[0029] Figure 1C A schematic flow chart of a method for preparing a piezoelectric sensor based on PVDF is shown;

[0030] Figure 2A is a cross-sectional schematic diagram of an ultrasonic-based fingerprint sensor;

[0031] Figure 2B yes Figure 2A A cross-sectional schematic diagram of the ultrasonic transmitting assembly shown;

[0032] Figure 2C yes Figure 2A A cross-sectional schematic diagram of the ultrasonic receiving assembly shown;

[0033] Figure 2D A schematic diagram showing the composition of an electrical signal output by an ultrasonic-based fingerprint sensor;

[0034] Figure 3A is a plan view schematic diagram of an ultrasonic sensor provided by at least one embodiment of the present disclosure;

[0035] Figure 3B is a cross-sectional schematic diagram of an ultrasonic sensor provided by at least one embodiment of the present disclosure;

[0036] Figure 3C is a plan view schematically showing first to fourth sub-electrodes of an ultrasonic sensor provided by at least one embodiment of the present disclosure;

[0037] Figure 3D is another plan view schematically showing the first to fourth sub-electrodes of the ultrasonic sensor provided by at least one embodiment of the present disclosure;

[0038] Figure 3E is another schematic plan view of the first to fourth sub-electrodes of the ultrasonic sensor provided by at least one embodiment of the present disclosure;

[0039] Figure 4AThe relationship between the strength of the useful signal of an ultrasonic sensor including a piezoelectric material and the piezoelectric strain constant of the piezoelectric material is shown;

[0040] Figure 4B is a plan view schematic diagram of another ultrasonic sensor provided by at least one embodiment of the present disclosure;

[0041] Figure 4C is a plan view of yet another ultrasonic sensor provided by at least one embodiment of the present disclosure;

[0042] Figure 4D is a schematic plan view of yet another ultrasonic sensor provided by at least one embodiment of the present disclosure;

[0043] Figure 5 A schematic diagram showing a first example of performing a polarization treatment on a partial area of ​​a polyvinylidene fluoride film according to at least one embodiment of the present disclosure;

[0044] Figure 6 A schematic plan view of a stack of a back plate, a first electrode layer, a dielectric material layer, and a second electrode layer provided by at least one embodiment of the present disclosure is shown;

[0045] Figure 7 Shown along Figure 6 The schematic plan view of the ultrasonic sensor after the back plate is cut by the cutting line shown;

[0046] Figure 8 is another cross-sectional schematic diagram of an ultrasonic sensor provided by at least one embodiment of the present disclosure;

[0047] Fig. 9 yes Figure 8 An exemplary circuit diagram of a pixel unit circuit electrically connected to an identification unit is shown;

[0048] Fig.10 Shows Fig. 9 A driving timing diagram of a pixel unit circuit electrically connected to the identification unit when the ultrasonic sensor is working;

[0049] Fig.11 yes Figure 8 An exemplary circuit diagram of a pixel unit circuit electrically connected to a control unit as shown;

[0050] Fig.12 is a cross-sectional schematic diagram of another ultrasonic sensor provided by at least one embodiment of the present disclosure;

[0051] Fig.13 Shows Fig.12 A pixel unit circuit of the ultrasonic sensor shown is electrically connected to the first sub-electrode;

[0052] Fig.14 Shows Fig.12 An exemplary circuit diagram of a pixel unit circuit of an ultrasonic sensor electrically connected to a third sub-electrode is shown;

[0053] Fig.15 An amplifier and an analog-to-digital converter provided by at least one embodiment of the present disclosure are shown;

[0054] Fig.16 A schematic diagram of an ultrasonic sensor provided by at least one embodiment of the present disclosure is shown;

[0055] Fig.17 A schematic diagram of an ultrasonic sensor provided by at least one embodiment of the present disclosure is shown;

[0056] Fig.18 is an exemplary flow chart of a method for preparing an ultrasonic sensor provided by at least one embodiment of the present disclosure;

[0057] Fig.19A is an exemplary cross-sectional view of a stacked structure of a backplane, a first electrode layer, a dielectric material layer, and a second electrode layer provided by at least one embodiment of the present disclosure;

[0058] Fig.19B is an exemplary diagram of a first example of a polarization processing method provided by at least one embodiment of the present disclosure;

[0059] Fig. 20 is an exemplary diagram of a second example of a polarization processing method provided by at least one embodiment of the present disclosure;

[0060] Fig.21 is another exemplary diagram of a second example of a polarization processing method provided by at least one embodiment of the present disclosure;

[0061] Fig. 22 is a schematic diagram of monitoring the quality of polarization-related parameters provided by at least one embodiment of the present disclosure;

[0062] Fig.23 An exemplary block diagram of a display device provided for at least one embodiment of the present disclosure; and

[0063] Fig.24 An exemplary structural diagram of a display device provided for at least one embodiment of the present disclosure; DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0065] Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with ordinary skills in the field to which the present disclosure belongs. "First", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, "include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0066] The inventors of the present disclosure have noticed in their research that polyvinylidene fluoride film (PVDF film) does not have piezoelectric properties before polarization. This is because the electric dipoles inside the unpolarized PVDF film are arranged in a disordered manner (see Figure 1A After the PVDF membrane is polarized, it has piezoelectric properties (for example, it can exhibit piezoelectric effect). This is because the purpose of polarizing the PVDF membrane is to make the electric dipole orientation inside the PVDF membrane tend to be uniform (that is, highly oriented, see Figure 1A The right picture shows that intrinsic piezoelectric response can be generated inside the PVDF membrane after polarization treatment.

[0067] For example, a polyvinylidene fluoride film may be polarized using a polarization device. Figure 1B An example of using a polarization device to polarize a polyvinylidene fluoride film is shown. Figure 1B As shown, the polarization device includes a vacuum chamber 301, a discharge electrode 302, a grid electrode 303, a substrate heater 304, a metal platform 305, a discharge power supply 306 (output voltage is 10 kV-50 kV), a grid power supply 307 (output voltage is 5 kV-40 kV) and an electrometer 308.

[0068] For example, Figure 1BThe polarization device shown is an in-situ polarization device. Figure 1B The polarization device shown exemplifies the principle of polarization treatment of a polyvinylidene fluoride film (PVDF film).

[0069] For example, the polyvinylidene fluoride film can be polarized by the following method. First, the PVDF film 311 arranged on the back plate 330 (including the substrate 331 and the circuit structure 332) is placed in a polarization device. Secondly, a high-voltage electric field is formed between the discharge electrode 302 and the grid electrode 303, so that the discharge electrode (that is, the high-voltage source electrode) can ionize the air in the surrounding environment of the discharge electrode and generate plasma; the generated plasma moves to the surface of the unpolarized PVDF film under the action of the potential difference between the discharge electrode (that is, the high-voltage source electrode) and the grid electrode, which, for example, forms an oxidized polarization group on the surface of the PVDF film, so that the disordered electric dipoles in the unpolarized PVDF film are oriented and arranged under the action of the high-voltage electric field, which makes the PVDF film polarized and has piezoelectric properties.

[0070] Figure 1C A schematic flow chart of a method for preparing a piezoelectric sensor (or ultrasonic sensor) based on PVDF is shown. Figure 1C As shown, the method for preparing a PVDF-based piezoelectric sensor (or ultrasonic sensor) includes the following steps S511 to S518 performed in sequence.

[0071] Step S511: preparing a PVDF film (ie, preparing an initial film).

[0072] Step S512: uniaxially stretching the PVDF film.

[0073] Step S513: performing high voltage polarization on the stretched PVDF film.

[0074] Step S514: making internal electrodes of the PVDF-based piezoelectric sensor.

[0075] Step S515: cutting the shape of the laminated structure used to make the PVDF-based piezoelectric sensor.

[0076] Step S516: performing edge processing on the stacked structure used to make the PVDF-based piezoelectric sensor.

[0077] Step S517: Lead out the external electrodes of the PVDF-based piezoelectric sensor.

[0078] Step S518: forming a protective film on the stacked structure used to make the PVDF-based piezoelectric sensor, thereby forming the PVDF-based piezoelectric sensor.

[0079] For example, in steps S511 to S518, step S513, that is, performing high voltage polarization on the stretched PVDF film, is a key process.

[0080] The inventors of the present disclosure have noticed in their research that current ultrasonic-based fingerprint sensors (e.g., using Figure 1C The signal-to-noise ratio of the electrical signal output by the PVDF-based piezoelectric sensor (made by the method shown in the figure) is low, which will lead to the problem that the fingerprint pattern obtained based on the above electrical signal is quite different from the real fingerprint (that is, the fingerprint restoration is poor or unclear). Figure 2A - Figure 2D is an exemplary illustration.

[0081] Figure 2A is a schematic cross-sectional view of an ultrasonic-based fingerprint sensor (e.g., an under-screen fingerprint imaging sensor). Figure 2A As shown, the ultrasonic-based fingerprint sensor includes an ultrasonic transmitting component 511 and an ultrasonic receiving component 512 which are stacked on each other.

[0082] Figure 2B yes Figure 2A The cross-sectional schematic diagram of the ultrasonic transmitting component 511 is shown, Figure 2C 2A is a cross-sectional schematic diagram of the ultrasonic receiving assembly 512. Figure 2B As shown, the ultrasonic transmitting component 511 includes a first electrode 531, a second electrode 533, and a first piezoelectric material layer 532 located between the first electrode 531 and the second electrode 533. For example, the ultrasonic receiving component 512 and the ultrasonic transmitting component 511 may have a similar structure. Figure 2C As shown, the ultrasonic receiving component 512 includes a third electrode 541 , a fourth electrode 543 , and a second piezoelectric material layer 542 located between the third electrode 541 and the fourth electrode 543 .

[0083] For example, Figure 2A As shown, the ultrasonic-based fingerprint sensor further includes a back plate 513, which is configured to provide an electrical signal to at least one of the ultrasonic emitting component 511 and the ultrasonic receiving component 512. In some examples, the ultrasonic emitting component 511 and the ultrasonic receiving component 512 may each have a back plate, which will not be described in detail herein. Figure 2A As shown, the ultrasonic-based fingerprint sensor further includes a protective layer 514 , and during operation, the user's finger contacts the protective layer 514 .

[0084] For example, in the ultrasonic wave generation stage, the ultrasonic wave transmitting component 511 is configured to transmit ultrasonic waves under the action of an alternating voltage; in the ultrasonic wave receiving stage, the ultrasonic wave receiving component 512 is configured to receive ultrasonic waves and convert the received ultrasonic waves into electrical signals.

[0085] Described below Figure 2A The working principle of the ultrasonic-based fingerprint sensor shown is that the ultrasonic transmitting component 511 reflects ultrasonic waves and the ultrasonic receiving component 512 converts the received ultrasonic waves into electrical signals.

[0086] For example, Figure 2B As shown, the first electrode 531 and the second electrode 533 included in the ultrasonic emitting component 511 are configured to receive an alternating voltage (AC voltage). For example, the voltage difference between the first electrode 531 and the second electrode 533 included in the ultrasonic emitting component 511 can be an AC voltage. For example, a ground voltage is provided to the first electrode 531, and an AC voltage is provided to the second electrode 533. For example, under the action of the AC voltage, the first piezoelectric material layer 532 will deform and vibrate. For example, the first piezoelectric material layer 532 vibrates in the direction opposite to the first electrode 531 and the second electrode 533, and then the ultrasonic emitting component 511 can generate and output ultrasonic waves.

[0087] like Figure 2A As shown, in operation, the ultrasonic wave generated by the ultrasonic emitting component 511 is transmitted toward the protective layer 514; when the sound wave is transmitted to the fingerprint in contact with the protective layer 514, it is reflected by the fingerprint. Figure 2A As shown, there is air 552 between the valley of the fingerprint and the protective layer, and the ridge of the fingerprint is in contact with the protective layer. Figure 2A As shown, the ridges and valleys of the fingerprint have different reflectivities to the ultrasonic wave generated by the ultrasonic wave transmitting component 511 and transmitted toward the finger skin 551, that is, the energy of the ultrasonic wave reflected by the ridges of the fingerprint is different from the energy of the ultrasonic wave reflected by the valleys of the fingerprint. Figure 2A As shown, the energy of the ultrasonic wave reflected by the ridge of the fingerprint is smaller than the energy of the ultrasonic wave reflected by the valley of the fingerprint.

[0088] like Figure 2AAs shown, during operation, the ultrasonic wave reflected by the fingerprint is incident on the ultrasonic receiving component 512, and causes the second piezoelectric material layer 542 of the ultrasonic receiving component 512 to vibrate (for example, vibrate in the direction opposite to the third electrode 541 and the fourth electrode 543); the second piezoelectric material layer 542 of the ultrasonic receiving component 512 converts the vibration into an electrical signal (for example, an AC voltage); since the reflection energy of the ridges and valleys of the fingerprint is different, the intensity of the ultrasonic wave incident on different regions of the ultrasonic receiving component 512 is different, and the vibration amplitude of different regions of the ultrasonic receiving component 512 is different. Correspondingly, the vibration amplitude of different regions of the second piezoelectric material layer 542 is different, and the intensity (for example, average intensity) of the electrical signal (AC voltage) output by different regions of the second piezoelectric material layer 542 is different; therefore, fingerprint recognition can be performed based on the intensity distribution of the output electrical signal (AC voltage). For example, after processing the electrical signal, an image of the valley ridge distribution of the fingerprint can be obtained.

[0089] The inventors of the present disclosure have noticed in their research that Figure 2A The piezoelectric strain constant D33 of the piezoelectric material (e.g., at least one of the first piezoelectric material layer 532 and the second piezoelectric material layer 542) in the ultrasonic-based fingerprint sensor shown is usually small. For example, in order to be able to integrate the ultrasonic-based fingerprint sensor into the display screen (that is, subject to the constraints of under-screen integration of the display), the piezoelectric material selected for the ultrasonic-based fingerprint sensor is mostly polyvinylidene fluoride (PVDF) film; due to related manufacturing process limitations, the piezoelectric strain constant D33 of the PVDF film is generally less than or equal to 25. This makes at least one of the intensity of the ultrasonic wave generated by the ultrasonic transmitting component 511 and the intensity of the AC voltage signal output by the ultrasonic receiving component 512 smaller, thereby making the signal used to characterize the valley ridge distribution in the electrical signal output by the ultrasonic-based fingerprint sensor weaker.

[0090] The inventors of the present disclosure also noticed in their research that the electrical signals received and processed by the electrical components of the ultrasonic fingerprint sensor or the electrical components of the fingerprint detection system including the ultrasonic fingerprint sensor (e.g., the detection circuit and the pixel unit circuit) inevitably contain noise. Therefore, the electrical signals received by the electrical components include useful signals (e.g., signals for characterizing valley-ridge distribution) and noise signals (RMS), and the noise signals include electrical noise caused by the pixel unit circuit and electrical noise caused by the detection circuit.

[0091] Figure 2D A schematic diagram showing the composition of an electrical signal output by an ultrasonic fingerprint sensor. Figure 2DAs shown, the electrical signal output by the ultrasonic fingerprint sensor includes system noise (including noise caused by the ultrasonic fingerprint sensor system or device), noise cited by random jitter, noise caused by device differences, noise corresponding to bias voltage (or static operating point voltage), and signal corresponding to reflected echo (ultrasound reflected by the fingerprint back to the ultrasonic fingerprint sensor), where only the signal corresponding to the reflected echo is a useful signal (e.g., a signal used to characterize valley ridge distribution). For example, the electrical signal output by the ultrasonic fingerprint sensor may also include noise caused by environmental factors (e.g., temperature changes).

[0092] Since the signal used to characterize the valley-ridge distribution in the electrical signal output by the ultrasonic fingerprint sensor is weak and the electrical signal received by the electrical component also includes a variety of noises, such as the electrical noise caused by the pixel unit circuit and the electrical noise caused by the detection circuit, Figure 2A The electrical signal output by the ultrasonic fingerprint sensor shown has a low signal-to-noise ratio, which may reduce the quality of the fingerprint image output by the ultrasonic fingerprint sensor (eg, poor fingerprint restoration and unclear fingerprint).

[0093] At least one embodiment of the present disclosure provides an ultrasonic sensor, a method for preparing an ultrasonic sensor, and a display device. The ultrasonic sensor includes a texture recognition area (e.g., a fingerprint recognition area or a palm print recognition area) and a control area. The control area is located on at least one side of the texture recognition area; the texture recognition area includes at least one recognition unit (e.g., a fingerprint recognition unit), and the control area includes at least one control unit; at least one recognition unit includes a first dielectric material layer (e.g., a piezoelectric material layer); at least one control unit includes a second dielectric material layer; the first dielectric material layer and the second dielectric material layer are made of the same material; the first dielectric material layer has piezoelectric properties; the piezoelectric strain constant of the first dielectric material layer is greater than the piezoelectric strain constant of the second dielectric material layer.

[0094] For example, by setting a control area on at least one side of a texture recognition area (e.g., a fingerprint recognition area or a palm print recognition area), and making the piezoelectric strain constant of the first dielectric material layer included in the recognition unit in the texture recognition area greater than the piezoelectric strain constant of the second dielectric material layer included in the control unit in the control area, when the electrical signal output by the recognition unit is subsequently processed, the electrical signal output by the control unit can be used as at least part of the noise in the electrical signal output by the recognition unit and deducted to obtain an electrical signal deducted from at least part of the noise. For example, the electrical signal deducted from at least part of the noise can be used for raw data or preprocessed data for subsequent processing (e.g., converting the electrical signal into a fingerprint image). For example, since the noise in the electrical signal deducted from at least part of the noise is reduced, it is possible to improve the quality (e.g., image clarity) of an image (e.g., fingerprint image) acquired based on the electrical signal deducted from at least part of the noise.

[0095] For example, compared with a solution in which no dielectric material layer (for example, a second dielectric material layer) is provided in the control area (for example, a dielectric material layer formed in the control area is removed using a patterning process), by making the piezoelectric strain constant of the first dielectric material layer in the texture recognition area greater than the piezoelectric strain constant of the second dielectric material layer in the control area, the electrical structure of the control area can be made more similar to the electrical structure of the texture recognition area, thereby making the noise value of the control unit closer to the noise value of the recognition unit, thereby further improving the quality of the image (for example, a fingerprint image) acquired based on the above-mentioned electrical signal after deducting at least part of the noise.

[0096] In some examples, the ultrasonic sensor is an ultrasonic-based fingerprint imaging sensor, and PVDF is used to form the piezoelectric material of the ultrasonic-based fingerprint imaging sensor. For example, by at least changing the design of the backplane circuit of the fingerprint recognition sensor (e.g., at least one of the wiring and pixel unit circuit included in the backplane), the electrode layer of the multiplexed sensor (e.g., at least one of the first electrode layer and the second electrode layer described below) can be used to polarize only the first part of the PVDF in the process of manufacturing the ultrasonic-based fingerprint imaging sensor, without actively polarizing the second part of the PVDF (e.g., omitting the polarization treatment of the second part of the PVDF), thereby making the piezoelectric properties of the first part of the PVDF greater than the piezoelectric properties of the second part of the PVDF, and forming the recognition unit of the sensor located in the texture recognition area (i.e., the area including the first part of the PVDF) and the control unit located in the control area (i.e., the area including the second part of the PVDF). For example, the PVDF included in the control unit does not have a piezoelectric effect, but has semiconductor properties, so the PVDF included in the control unit can neither emit ultrasonic signals nor convert received ultrasonic signals into electrical signals; however, the control unit can output the noise caused by the ultrasonic excitation signal (e.g., TX excitation signal) applied to the control area and the noise caused by other factors as an electrical signal, and the electrical signal output by the control unit can be used as at least part of the noise of the electrical signal output by the identification unit (e.g., coupling the control unit noise to the identification unit); thus, the difference between the electrical signal output by the identification unit and the electrical signal output by the control unit can be used as an electrical signal minus at least part of the noise, and used for subsequent processing (e.g., converting the electrical signal into a fingerprint image) of the original data or pre-processed data. For example, since the noise (e.g., electrical noise) in the electrical signal minus at least part of the noise is reduced, it is possible to improve the quality of the image (e.g., fingerprint image) acquired based on the electrical signal minus at least part of the noise.

[0097] For example, the sensor can output the above-mentioned electrical signal from which at least part of the noise has been deducted, and provide it to a processing device of a detection system (e.g., a fingerprint detection system) including the above-mentioned sensor, so that the processing device (e.g., a processor) can acquire an image (e.g., a fingerprint image) based on the above-mentioned electrical signal from which at least part of the noise has been deducted.

[0098] For example, by using the difference between the electrical signal output by the recognition unit and the electrical signal output by the control unit as the electrical signal with at least part of the noise subtracted, at least part of the system noise and random jitter noise of the sensor can be removed. For example, the above-mentioned system noise can be noise or interference caused by an electronic system or circuit (for example, at least one of a pixel unit circuit and a detection circuit). For example, in the case where the ultrasonic excitation electrical signal received by the recognition unit is jittered, the intensity of the ultrasonic wave output by the recognition unit is also jittered, and correspondingly, the electrical signal output by the recognition unit will also be jittered (assuming that other noises remain unchanged); by using the control unit to output the noise caused by the ultrasonic excitation signal applied to the control area and the noise caused by other factors in the form of an electrical signal, the quality (for example, the clarity of the image) of the image (for example, the fingerprint image) obtained based on the electrical signal with at least part of the noise subtracted can be improved.

[0099] For example, the ultrasonic fingerprint imaging sensor can be integrated into a display device and arranged on the non-display side of the display panel of the display device, that is, the ultrasonic fingerprint imaging sensor can be used as at least part of the under-screen fingerprint detection system. For example, by taking the difference between the electrical signal output by the recognition unit and the electrical signal output by the control unit as the electrical signal minus at least part of the noise, the system noise and random jitter of the received signal can be suppressed, and the system signal-to-noise ratio can be improved; for example, the circuit noise of the under-screen fingerprint detection system can be effectively reduced after post-processing of the circuit, thereby at least partially solving the current problem of low signal-to-noise ratio and poor fingerprint restoration of under-screen fingerprint recognition.

[0100] The following non-restrictive description of the sensor provided according to the embodiments of the present disclosure is given through several examples and embodiments. As described below, different features in these specific examples and embodiments can be combined with each other without conflicting with each other to obtain new examples and embodiments, and these new examples and embodiments also fall within the scope of protection of the present disclosure.

[0101] Figure 3A 1 is a schematic plan view of an ultrasonic sensor 100 provided by at least one embodiment of the present disclosure. For example, the ultrasonic sensor 100 may be implemented as a fingerprint sensor, for example, the fingerprint ultrasonic sensor 100 may be a fingerprint imaging sensor, a palm print imaging sensor or other applicable sensors.

[0102] It should be noted that, for the convenience of description, the ultrasonic sensor 100 provided in at least one embodiment of the present disclosure is exemplarily described below by taking the sensor implemented as a fingerprint imaging sensor as an example, but at least one embodiment of the present disclosure is not limited thereto.

[0103] For example, Figure 3AAs shown, the ultrasonic sensor 100 includes a texture recognition area 101 and a control area 102, and the control area 102 is located at least on one side of the texture recognition area 101; the texture recognition area 101 includes at least one recognition unit 110, and the control area 102 includes at least one control unit 120. For example, the texture recognition area 101 and the control area 102 are arranged side by side in the first direction D1. For example, the control area 102 can include a first sub-control area 1021 and a second sub-control area 1022.

[0104] For example, Figure 3A As shown, the texture recognition area 101 includes a plurality of recognition units 110, and the plurality of recognition units 110 are arranged in an array, for example. Figure 3A As shown, the control area 102 includes a plurality of control units 120, which are arranged in one or more columns. For example, the fingerprint image can be acquired based on at least the electrical signals output by at least some of the identification units 110.

[0105] For example, the center spacing between adjacent recognition units 110 in the same texture recognition area 101 is 60-90 microns (e.g., 75 microns), and the center spacing between adjacent recognition units 110 and control units 120 is greater than or equal to the center spacing between adjacent recognition units 110 in the same texture recognition area 101. For example, when the center spacing between adjacent recognition units 110 in the same texture recognition area 101 is 75 microns, the center spacing between adjacent recognition units 110 and control units 120 is greater than or equal to 75 microns.

[0106] For example, at least one (eg, each) of the plurality of identification units 110 includes a first dielectric material layer 111 ( Figure 3A Not shown, see Figure 3B ); at least one (eg, each) of the plurality of control units 120 includes a second dielectric material layer 121 ( Figure 3A Not shown, see Figure 3B ).

[0107] In some examples, the identification unit 110 can be used to transmit ultrasonic waves, and can also convert ultrasonic waves reflected by fingerprints and incident on the above-mentioned laminated structure into electrical signals. For example, the first dielectric material layer 111 converts the voltage loaded on the first dielectric material layer 111 into mechanical motion based on the piezoelectric effect to generate ultrasonic waves; the first dielectric material layer 111 converts the mechanical motion caused by the ultrasonic waves reflected by the fingerprint to be detected and incident on the identification unit 110 into electrical signals based on the piezoelectric effect. For example, the above-mentioned identification unit 110 realizes the functions of transmitting ultrasonic waves and converting ultrasonic waves into electrical signals in a time-sharing manner. For example, since the second dielectric material layer 121 of the control unit 120 is not polarized or the degree of polarization is small, the control unit 120 cannot convert the ultrasonic waves incident on the control unit 120 into electrical signals (useful signals), or converts the ultrasonic waves incident on the control unit 120 into weak electrical signals (useful signals). Therefore, the electrical signal output by the control unit 120 is mainly noise.

[0108] Figure 3B is a cross-sectional schematic diagram of an ultrasonic sensor 100 provided by at least one embodiment of the present disclosure. Figure 3B As shown, at least one fingerprint recognition unit 110 also includes a first sub-electrode 112 and a second sub-electrode 113, and the first dielectric material layer 111 is sandwiched between the first sub-electrode 112 and the second sub-electrode 113 in a direction perpendicular to the ultrasonic sensor 100; at least one control unit 120 also includes a third sub-electrode 122 and a fourth sub-electrode 123; the second dielectric material layer 121 is sandwiched between the third sub-electrode 122 and the fourth sub-electrode 123 in a direction perpendicular to the ultrasonic sensor 100 (i.e., the third direction D3).

[0109] For example, Figure 3B As shown, the first dielectric material layer 111 and the second dielectric material layer 121 are located in the same layer; the first sub-electrode 112 and the third sub-electrode 122 are located in the same layer (for example, the first electrode layer); the second sub-electrode 113 and the fourth sub-electrode 123 are located in the same layer (for example, the second electrode layer).

[0110] For example, the first dielectric material layer 111 and the second dielectric material layer 121 are located in the same layer, which means that the first dielectric material layer 111 and the second dielectric material layer 121 are formed of the same material in the same patterning process, and the first dielectric material layer 111 and the second dielectric material layer 121 are in contact with the same film layer. For example, other "located in the same layer" involved in at least one embodiment of the present disclosure also have the same or similar features, which are not described in detail.

[0111] For example, by locating the first dielectric material layer 111 and the second dielectric material layer 121 in the same layer, the first sub-electrode 112 and the third sub-electrode 122 in the same layer, and the second sub-electrode 113 and the fourth sub-electrode 123 in the same layer, the electrical structures of the pattern recognition area 101 and the control area 102 can be made closer, thereby making the noise value of at least one recognition unit 110 closer to the noise value of at least one control unit 120, and further improving the quality of the image (for example, fingerprint image) obtained based on the above-mentioned electrical signal after deducting at least part of the noise.

[0112] For example, Figure 3B As shown, in the case where the texture recognition area 101 includes a plurality of recognition units 110, the first dielectric material layers 111 included in the plurality of recognition units 110 may be connected to each other (for example, there is no interface between the first dielectric material layers 111 included in adjacent recognition units 110), the first sub-electrodes 112 included in the plurality of recognition units 110 are spaced apart from each other, and the second sub-electrodes 113 included in the plurality of recognition units 110 are spaced apart from each other, but the embodiments of the present disclosure are not limited thereto.

[0113] For example, Figure 3B As shown, in the case where the control area 102 includes a plurality of control units 120, the second dielectric material layers 121 included in the plurality of control units 120 may be connected to each other (for example, no interface exists between the second dielectric material layers 121 included in adjacent control units 120), the third sub-electrodes 122 included in the plurality of control units 120 are spaced apart from each other, and the fourth sub-electrodes 123 included in the plurality of control units 120 are spaced apart from each other, but the embodiments of the present disclosure are not limited thereto.

[0114] In one example, if Figure 3C As shown, the second sub-electrodes 113 included in the multiple identification units 110 can also be connected to each other, that is, there is no interface or seam between the adjacent second sub-electrodes 113 and they are electrically connected to each other, thereby reducing the number of wirings; in this case, the second sub-electrodes 113 included in the multiple identification units 110 constitute a complete first common electrode 101; the orthographic projection of the first common electrode 101 on the backplane overlaps at least partially with the orthographic projection of the first sub-electrodes 112 included in the multiple identification units 110 on the backplane. For example, the orthographic projection of the first common electrode 101 on the backplane completely covers the orthographic projection of the first sub-electrodes 112 included in the multiple (for example, all) identification units 110 on the backplane.

[0115] In the above example, if Figure 3CAs shown, the fourth sub-electrodes 123 included in the multiple control units 120 located in the same sub-control area (for example, the first sub-control area 1021, the second sub-control area 1022) can also be connected to each other, that is, there is no interface or seam between the adjacent fourth sub-electrodes 123; and they are electrically connected to each other, thereby reducing the number of wiring; in this case, the fourth sub-electrodes 123 included in the multiple control units 120 in the sub-control area (for example, the first sub-control area 1021 and the second sub-control area 1022) constitute a complete second common electrode (for example, the second common electrodes 1231 and 1232); the orthographic projection of the second common electrode 1231 on the backplane overlaps at least partially with the orthographic projection of the third sub-electrodes 122 included in the multiple control units 120 in the corresponding sub-control area on the backplane. For example, the orthographic projection of the second common electrode 1231 on the backplane completely covers the orthographic projection of the third sub-electrodes 122 included in the multiple (for example, all) control units 120 in the corresponding sub-control area on the backplane.

[0116] In another example, Figure 3D As shown, the second sub-electrodes 113 included in the multiple identification units 110 can also be connected to each other, and the fourth sub-electrodes 123 included in the multiple control units 120 located in the same sub-control area (for example, the first sub-control area 1021, the second sub-control area 1022) can also be connected to each other, and the second sub-electrode 113 and the adjacent fourth sub-electrode 123 are connected to each other, that is, the second sub-electrodes 113 included in the multiple identification units 110 and the fourth sub-electrodes 123 included in the multiple control units 120 together form a complete common electrode 1133. For example, the orthographic projection of the common electrode 1133 on the backplane completely covers the orthographic projection of the first sub-electrodes 112 included in the multiple (for example, all) identification units 110 on the backplane and the orthographic projection of the third sub-electrodes 122 included in the multiple (for example, all) control units 120 on the backplane.

[0117] In another example, the fourth sub-electrodes 123 included in multiple control units 120 located in the same sub-control area (for example, the first sub-control area 1021, the second sub-control area 1022) are connected to each other, and the second sub-electrodes 113 included in adjacent identification units 110 are spaced apart from each other.

[0118] In yet another example, Figure 3EAs shown, the second sub-electrodes 113 of two adjacent (for example, two adjacent in the column direction) identification units 110 in the texture identification area 101 are connected to each other, and the fourth sub-electrodes 123 included in the two adjacent control units 120 in the sub-control area are connected to each other. For example, the orthographic projection of the electrode formed by the second sub-electrodes 113 included in the two adjacent (for example, two adjacent in the column direction) identification units 110 connected to each other on the backplane completely covers the orthographic projection of the first sub-electrodes 112 included in the above two adjacent identification units 110 on the backplane. For example, the orthographic projection of the electrode formed by the fourth sub-electrodes 123 included in the two adjacent control units 120 on the backplane completely covers the orthographic projection of the third sub-electrodes 122 included in the above two adjacent control units 120 on the backplane.

[0119] In yet another example, the second sub-electrodes 113 of three, four or other applicable numbers of recognition units 110 adjacent to each other (for example, adjacent in the column direction or row direction) in the texture recognition area 101 are connected to each other, and the fourth sub-electrodes 123 included in three, four or other applicable numbers of control units 120 adjacent to each other (for example, adjacent in the column direction or row direction) in the sub-control area are connected to each other. For example, the orthographic projection of the electrode formed by the second sub-electrodes 113 included in the adjacent three, four or other applicable numbers of recognition units 110 connected to each other on the backplane completely covers the orthographic projection of the first sub-electrodes 112 included in the adjacent three, four or other applicable numbers of recognition units 110 on the backplane. For example, the orthographic projection of the electrode formed by the fourth sub-electrodes 123 included in the adjacent three, four or other applicable numbers of control units 120 connected to each other on the backplane completely covers the orthographic projection of the third sub-electrode 122 included in the adjacent three, four or other applicable numbers of control units 120 on the backplane, which will not be repeated.

[0120] For example, the first dielectric material layer 111 has piezoelectric properties (e.g., piezoelectric effect); in this case, the first dielectric material layer 111 can also be referred to as a piezoelectric material layer. For example, because the first dielectric material layer 111 has piezoelectric properties (e.g., piezoelectric effect), when it is deformed by an external force (e.g., when receiving ultrasonic waves reflected by a fingerprint), the opposite surfaces of the first dielectric material layer 111 (e.g., the first dielectric material layer 111 at Figure 3B The first dielectric material layer 111 has two surfaces facing each other in the third direction (shown in FIG. 1 ), which have charges of opposite signs. That is, the first dielectric material layer 111 can convert the received ultrasonic signal into an electrical signal. Since the number of charges on the surface of the first dielectric material layer 111 is related to the magnitude of the external force (for example, the intensity of the ultrasonic wave reflected by the fingerprint), the intensity of the ultrasonic wave incident on the first dielectric material layer 111 can be obtained by collecting the charges on the opposite surfaces of the first dielectric material layer 111. For example, the first dielectric material layer 111 is Figure 3B The two surfaces opposite to each other in the third direction shown are in direct contact with the first sub-electrode 112 and the second sub-electrode 113 respectively. In this case, the charge generated by the first dielectric material layer 111 can be collected via at least one of the first sub-electrode 112 and the second sub-electrode 113 (for example, via the first sub-electrode 112) as the electrical signal output by the identification unit 110.

[0121] For example, the piezoelectric strain constant of the first dielectric material layer 111 is greater than the piezoelectric strain constant of the second dielectric material layer 121; for example, the larger the piezoelectric strain constant of the dielectric material, the greater the response of the dielectric material to the pressure applied thereto, that is, when the force applied to the dielectric material remains unchanged, the larger the piezoelectric strain constant of the dielectric material, the greater the amount of charge generated by the dielectric material, and correspondingly, the greater the intensity of the useful signal in the electrical signal output by the dielectric material. Therefore, by making the piezoelectric strain constant of the first dielectric material layer 111 in the texture recognition area 101 greater than the piezoelectric strain constant of the second dielectric material layer 121 in the control area 102, the strength of the useful signal in the electrical signal output by the recognition unit 110 can be made greater than the strength of the useful signal in the electrical signal output by the control unit 120; in this case, when the electrical signal output by the recognition unit 110 is subsequently processed, the electrical signal output by the control unit 120 can be used as at least part of the noise in the electrical signal output by the recognition unit 110 and deducted to obtain the electrical signal deducted from at least part of the noise and reduce the noise in the electrical signal output by the recognition unit 110. For example, the electrical signal deducted from at least part of the noise can be used for the original data or pre-processed data of subsequent processing (for example, converting the electrical signal into a fingerprint image). For example, since the noise in the electrical signal deducted from at least part of the noise is reduced, it is possible to improve the quality of the image (for example, fingerprint image) obtained based on the electrical signal deducted from at least part of the noise.

[0122] For example, the signal-to-noise ratio SNR of the electrical signal after deducting at least part of the noise is SNR=SS / SN, where SS is a useful signal in the electrical signal output by the recognition unit 110, and the electrical signal output by the recognition unit 110 can be transmitted via the fifth wiring 145 electrically connected to the first sub-electrode 112 (see below). Figure 7) is read. For example, the useful signal in the electrical signal after deducting at least part of the noise can be used as the useful signal in the electrical signal output by the recognition unit 110. SN is SS is the noise signal in the electrical signal after deducting at least part of the noise, and the noise signal in the electrical signal after deducting at least part of the noise is equal to the difference between the noise signal in the texture recognition area 101 and the noise signal in the control area 102. For example, the noise signal of the control area 102 can be obtained based on the electrical signal output by the control unit 120. For example, the electrical signal output by the control unit 120 can be obtained via the sixth wiring 146 electrically connected to the third sub-electrode 122 (see below). Figure 7 ) to read.

[0123] For example, if the electrical signal output by the control unit 120 is sufficiently close to the noise in the electrical signal output by the identification unit 110, the noise signal SS in the electrical signal after deducting at least part of the noise is close to zero; in this case, even if the control unit 120 has weak piezoelectric characteristics and generates a small amount of useful signal, since SN approaches zero, the signal-to-noise ratio SNR of the electrical signal after deducting at least part of the noise may also meet the actual application requirements.

[0124] For example, the inventors of the present disclosure have noticed through testing that the signal-to-noise ratio can be improved by providing a control area 102 on at least one side of the texture recognition area 101 , which is exemplarily described below.

[0125] For example, through testing, the inventors of the present disclosure noticed that the valley-ridge signal amount of the 8 columns of identification units 110 included in the sensor sample is about 400, and the noise is about 30. In this case, the signal-to-noise ratio is about 13; if the output electrical signal of the 4 columns of identification units 110 included in the sensor sample is subtracted from the output electrical signal of the adjacent 4 columns of control units 120 (for example, the average value of the electrical signal), and the noise signal in the electrical signal after deducting at least part of the noise becomes 20, then the signal-to-noise ratio increases to about 20. Therefore, the signal-to-noise ratio can be improved by setting a control area 102 on at least one side of the texture recognition area 101.

[0126] In one example, the second dielectric material layer 121 may not have piezoelectric properties (for example, piezoelectric effect), that is, the piezoelectric strain constant of the second dielectric material layer 121 is zero; correspondingly, after receiving the ultrasonic signal (that is, after being subjected to pressure), the second dielectric material layer 121 does not convert the ultrasonic signal into an electrical signal (that is, it cannot generate charges of opposite signs on the surfaces of the second dielectric material layer 121 that are opposite in the third direction); in this case, the intensity of the useful signal of the electrical signal output by the control unit 120 is zero, that is, the electrical signals output by the control unit 120 are all noise signals; in this case, after the electrical signal output by the control unit 120 is taken as at least part of the noise in the electrical signal output by the identification unit 110 and is deducted, the intensity of the useful signal (for example, a useful signal that can be used to characterize the valley-ridge distribution) in the electrical signal obtained after deducting at least part of the noise does not decrease, thereby improving the quality of the image (for example, a fingerprint image) obtained based on the electrical signal after deducting at least part of the noise.

[0127] It should be noted that the piezoelectric strain constant of the second dielectric material layer 121 is not limited to being equal to zero. The inventors of the present disclosure have noticed in their research that even if the piezoelectric strain constant of the second dielectric material layer 121 is not equal to zero, when the ratio of the piezoelectric strain constant of the first dielectric material layer 111 to the piezoelectric strain constant of the second dielectric material layer 121 is greater than or equal to 2 (for example, greater than or equal to 2.5), the ultrasonic sensor 100 provided by at least one embodiment of the present disclosure can improve the quality of the image (for example, fingerprint image) acquired based on the electrical signal after deducting at least part of the noise. Figure 4A An exemplary description is given.

[0128] Figure 4A The figure shows the relationship between the intensity of the useful signal of the ultrasonic sensor 100 including the piezoelectric material (the amount of charge corresponding to the useful signal) and the piezoelectric strain constant D33 of the piezoelectric material.

[0129] For example, Figure 4A As shown in FIG. 1 , the intensity of the useful signal of the ultrasonic sensor 100 including the piezoelectric material (the amount of charge corresponding to the useful signal) is exponentially related to the value of the piezoelectric strain constant D33 of the piezoelectric material. Figure 4A As shown, when the piezoelectric strain constant D33 of the piezoelectric material is 25 and 10 respectively, the amount of charge output by the ultrasonic sensor 100 including the piezoelectric material is 1160 and 61 respectively. In this case, the ratio of the amount of charge output by the ultrasonic sensor 100 including the piezoelectric material with D33 equal to 25 to the amount of charge output by the ultrasonic sensor 100 including the piezoelectric material with D33 equal to 10 is approximately equal to 19.

[0130] Therefore, when the ratio of the piezoelectric strain constant of the first dielectric material layer 111 to the piezoelectric strain constant of the second dielectric material layer 121 is greater than or equal to 2 (for example, greater than or equal to 2.5), the intensity of the useful signal in the electrical signal output by the control unit 120 is small (for example, can be ignored), and the ultrasonic sensor 100 provided by at least one embodiment of the present disclosure can improve the quality of the image (for example, the fingerprint image) acquired based on the above-mentioned electrical signal after deducting at least part of the noise.

[0131] For example, Figure 3A and Figure 3B As shown, the control area 102 may include a first sub-control area 1021 and a second sub-control area 1022; the first sub-control area 1021 and the second sub-control area 1022 are located on both sides of the texture recognition area 101 in the first direction D1. Figure 3A and Figure 3B As shown, in the case where the control area 102 includes the first sub-control area 1021 and the second sub-control area 1022, the electrical signals output by the multiple control units 120 included in the first sub-control area 1021 can be used as at least part of the noise value of the recognition unit 110 located in the left half of the texture recognition area, and the electrical signals output by the multiple control units 120 included in the second sub-control area 1022 can be used as at least part of the noise value of the recognition unit 110 located in the right half of the texture recognition area; because the electrical signals output by the multiple control units 120 included in the first sub-control area 1021 are closer to the noise value of the recognition unit 110 located in the left half of the texture recognition area, and the electrical signals output by the multiple control units 120 included in the second sub-control area 1022 are closer to the noise value of the recognition unit 110 located in the right half of the texture recognition area, therefore, by making the first sub-control area 1021 and the second sub-control area 1022 located in the first direction D1 of the texture recognition area 101 On both sides, the quality of the image (e.g., fingerprint image) obtained based on the electrical signal after deducting at least part of the noise can be further improved. For example, the electrical signal output by the comparison unit 120 located in the xth row of the first sub-comparison area 1021 is used as at least part of the noise value of the recognition unit 110 located in the left half of the xth row of the pattern recognition area, where multiple recognition units 110 are arranged in m rows, and multiple comparison units 120 are arranged in m rows.

[0132] For example, the first direction D1 may be the row direction of the ultrasonic sensor 100, and the second direction D2 may be the row direction of the ultrasonic sensor 100; when the ultrasonic sensor 100 is working, the recognition units 110 located in different rows sequentially output electrical signals formed by converting ultrasonic waves, that is, along the column direction of the ultrasonic sensor 100, the plurality of recognition units 110 output electrical signals row by row. For example, the first direction D1, the second direction D2, and the third direction D3 intersect each other (e.g., are perpendicular).

[0133] For example, for Figure 3A In the example shown, the texture recognition area 101 may include nine recognition units 110, each of the first sub-control area 1021 and the second sub-control area 1022 includes three control units 120, the nine recognition units 110 are arranged in a 3×3 array, and each of the first sub-control area 1021 and the second sub-control area 1022 includes three control units 120 arranged in a row.

[0134] It should be noted that the ultrasonic sensor 100 provided in at least one embodiment of the present disclosure is not limited to having one texture recognition area 101 and two sub-control areas, the number of recognition units 110 included in the texture recognition area 101 is not limited to nine, the number of control units 120 included in the sub-control area is not limited to three, and the control units 120 included in the sub-control area are not limited to being arranged in a row. The number of texture recognition areas 101 and sub-control areas included in the ultrasonic sensor 100, the number of recognition units 110 included in the texture recognition area 101, the number of control units 120 included in the sub-control area, and the arrangement of the control units 120 can be set according to actual application requirements. Figure 4B-4D An exemplary description is given.

[0135] Figure 4B FIG. 1 is a schematic plan view of another ultrasonic sensor 100 provided by at least one embodiment of the present disclosure. Figure 4B As shown, the ultrasonic sensor 100 includes a texture recognition area 101, and the control area 102 includes a sub-control area. The number of recognition units 110 included in the texture recognition area 101 is equal to (N+2)×(N+2); the number of control units 120 included in the sub-control area is equal to (N+2)×(N+2); here, N is a positive integer.

[0136] Figure 4C FIG. 1 is a schematic plan view of another ultrasonic sensor 100 provided by at least one embodiment of the present disclosure. Figure 4C As shown, the ultrasonic sensor 100 includes a texture recognition area 101, and the control area 102 includes a sub-control area. The number of recognition units 110 included in the texture recognition area 101 is equal to 16×20=320; the number of control units 120 included in the sub-control area is equal to 4×20=80.

[0137] Figure 4D FIG. 1 is a schematic plan view of yet another ultrasonic sensor 100 provided by at least one embodiment of the present disclosure. Figure 4DAs shown, the ultrasonic sensor 100 includes a plurality of texture recognition areas 101 (for example, two) and a plurality of sub-control areas (three). For example, the plurality of texture recognition areas 101 and the plurality of sub-control areas are alternately arranged in the first direction D1, and each recognition unit 110 in each texture recognition area 101 can use the electrical signal output by a control unit 120 located in the same row as the recognition unit and closest to the recognition unit or the average value of the electrical signals output by the plurality of control units 120 as at least part of the noise value of the recognition unit 110, thereby making the noise value of at least one recognition unit 110 closer to the deducted noise value, and further improving the quality of the image (for example, fingerprint image) obtained based on the electrical signal after deducting at least part of the noise.

[0138] It should be noted that Figure 4D The number of multiple texture recognition areas 101, the number of multiple sub-control areas, the number of columns of recognition units 110 included in each texture recognition area 101, and the number of columns of control units 120 included in each control area 102 are only examples, and those skilled in the art can set them according to actual application requirements.

[0139] For example, the pattern recognition area 101 and the control area 102 may have the same or similar electrical structures. For example, the first sub-electrode 112 and the third sub-electrode 122 have the same shape and size; the second sub-electrode 113 and the fourth sub-electrode 123 have the same shape and size; in this case, the electrical structures of the pattern recognition area 101 and the control area 102 can be made closer, thereby making the noise value of at least one recognition unit 110 closer to the noise value of the corresponding control unit 120 in at least one control unit 120, and further improving the quality of the image (e.g., fingerprint image) obtained based on the electrical signal with at least part of the noise deducted.

[0140] For example, the first dielectric material layer 111 and the second dielectric material layer 121 are both made of polyvinylidene fluoride film and have different polarization degrees. For example, by making the first dielectric material layer 111 and the second dielectric material layer 121 both made of the same material, the noise value of at least one identification unit 110 can be made closer to the noise value of at least one control unit 120. For example, when the piezoelectric strain constant of the first dielectric material layer 111 is greater than the piezoelectric strain constant of the second dielectric material layer 121, the polarization degree of the first dielectric material layer 111 is greater than the polarization degree of the second dielectric material layer 121 (for example, residual polarization intensity). For example, the residual polarization intensity of a dielectric material refers to the polarization intensity of a dielectric material when the dielectric material is not placed in an electric field and is not subjected to pressure. For example, the greater the degree of polarization of the dielectric material (e.g., residual polarization intensity), the greater the response of the dielectric material to the pressure applied thereto. That is, when the force applied to the dielectric material remains unchanged, the greater the degree of polarization of the dielectric material (e.g., residual polarization intensity), the greater the number of charges generated by the dielectric material, and correspondingly, the greater the intensity of the useful signal output by the dielectric material.

[0141] It should be noted that, although at least one embodiment of the present disclosure is exemplified by taking the first dielectric material layer 111 and the second dielectric material layer 121 as an example of being made of polyvinylidene fluoride film, at least one embodiment of the present disclosure is not limited thereto. For example, the first dielectric material layer 111 and the second dielectric material layer 121 can also be made of aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate piezoelectric ceramics (PZT) or other applicable piezoelectric materials.

[0142] For example, Figure 3B As shown, the ultrasonic sensor 100 further includes a back plate 130 ; an orthographic projection of the second dielectric material layer 121 on the back plate 130 and an orthographic projection of the first dielectric material layer 111 on the back plate 130 are spaced apart from each other. For example, by spacing the orthographic projection of the second dielectric material layer 121 on the back plate 130 and the orthographic projection of the first dielectric material layer 111 on the back plate 130 from each other, when the first dielectric material layer 111 is polarized using an electric field (e.g., a high voltage electric field), the influence of the electric field on the second dielectric material layer 121 can be reduced, so as to reduce the polarization degree of the second dielectric material layer 121 and the value of the piezoelectric strain constant D33 of the second dielectric material layer 121 after the polarization treatment (e.g., to avoid the second dielectric material layer 121 from being polarized); in this case, the intensity of the useful signal in the electrical signal output by the control unit 120 can be reduced, and the intensity of the useful signal in the electrical signal after at least part of the noise is deducted can be increased, thereby further improving the quality of the image (e.g., fingerprint image) acquired based on the above-mentioned electrical signal after at least part of the noise is deducted.

[0143] The following is an illustrative description of a scheme for forming the first dielectric material layer 111 and the second dielectric material layer 121 by actively polarizing only the region corresponding to the texture recognition region of the same dielectric material layer, with reference to two examples, but at least one embodiment of the present disclosure is not limited thereto.

[0144] In the first example, an unpolarized dielectric material layer (e.g., an unpolarized PVDF film) may be formed first, and then the first portion 146 of the dielectric material layer may be polarized using a polarization device, and while the first portion 146 of the dielectric material layer is polarized using the polarization device, a second portion 147 of the dielectric material layer may be shielded so that the polarization degree of the second portion 147 is less than the polarization degree of the first portion 146. Figure 5-Figure 11 An exemplary description is given.

[0145] Figure 5 FIG. 1 is a schematic diagram showing a first example of polarizing a partial region of a polyvinylidene fluoride film provided by at least one embodiment of the present disclosure. Figure 5 As shown, the polarization treatment of a partial area of ​​the polyvinylidene fluoride film may include the following steps.

[0146] Step S201: placing a stack of the back plate 130, the first electrode layer, the dielectric material layer (eg, an unpolarized PVDF film) and the second electrode layer in a polarization device.

[0147] For example, the first electrode layer includes a first sub-electrode 112 of at least one fingerprint recognition unit 110 and a third sub-electrode 122 of at least one control unit 120; the second electrode layer includes a second sub-electrode 113 of at least one fingerprint recognition unit 110 and a fourth sub-electrode 123 of at least one control unit 120; the dielectric material layer includes a first part 146 for the first dielectric material layer 111 and a second part 147 for the second dielectric material layer 121 formed using the same material (for example, PVDF); the backplane 130 includes a base substrate 131 and a circuit structure 132, and the circuit structure 132 of the backplane 130 is electrically connected to the first sub-electrode 112, the second sub-electrode 113, the third sub-electrode 122 and the fourth sub-electrode 123 through corresponding routings.

[0148] Step S202: A high voltage electric field is formed between the discharge electrode 302 and the grid electrode 303 of the polarization device to polarize the first portion 146 and convert the first portion 146 into a first dielectric material layer 111; and, before or while the polarization device forms plasma, a shielding voltage is applied to the fourth sub-electrode 123 to convert the second portion 147 into a second dielectric material layer 121.

[0149] For example, by applying a shielding voltage to the fourth sub-electrode 123, the potential difference between the upper surface and the lower surface of the second portion 147 can be made zero or very small (for example, insufficient to polarize the second portion 147), so that the high-voltage electric field formed between the discharge electrode 302 and the grid electrode 303 of the polarization device cannot polarize the second portion 147, or the polarization degree of the second portion 147 caused by the high-voltage electric field is less than the polarization degree of the first portion 146, so that the piezoelectric strain constant of the first dielectric material layer 111 is greater than the piezoelectric strain constant of the second dielectric material layer 121. For example, the ratio of the piezoelectric strain constant of the first dielectric material layer 111 to the piezoelectric strain constant of the second dielectric material layer 121 is greater than or equal to 2 (for example, greater than or equal to 2.5).

[0150] For example, by applying a shielding voltage (e.g., a ground voltage, e.g., 0V) to the fourth sub-electrode 123, an electron shielding layer can be formed at the point where the second portion 147 of the PVDF membrane located in the control area 102 contacts the ionized air, thereby making it so that there is no potential difference between the upper surface and the lower surface of the second portion 147 of the PVDF membrane located in the control area 102. In this case, no polarization electric field is formed between the upper surface and the lower surface of the second portion 147, and the second portion 147 of the PVDF membrane located in the control area 102 is not polarized. In some examples, although there is no potential difference between the upper surface and the lower surface of the second portion 147 of the PVDF membrane located in the control area 102, since the second portion 147 is located in the ionization field, electrons on both sides (e.g., the left and right sides) of the second portion 147 may also partially polarize the second portion 147. In this case, the piezoelectric strain constant D33 of the second portion 147 of the PVDF membrane located in the control area 102 is not equal to zero. However, as mentioned above, since the ratio of the piezoelectric strain constant of the first dielectric material layer 111 to the piezoelectric strain constant of the second dielectric material layer 121 is relatively large, the intensity of the useful signal in the electrical signal output by the control unit 120 is relatively small (eg, negligible).

[0151] For example, during the polarization process of the first portion 146, the first sub-electrode 112, the third sub-electrode 122 and the fourth sub-electrode 123 can be electrically connected to the ground terminal of the polarization device, and the second sub-electrode 113 located in the texture recognition area 101 can be suspended.

[0152] Figure 6 FIG. 4 shows a schematic plan view of a stack of a back plate 130, a first electrode layer, a dielectric material layer, and a second electrode layer provided by at least one embodiment of the present disclosure. Figure 7 Another schematic plan view of the stack of the backplane 130, the first electrode layer, the dielectric material layer, and the second electrode layer provided by at least one embodiment of the present disclosure is shown. Figure 6 Also shown are a first pad 151 (pad), a third pad 153, and a fourth pad 154 for applying a voltage to the first sub-electrode 112, the third sub-electrode 122, and the fourth sub-electrode 123 in a polarization treatment process.

[0153] For example, Figure 6 As shown, the ultrasonic sensor 100 also includes a first wiring 141 , which can be electrically connected to the fourth sub-electrode 123 , so that when the first portion 146 is polarized, a shielding voltage (eg, a ground voltage) can be applied to the fourth sub-electrode 123 via the first wiring 141 .

[0154] For example, Figure 6 As shown, the ultrasonic sensor 100 also includes a third line 143 and a fourth line 144, the third line 143 can be electrically connected to the first sub-electrode 112, and the fourth line 144 can be electrically connected to the third sub-electrode 122, so that when the first part 146 is polarized, a voltage (for example, a ground voltage) can be applied to the first sub-electrode 112 via the third line 143, and a voltage (for example, a ground voltage) can be applied to the third sub-electrode 122 via the fourth line 144.

[0155] For example, before the first part 146 is polarized, the first routing 141, the third routing 143 and the fourth routing 144 are electrically connected to the first pad 151, the third pad 153 and the fourth pad 154, respectively. Therefore, when the first part 146 is polarized, a shielding voltage (for example, a ground voltage) can be applied to the fourth sub-electrode 123 via the first pad 151 and the first routing 141, a voltage (for example, a ground voltage) can be applied to the first sub-electrode 112 via the third pad 153 and the third routing 143, and a voltage (for example, a ground voltage) can be applied to the third sub-electrode 122 via the fourth pad 154 and the fourth routing 144.

[0156] For example, Figure 6 As shown in FIG. 1 , after the polarization treatment of the first portion 146 is completed and the first portion 146 and the second portion 147 are respectively transformed into the first dielectric material layer 111 and the second dielectric material layer 121, the first portion 146 and the second portion 147 can be connected along the Figure 6 The cutting line 161 shown cuts the back plate 130, thereby removing the first pad 151, the third pad 153 and the fourth pad 154, that is, the first pad 151, the third pad 153 and the fourth pad 154 are not in the final product of the ultrasonic sensor 100. Figure 6 The schematic plan view of the ultrasonic sensor 100 after the back plate 130 is cut by the cutting line 161 is shown in FIG. Figure 7 shown.

[0157] For example, cutting the back plate 130 may refer to cutting the base substrate 131 (e.g., a glass substrate) included in the back plate 130. For example, by cutting off the first pad 151, the third pad 153, and the fourth pad 154, it is possible to prevent at least one of the first pad 151, the third pad 153, and the fourth pad 154 from having an adverse effect during the operation of the ultrasonic sensor 100.

[0158] For example, Figure 7 As shown, the first routing line 141 may extend from the position electrically connected to the fourth sub-electrode 123 to the edge of the back plate 130; the third routing line 143 may extend from the position electrically connected to the first sub-electrode 112 to the edge of the back plate 130; and the fourth routing line 144 may extend from the position electrically connected to the third sub-electrode 122 to the edge of the back plate 130.

[0159] For example, Figure 6 and Figure 7 As shown, the ultrasonic sensor 100 further includes a second wiring 142, a fifth wiring 145, and a sixth wiring 146; the second wiring 142 can be electrically connected to the fourth sub-electrode 123, and the orthographic projection of the end of the second wiring 142 on the back plate 130 is spaced from the edge of the back plate 130; the fifth wiring 145 can be electrically connected to the first sub-electrode 112, and the orthographic projection of the end of the fifth wiring 145 on the back plate 130 is spaced from the edge of the back plate 130; the sixth wiring 146 can be electrically connected to the third sub-electrode 122, and the orthographic projection of the end of the sixth wiring 146 on the back plate 130 is spaced from the edge of the back plate 130. For example, Figure 6 and Figure 7 As shown, the second routing 142 and the first routing 141 are electrically connected (eg, directly connected), the third routing 143 and the fifth routing 145 are electrically connected (eg, directly connected), and the fourth routing 144 and the sixth routing 146 are electrically connected (eg, directly connected).

[0160] In some examples, along the Figure 6 After the cutting line 161 shown cuts the back panel 130, the ultrasonic sensor 100 also includes the above-mentioned second pad 152, fifth pad 155 and sixth pad 156; the end of the second routing 142, the end of the fifth routing 145 and the end of the sixth routing 146 are electrically connected to the second pad 152, the fifth pad 155 and the sixth pad 156 respectively, so that during operation, the relevant driving circuit can provide electrical signals to the fourth sub-electrode 123, the first sub-electrode 112 and the third sub-electrode 122 via the second pad 152, the fifth pad 155 and the sixth pad 156 respectively.

[0161] For the sake of clarity, the specific implementation of the second routing line 142 , the fifth routing line 145 and the sixth routing line 146 will be described after describing the specific structure of the backplane 130 , and will not be repeated here.

[0162] Figure 8 is another cross-sectional schematic diagram of the ultrasonic sensor 100 provided by at least one embodiment of the present disclosure. Figure 3B A schematic cross-sectional view of an ultrasonic sensor 100 is shown. Figure 8 The schematic cross-sectional view of the ultrasonic sensor 100 shows an exemplary structure of the back plate 130 .

[0163] For example, Figure 8 As shown, the backplane 130 includes a substrate 131 and a circuit structure 132 stacked in a third direction. Figure 8 As shown, the circuit structure 132 includes a plurality of pixel unit circuits. For example, a first portion of the plurality of pixel unit circuits is configured to be electrically connected to at least one recognition unit 110 to apply a voltage to at least one recognition unit 110 and cause the recognition unit 110 to emit an ultrasonic wave, and to obtain an electrical signal (e.g., a current signal) from at least one recognition unit 110. For example, a second portion of the plurality of pixel unit circuits is configured to be electrically connected to at least one control unit 120 to apply a voltage to at least one control unit 120 and to obtain an electrical signal (e.g., a current signal) from at least one control unit 120.

[0164] In some examples, Figure 8 The structure of the pixel unit circuit electrically connected to the identification unit 110 and the structure of the pixel unit circuit electrically connected to the comparison unit 120 are shown.

[0165] Fig. 9 yes Figure 8 1 is an exemplary circuit diagram of a pixel unit circuit 133 electrically connected to the identification unit 110. For ease of description, Fig. 9 Also shown are a first sub-electrode 112 , a second sub-electrode 113 and a first dielectric material layer 111 included in the identification unit 110 , as well as a first terminal In_1 and a second terminal In_2 of the identification unit 110 .

[0166] For example, Fig. 9 As shown, the pixel unit circuit 133 includes a first voltage input terminal V_in (corresponding to Figure 8, a voltage output terminal V_out, a driving transistor M1 and a first unidirectional conduction circuit 181; the driving transistor M1 is configured to be electrically connected to the first power supply terminal Vdd and to convert the voltage signal on the first sub-electrode 112 into a current signal; the first unidirectional conduction circuit 181 includes a first end and a second end, and the conduction direction of the first unidirectional conduction circuit 181 is from the first end of the first unidirectional conduction circuit 181 to the second end of the first unidirectional conduction circuit 181; the control end of the driving transistor M1 and the second end of the first unidirectional conduction circuit 181 are both electrically connected to the voltage output terminal V_out; the first end of the first unidirectional conduction circuit 181 and the first voltage input terminal V_in are both electrically connected to the first node N1.

[0167] For example, Fig. 9 As shown, the first unidirectional conducting circuit 181 includes a first diode D1 , an anode terminal of the first diode D1 is configured as a first terminal of the first unidirectional conducting circuit 181 , and a cathode terminal of the first diode D1 is configured as a second terminal of the first unidirectional conducting circuit 181 .

[0168] For example, Fig. 9 As shown, the pixel unit circuit 133 also includes a first transistor M0 and a second transistor M2; the control terminal RST of the first transistor M0 is configured to receive a reset control signal, the first end of the first transistor M0 is configured to be electrically connected to the first node N1, and the second end of the first transistor M0 is configured to be electrically connected to the control end of the driving transistor M1; the first end of the driving transistor M1 is configured to be electrically connected to the first power supply terminal Vdd, and the second end of the driving transistor M1 is configured to be electrically connected to the first end of the second transistor M2; the control terminal GAT of the second transistor M2 is configured to receive a read control signal, and the second end of the second transistor M2 is configured as a signal output terminal C_out of the pixel unit circuit to output the electrical signal generated by the first dielectric material layer by converting ultrasonic waves.

[0169] It should be noted that Fig. 9 The first terminal In_1 and the second terminal In_2 of the identification unit 110 and the voltage output terminal V_out, the signal output terminal C_out, the control terminal RST of the first transistor M0 and the control terminal GAT of the second transistor M2 of the pixel unit circuit 133 are shown only for the convenience of description, and there is no need to set, for example, a solder joint or a pad as the first terminal In_1, the second terminal In_2, etc. in the actual product. For example, the first sub-electrode of the identification unit 110 is used as the second terminal In_2 to be electrically connected to the voltage output terminal V_out of the pixel unit circuit 133.

[0170] Fig.10 Shows Fig. 9The driving timing diagram of the pixel unit circuit 133 electrically connected to the recognition unit 110 when the ultrasonic sensor 100 is working. Fig. 9 and Fig.10 As shown, the working cycle of the ultrasonic sensor 100 includes an ultrasonic wave generating phase Tg and an ultrasonic wave receiving phase Tr.

[0171] For example, Fig. 9 and Fig.10 As shown, in the ultrasonic wave generation stage Tg, the reset control signal received by the control terminal of the first transistor M0 is a valid signal (that is, a signal or level that turns on the transistor), thereby turning on the first transistor M0, and the first voltage (for example, the ground voltage) provided by the first voltage input terminal V_in of the pixel unit circuit is transmitted to the control terminal of the driving transistor M1, the voltage output terminal V_out of the pixel unit circuit 133, and the first sub-electrode 112 of the identification unit 110 electrically connected to the voltage output terminal V_out of the pixel unit circuit 133 via the turned-on first transistor M0. For example, the first terminal In_1 and the second sub-electrode 113 of the identification unit 110 are configured to receive an alternating voltage, thereby the identification unit 110 is configured to perform mechanical vibration and generate ultrasonic waves in the ultrasonic wave generation stage Tg. For example, since the control terminal of the driving transistor M1 is closed under the action of the first voltage (for example, the ground voltage), the pixel unit circuit is not used to read the electrical signal on the first sub-electrode 112 in the ultrasonic wave generation stage Tg. For example, in the ultrasonic wave generation stage Tg, the read control signals received by the control terminals GAT of the second transistors M2 of the pixel unit circuits located in different rows are all invalid signals (that is, signals or levels that turn off the transistors; for example, low levels). Thus, the second transistors M2 of the pixel unit circuits located in different rows are all turned off.

[0172] For example, Fig. 9 and Fig.10 As shown, in the ultrasonic receiving stage Tr, the reset control signal received by the control terminal of the first transistor M0 is an invalid signal, so that the first transistor M0 is turned off; the second voltage (for example, bias voltage) provided by the first voltage input terminal V_in of the pixel unit circuit is transmitted to the control terminal of the driving transistor M1 via the first diode D1, so that the driving transistor M1 remains turned on in the ultrasonic receiving stage Tr; the control terminals GAT of the second transistors M2 of the pixel unit circuits located in different rows receive valid signals (for example, high level) in sequence, so that the second transistors M2 of the pixel unit circuits located in different rows are turned on in sequence, and the pixel unit circuits located in different rows output electrical signals in sequence.

[0173] Fig.11 yes Figure 8 1 is an exemplary circuit diagram of a pixel unit circuit 133 electrically connected to a control unit 120. For ease of description, Fig.11 The third sub-electrode 122, the fourth sub-electrode 123 and the second dielectric material layer 121 included in the identification unit 110 and the first terminal In_3 (corresponding to the first terminal In_4 of the control unit 120) are also shown. Figure 8 171) and the second end In_4.

[0174] It should be noted that Fig.11 The first end In_3 , the second end In_4 , etc. of the control unit 120 shown are only for convenience of description, and there is no need to set, for example, a welding point or a pad as the first end In_3 , the second end In_4 , etc. of the control unit 120 in an actual product.

[0175] For example, Fig.11 The driving timing diagram of the pixel unit circuit 133 electrically connected to the control unit 120 when the ultrasonic sensor 100 is working can be the same as Fig.10 The same, no further elaboration.

[0176] For example, Figure 8 and Fig.11 As shown, the first terminal 171 (In3) of the control unit 120 is electrically connected to the fourth sub-electrode 123, and can be electrically connected to the second pad 152 via the second wiring 142, so that when the ultrasonic sensor 100 is working, the AC voltage applied via the second pad 152 can be transmitted to the fourth sub-electrode 123 of the illumination unit 120 via the second wiring 142 and the first terminal 171 (In3) of the control unit 120. For example, the first voltage input terminal V_in (172) of the pixel unit circuit 133 electrically connected to the control unit 120 can be electrically connected to the sixth pad 156 via the sixth wiring 146, so that when the ultrasonic sensor 100 is working, the first voltage (for example, ground voltage) and the second voltage (for example, bias voltage) applied via the sixth pad 156 can be transmitted to the third sub-electrode 122 of the control unit 120 via the sixth wiring 146, the first voltage input terminal V_in (172) and the unidirectional conduction circuit 181.

[0177] For example, Figure 8 and Fig. 9 As shown, the first voltage input terminal V_in (172) of the pixel unit circuit 133 electrically connected to the identification unit 110 can be electrically connected to the fifth pad 155 via the fifth wiring 145. Thus, when the ultrasonic sensor 100 is working, the first voltage (for example, the ground voltage) and the second voltage (for example, the bias voltage) applied via the fifth pad 155 can be transmitted to the first sub-electrode 112 of the identification unit 110 via the fifth wiring 145, the first voltage input terminal V_in (172) and the unidirectional conduction circuit 181.

[0178] For example, Figure 6 and Figure 7 As shown, the first routing 141 is electrically connected to the second routing 142 (for example, directly connected), thereby the first routing 141 is electrically connected to the fourth sub-electrode 123 of the control unit 120; the fourth routing 144 is electrically connected to the sixth routing 146 (for example, directly connected), thereby the fourth routing 144 is electrically connected to the third sub-electrode 122 of the control unit 120; the third routing 143 is electrically connected to the fifth routing 145 (for example, directly connected), thereby the third routing 143 is electrically connected to the first sub-electrode 112 of the identification unit 110. In this case, when the polarization device is used to perform polarization processing on the first portion 146, a shielding voltage (for example, a ground voltage) can be applied to the fourth sub-electrode 123 of the control unit 120 via the first pad 151, the first wiring 141, at least a portion of the second wiring 142, and the first end 171 of the control unit 120, and a first voltage input terminal V_in of the pixel unit circuit 133 electrically connected to the control unit 120 can be applied to the fourth sub-electrode 123 of the control unit 120 via the fourth pad 154, the fourth wiring 144, at least a portion of the sixth wiring 146, and the first voltage input terminal V_in of the pixel unit circuit 133 electrically connected to the control unit 120. (172) A voltage (e.g., a ground voltage) is applied to the third sub-electrode 122 of the control unit 120, and a voltage (e.g., a ground voltage) is applied to the first sub-electrode 112 of the identification unit 110 via the third pad 153, the third wiring 143, at least a portion of the fifth wiring 145, and the first voltage input terminal V_in (172) of the pixel unit circuit 133 electrically connected to the identification unit 110, so that the fourth sub-electrode 123 of the control unit 120 can be reused as an electronic shielding layer during the polarization process of the first portion 146, thereby eliminating the need to set an additional electronic shielding layer on the dielectric material layer, and eliminating the need to remove the electronic shielding layer after the polarization process is completed, thereby simplifying the manufacturing process of the ultrasonic sensor 100. For example, since the patterning process of the electrode layer is relatively mature, the size accuracy and position accuracy of the fourth sub-electrode 123 are relatively high, thereby reducing the difficulty of alignment and simplifying the polarization process compared to using an electronic shielding layer that is separately set from the dielectric material layer.

[0179] In the second example, a non-polarized polyvinylidene fluoride film may be formed first, and then a voltage may be directly input to the first sub-electrode 112 and the second sub-electrode 113 via the back plate 130, so that a high voltage electric field exists between the two surfaces of the first portion 146 that are opposite to each other in the third direction, so as to polarize the first portion 146 and convert the first portion 146 into the first dielectric material layer 111, and convert the second portion 147 into the second dielectric material layer 121. For example, during the polarization process, the third sub-electrode 122 and the fourth sub-electrode 123 may both be suspended. Since a high voltage electric field is not formed between the two surfaces of the second portion 147 that are opposite to each other in the third direction, the polarization degree of the second portion 147 may be less than that of the first portion 146. Figure 12-16An exemplary description is given.

[0180] Fig.12 is a schematic cross-sectional view of another ultrasonic sensor 100 provided by at least one embodiment of the present disclosure. Fig.12 The ultrasonic sensor 100 shown is Figure 8 The ultrasonic sensors 100 shown are similar, and therefore, only the differences between the two are described herein, and the similarities are not repeated.

[0181] Fig.12 The ultrasonic sensor 100 shown is Figure 8 The differences between the ultrasonic sensor 100 shown include the following three points. (1) Fig.12 The second sub-electrode 113 of the ultrasonic sensor 100 is electrically connected to a different wiring than that of Figure 8 The wiring diagram of the second sub-electrode 113 of the ultrasonic sensor 100 is shown. Fig.12 The wiring for electrically connecting the fourth sub-electrode 123 of the ultrasonic sensor 100 is different from that of Figure 8 The wiring diagram of the fourth sub-electrode 123 of the ultrasonic sensor 100 is shown. (3) Fig.12 The pixel unit circuit (hereinafter referred to as the first pixel unit circuit 134) electrically connected to the first sub-electrode 112 of the ultrasonic sensor 100 is different from Figure 8 The pixel unit circuit of the ultrasonic sensor 100 shown is electrically connected to the first sub-electrode 112. Fig.12 The pixel unit circuit (hereinafter referred to as the second pixel unit circuit 135) electrically connected to the third sub-electrode 122 of the ultrasonic sensor 100 shown in FIG. Figure 8 The pixel unit circuit electrically connected to the third sub-electrode 122 of the ultrasonic sensor 100 shown in the figure has its wiring electrically connected to the first pixel unit circuit 134 changed accordingly.

[0182] Regarding the first difference mentioned above, Fig.12 The wiring electrically connected to the second sub-electrode 113 of the ultrasonic sensor 100 shown includes a ninth wiring 149 and a tenth wiring 1491; for example, Fig.12 As shown, the first end 171 of the identification unit 110 can be electrically connected to the ninth pad 159 via the ninth wiring 149, so that when the ultrasonic sensor 100 is working, the AC voltage applied via the ninth pad 159 can be transmitted to the second sub-electrode 113 of the identification unit 110. Fig.12As shown, the tenth wiring 1491 is electrically connected to the ninth wiring 149 (for example, directly connected), so that the first end 171 of the identification unit 110 can be connected to the tenth pad 1591 via the ninth wiring 149 and the tenth wiring 1491; in this case, when the first portion 146 is polarized, a voltage (for example, a negative high voltage, for example, negative 3 kV) can be applied to the second sub-electrode 113 of the identification unit 110 via the tenth pad 1591, the tenth wiring 1491, the ninth wiring 149 and the first end In_1 (174) of the identification unit 110. For example, with Figure 8 The routing lines electrically connected to the second sub-electrode 113 of the ultrasonic sensor 100 shown include only one routing line (eg, the ninth routing line 149 but not the tenth routing line 1491 ).

[0183] Regarding the second difference mentioned above, Fig.12 The wiring electrically connected to the fourth sub-electrode 123 of the ultrasonic sensor 100 shown only includes Figure 7 and Figure 8 The second trace 142 is shown, but the first trace 141 is not included.

[0184] Regarding the third difference mentioned above, Fig.13 Shows Fig.12 The pixel unit circuit (hereinafter referred to as the first pixel unit circuit 134 ) of the ultrasonic sensor 100 electrically connected to the first sub-electrode 112 is shown. Fig.14 Shows Fig.12 1 is an exemplary circuit diagram of a pixel unit circuit (hereinafter referred to as a second pixel unit circuit 135 ) of the ultrasonic sensor 100 that is electrically connected to the third sub-electrode 122 .

[0185] For example, compared to Fig. 9 The pixel unit circuit electrically connected to the first sub-electrode 112 is shown as Fig.12 and Fig.13 As shown, the first pixel unit circuit 134 also includes a second voltage input terminal V_in2; Fig.13 As shown, the second voltage input terminal V_in2 of the first pixel unit circuit 134 may be electrically connected to the first node N1. Fig.12 As shown, the seventh wiring 147 is connected to the second voltage input terminal V_in2 (corresponding to Fig.12 The eighth wiring 148 is electrically connected to the first voltage input terminal V_in (corresponding to the first pixel unit circuit 134) of the first pixel unit circuit; Fig.12 172) is electrically connected.

[0186] For example, Fig.12As shown, the seventh routing line 147 is electrically connected to the seventh pad 157 , and the eighth routing line 148 is electrically connected to the eighth pad 158 .

[0187] For example, when the first portion 146 is polarized, the seventh pad 157, the seventh wiring 147 and the second voltage input terminal V_in2 (corresponding to Fig.12 173) applies a voltage (e.g., a ground voltage) to the first sub-electrode 112 of the identification unit 110. For example, after the first portion 146 is polarized, the seventh pad 157 and the tenth pad 1591 may be cut off so that at least one of the seventh pad 157 and the tenth pad 1591 has an adverse effect on the operation of the ultrasonic sensor 100.

[0188] For example, after the seventh pad 157 and the tenth pad 1591 are cut off, the seventh routing line extends from the position electrically connected to the first sub-electrode to the edge of the back panel; the end of the eighth routing line has its orthographic projection on the back panel spaced from the edge of the back panel; the tenth routing line extends to the edge of the back panel, and the end of the ninth routing line 149 has its orthographic projection on the back panel spaced from the edge of the back panel.

[0189] For example, the ends of the eighth wiring 148 and the ninth wiring 149 are electrically connected to the eighth pad 158 and the ninth pad 159 respectively, so that during operation the relevant driving circuit can provide electrical signals to the first sub-electrode 112 and the second sub-electrode 113 via the eighth pad 158 and the ninth pad 159 respectively.

[0190] For example, the pixel unit circuit electrically connected to the first sub-electrode 112 further includes a second unidirectional conduction circuit 182 and a third unidirectional conduction circuit 183 . The second unidirectional conduction circuit 182 includes a third terminal and a fourth terminal, and the conduction direction of the second unidirectional conduction circuit 182 is from the third terminal of the second unidirectional conduction circuit 182 to the fourth terminal of the second unidirectional conduction circuit 182; the third unidirectional conduction circuit 183 includes a fifth terminal and a sixth terminal, and the conduction direction of the third unidirectional conduction circuit 183 is from the fifth terminal of the third unidirectional conduction circuit 183 to the sixth terminal of the third unidirectional conduction circuit 183; the third terminal of the second unidirectional conduction circuit 182 is connected to the first node N1, and the fourth terminal of the second unidirectional conduction circuit 182 is connected to the second power supply terminal Vcc to receive the voltage Vmax provided by the second power supply terminal; the fifth terminal of the third unidirectional conduction circuit 183 is connected to the third power supply terminal Vss to receive the voltage Vmin provided by the second power supply terminal, and the sixth terminal of the third unidirectional conduction circuit 183 is connected to the first node N1; the second voltage input terminal V_in2 of the first pixel unit circuit 134 is connected to the fifth terminal of the third unidirectional conduction circuit 183. For example, by providing the second unidirectional conduction circuit 182 and the third unidirectional conduction circuit 183, the identification unit 110 can be protected from overvoltage; for example, the voltage output by the identification unit 110 can be clamped between Vmin and Vmax. For example, Vmin = -20V, Vmax = 20V, in this case, the second unidirectional conduction circuit 182 and the third unidirectional conduction circuit 183 can clamp the voltage output by the identification unit 110 between ±20V.

[0191] For example, Fig.13 As shown, at least one (eg, each) of the second unidirectional conductive circuit 182 and the third unidirectional conductive circuit 183 may include a diode. Fig.13 As shown, at least one (for example, each) of the second unidirectional conduction circuit 182 and the third unidirectional conduction circuit 183 may include two diodes connected in series, but at least one embodiment of the present disclosure is not limited to this, and at least one of the second unidirectional conduction circuit 182 and the third unidirectional conduction circuit 183 may include other applicable numbers of diodes or other applicable unidirectional conduction circuits.

[0192] For example, Fig.14 As shown, Fig.14 The second pixel unit circuit 135 is shown with Fig.13 The first pixel unit circuit 134 is similar to the first pixel unit circuit 134 shown in FIG. 1 , except that the second pixel unit circuit 135 does not include Fig.13 The second voltage input terminal V_in2 and the corresponding wiring shown, therefore, Fig.14 The other structures of the second pixel unit circuit 135 are not described in detail.

[0193] It should be noted that Figure 8 The pixel unit circuit electrically connected to the first sub-electrode 112 and the pixel unit circuit electrically connected to the second sub-electrode 113 included in the ultrasonic sensor 100 shown in the figure may also be adopted. Fig.14 The second pixel unit circuit 135 may also adopt Fig.11 The circuit shown will not be described in detail here.

[0194] In some examples, the ultrasonic sensor 100 may further include an appropriate number of amplifiers AP and an appropriate number of analog-to-digital converters AD. Figure 15-17 An exemplary description is given.

[0195] Fig.15 1 shows an amplifier AP and an analog-to-digital converter AD provided by at least one embodiment of the present disclosure. Fig.15 As shown, the pixel unit circuit (for example, the second pixel unit circuit 135) is electrically connected to the signal input terminal of the amplifier AP to provide the electrical signal output by the pixel unit circuit to the signal input terminal of the amplifier AP; the reference signal terminal of the amplifier AP, for example, receives a reference voltage V_ref; the output terminal of the amplifier AP is connected to the analog-to-digital converter AD to provide the amplified electrical signal to the analog-to-digital converter AD (for example, the analog-to-digital converter AD chip), so that the analog-to-digital converter AD can collect data of the electrical signal output by the control unit 120.

[0196] For example, when the first pixel unit circuit 134 is also electrically connected to the amplifier AP and the analog-to-digital converter AD, the analog-to-digital converter AD corresponding to the first pixel unit circuit 134 can also collect data of the electrical signal output by the recognition unit 110 .

[0197] Fig.16 FIG. 1 is a schematic diagram of an ultrasonic sensor 100 provided by at least one embodiment of the present disclosure. Fig.16 As shown, the ultrasonic sensor 100 includes a texture recognition area 101 and a control area 102 (including a sub-control area) arranged in parallel in a first direction D1; the texture recognition area 101 includes 16 columns of recognition units 110 and first pixel unit circuits 134 corresponding to the recognition units 110 respectively; the texture recognition area 101 includes 4 columns of control units 120 and second pixel unit circuits 135 corresponding to the control units 120 respectively; in this case, when making Fig.16In the process of the ultrasonic sensor 100 shown, a high voltage may be directly applied to at least one of the first sub-electrode 112 and the second sub-electrode 113 to polarize the first portion 146. For specific methods, please refer to the relevant embodiments and will not be described in detail here. For example, the specific description of the first pixel unit circuit 134 and the second pixel unit circuit 135 can be referred to the aforementioned example and will not be described in detail here.

[0198] Fig.17 FIG. 1 shows a schematic diagram of an ultrasonic sensor 100 provided by at least one embodiment of the present disclosure. Fig.17 The ultrasonic sensor 100 shown is Fig.16 The ultrasonic sensor 100 shown is similar except that Fig.17 The ultrasonic sensor 100 shown adopts Fig. 9 and Fig.11 The pixel unit circuit shown; correspondingly, in the production Fig.17 During the manufacturing process of the ultrasonic sensor 100, the control area 102 may be formed by shielding the second portion 147. For specific methods, please refer to the relevant embodiments and will not be described in detail herein.

[0199] For example, for Fig.16 and Fig.17 For example, the four columns of data in each row of the control area 102 data can be averaged and sorted by row to obtain 20 averages. Each column in the reflection echo receiving area is subtracted from the above 20 averages according to the row correspondence, and the obtained frame of data is used as the raw data for the next step of data processing.

[0200] For example, the RMS value is calculated by taking the root mean square value after subtracting the average value from 50 frames of data. Each frame of data contains 20 rows × 16 columns, a total of 320 data. The RMS calculation formula is as follows.

[0201]

[0202] Here, x n Indicates the nth frame data, x n The average value of the reflected echo receiving area (i.e., the texture identification area) minus the average value of the control area 102; Represents the average value of n frames of data. For example, the signal-to-noise ratio is equal to the echo signal divided by the RMS. The RMS noise reduction effect after improvement is shown in Table 1. As shown in Table 1, after improvement, the test system has obvious noise reduction effect, the RMS noise reduction effect reaches 35%, and the signal-to-noise ratio is improved by 35%.

[0203] Table 1 Noise RMS noise reduction effect

[0204] Original RMS value Improved RMS Noise reduction effect Signal-to-noise ratio improvement effect 39 25 35％ 35％

[0205] It should be noted that Figure 8 and Fig.12 The corresponding relationship between the first sub-electrode, the second sub-electrode, the third sub-electrode and the fourth sub-electrode and the corresponding pads is schematically shown using wiring, but the specific connection method between the first sub-electrode, the second sub-electrode, the third sub-electrode and the fourth sub-electrode and the corresponding pads is not limited to Figure 8 and Fig.12 The example shown; according to actual application requirements, the electrical connection between the first sub-electrode, the second sub-electrode, the third sub-electrode and the fourth sub-electrode and the corresponding pads can be achieved through any combination of vias and routings, which will not be repeated here.

[0206] At least one embodiment of the present disclosure further provides a method for preparing an ultrasonic sensor 100, wherein the ultrasonic sensor 100 includes a texture recognition area 101 and a control area 102, wherein the control area 102 is located on at least one side of the texture recognition area 101, wherein the texture recognition area 101 includes at least one recognition unit 110, wherein the control area 102 includes at least one control unit 120, wherein at least one fingerprint recognition unit 110 includes a first dielectric material layer 111, and at least one control unit 120 includes a second dielectric material layer 121. The method includes: using the same material to form a first portion 146 for the first dielectric material layer 111 and a second portion 147 for the second dielectric material layer 121; performing a polarization treatment on at least the first portion 146 so that the first portion 146 is converted into a first dielectric material layer 111 having piezoelectric characteristics, and the second portion 147 is formed as a second electrode layer. The piezoelectric strain constant of the first dielectric material layer 111 is greater than the piezoelectric strain constant of the second dielectric material layer 121.

[0207] Fig.18 is an exemplary flow chart of a method for preparing an ultrasonic sensor 100 provided by at least one embodiment of the present disclosure. Fig.18 As shown, the method for preparing the ultrasonic sensor 100 includes the following steps S110 and S120.

[0208] Step S110 : forming a first portion 146 for the first dielectric material layer 111 and a second portion 147 for the second dielectric material layer 121 using the same material.

[0209] Step S120: performing polarization processing on at least the first portion 146, so that the first portion 146 is converted into a first dielectric material layer 111 having piezoelectric characteristics, and the second portion 147 is formed into a second electrode layer.

[0210] For example, the piezoelectric strain constant of the first dielectric material layer 111 is greater than the piezoelectric strain constant of the second dielectric material layer 121. For example, by making the piezoelectric strain constant of the first dielectric material layer 111 greater than the piezoelectric strain constant of the second dielectric material layer 121, the electrical signal output by the control unit 120 can be used as at least part of the noise in the electrical signal output by the identification unit 110 and deducted to obtain the electrical signal deducted from at least part of the noise and reduce the noise in the electrical signal output by the identification unit 110. For example, the electrical signal deducted from at least part of the noise can be used for raw data or pre-processed data for subsequent processing (for example, converting the electrical signal into a fingerprint image). For example, since the noise in the electrical signal deducted from at least part of the noise is reduced, it is possible to improve the quality of the image (for example, fingerprint image) obtained based on the electrical signal deducted from at least part of the noise.

[0211] In one example, the second dielectric material layer 121 may not have piezoelectric properties (e.g., piezoelectric effect); in this case, after the electrical signal output by the control unit 120 is taken as at least part of the noise in the electrical signal output by the identification unit 110 and subtracted, the useful signal (e.g., a useful signal that can be used to characterize the valley-ridge distribution) in the acquired electrical signal after at least part of the noise has been subtracted is not reduced, thereby improving the quality of the image (e.g., fingerprint image) acquired based on the electrical signal after at least part of the noise has been subtracted.

[0212] For example, by using the same material to form the first part 146 for the first dielectric material layer 111 and the second part 147 for the second dielectric material layer 121, the noise in the electrical signal output by the identification unit 110 including the first dielectric material layer 111 can be made closer to the noise in the electrical signal output by the control unit 120 including the second dielectric material layer 121, thereby further improving the quality of the image (for example, a fingerprint image) obtained based on the above-mentioned electrical signal with at least part of the noise deducted.

[0213] In the first example, polarizing at least the first portion 146 includes: while polarizing the first portion 146 using a polarization device, shielding the second portion 147 so that the polarization degree of the second portion 147 is less than that of the first portion 146 .

[0214] In the second example, polarizing at least the first portion 146 includes: applying a first voltage to the first sub-electrode 112, and applying a second voltage to the second sub-electrode 113. The voltage difference between the first voltage and the second voltage is greater than 1000V (eg, 3000V).

[0215] For the sake of clarity, the specific method of performing polarization treatment on at least the first portion 146 will be described after describing other steps that may be included in the method for preparing the ultrasonic sensor 100 , and will not be repeated here.

[0216] For example, the method for manufacturing the ultrasonic sensor 100 further includes the following steps S130 , S140 , and S150 .

[0217] Step S130: providing a back plate 130 .

[0218] Step S140: forming a first electrode layer.

[0219] Step S150: forming a second electrode layer.

[0220] For example, step S110-step S150 can be performed in the order of step S130, step S140, step S110, step S150 and step S120; correspondingly, the backplane 130, the first electrode layer, the layer where the first dielectric material layer 111 and the second dielectric material layer 121 are located, and the second electrode layer are arranged sequentially in a direction perpendicular to the backplane 130.

[0221] For example, by executing step S120 after step S150, the second electrode layer can be used to polarize at least the first portion 146, thereby simplifying the steps of the polarization process and reducing the difficulty of the polarization process.

[0222] For example, in step S130 , providing the back panel 130 includes the following steps S131 and S132 .

[0223] Step S131: providing a base substrate 131 .

[0224] Step S132 : forming a circuit structure 132 on the base substrate 131 .

[0225] For example, in step S131 , the base substrate 131 may be a glass substrate, a quartz substrate, a semiconductor substrate (eg, a silicon substrate), a plastic substrate (eg, a polyethylene terephthalate (PET) substrate, a polyimide substrate) or a substrate made of other suitable materials.

[0226] For example, in step S132, forming the circuit structure 132 on the substrate includes: directly forming the circuit structure 132 on the base substrate 131, or first forming the circuit structure 132 and then transferring the circuit structure 132 to the base substrate 131. For example, the circuit structure 132 included in the backplane 130 can be manufactured by a CMOS process.

[0227] For example, in step S132, the circuit structure 132 includes a plurality of pixel unit circuits. For example, a first portion of the plurality of pixel unit circuits is configured to be electrically connected to at least one recognition unit 110 to apply a voltage to at least one recognition unit 110 and cause the recognition unit 110 to emit an ultrasonic wave, and to obtain an electrical signal (e.g., a current signal) from at least one recognition unit 110. For example, a second portion of the plurality of pixel unit circuits is configured to be electrically connected to at least one control unit 120 to apply a voltage to at least one control unit 120, and to obtain an electrical signal (e.g., a current signal) from at least one control unit 120. For example, the circuit structure 132 includes at least one of a wiring, a via, and a pad for electrical connection. For example, the specific structure of the pixel unit circuit is referred to the aforementioned ultrasonic sensor 100, which will not be repeated here.

[0228] For example, the first electrode layer includes a first sub-electrode 112 of at least one fingerprint recognition unit 110 and a third sub-electrode 122 of at least one control unit 120. For example, the first sub-electrode 112 and the third sub-electrode 122 may be referred to as receiving sub-electrodes, and the second sub-electrode 113 and the fourth sub-electrode 123 may be referred to as driving sub-electrodes (or transmitting sub-electrodes).

[0229] For example, in step S140 , forming the first electrode layer includes the following steps S141 and S142 .

[0230] Step S141 : forming a first electrode material layer on the side of the back plate 130 where the circuit structure 132 is formed.

[0231] Step S142 : patterning the first electrode material layer to form a first sub-electrode 112 and a third sub-electrode 122 .

[0232] For example, by forming a first electrode material layer on the side of the back plate 130 where the circuit structure 132 is formed, the first sub-electrode 112 and the third sub-electrode 122 formed subsequently can be more easily electrically connected to the circuit structure 132 .

[0233] For example, the first electrode material layer may be formed by using a transparent conductive material or other applicable materials, such as indium tin oxide (ITO) or indium zinc oxide (IZO).

[0234] For example, the method of patterning the first electrode material layer may refer to the relevant technology, and the specific structure of the first electrode material layer may refer to the aforementioned embodiment of the ultrasonic sensor 100, which will not be described in detail here.

[0235] For example, in step S110 , forming the first portion 146 for the first dielectric material layer 111 and the second portion 147 for the second dielectric material layer 121 using the same material includes the following steps S111 and S112 .

[0236] Step S111: forming a dielectric material layer on the first electrode layer using the same material.

[0237] Step S112 : patterning the dielectric material layer to form a first portion 146 for the first dielectric material layer 111 and a second portion 147 for the second dielectric material layer 121 .

[0238] For example, the same material may be polyvinylidene fluoride (PVDF), in which case at least one of casting, melting, electrospinning and spin coating may be used to form a dielectric material layer on the first electrode layer. For example, the thickness of PVDF may be 9 microns.

[0239] It should be noted that the same material is not limited to polyvinylidene fluoride. For example, the same material may also be a material such as zinc oxide (ZnO) that does not have piezoelectric properties before polarization but has piezoelectric properties after polarization. For example, the dielectric material layer is formed on the side of the first electrode layer away from the back plate 130.

[0240] For example, the dielectric material layer may be patterned such that an orthographic projection of the first portion 146 on the backplane is spaced apart from an orthographic projection of the second portion 147 on the backplane.

[0241] In some examples, the dielectric material layer may not be patterned, but the portion of the dielectric material layer corresponding to the texture recognition area may be directly polarized.

[0242] For example, the method of patterning the dielectric material layer can refer to the relevant technology, and the specific structure of the dielectric material layer corresponds to the structure of the first dielectric material layer 111 and the second dielectric material layer 121 (for example, shape, size and arrangement), and can refer to the aforementioned embodiment of the ultrasonic sensor 100, which will not be repeated here.

[0243] For example, in step S150 , forming the second electrode layer includes the following steps S151 and S152 .

[0244] Step S151: forming a second electrode material layer on the dielectric material layer.

[0245] Step S152 : patterning the second electrode material layer to form a second sub-electrode 113 and a fourth sub-electrode 123 .

[0246] For example, the second sub-electrode 113 overlaps with the first sub-electrode 112 and the first portion 146 to form the identification unit 110 , and the fourth sub-electrode 123 overlaps with the second sub-electrode 113 and the second portion 147 to form the control unit 120 .

[0247] For example, the second electrode material layer may be formed by using a transparent conductive material or other applicable materials, such as indium tin oxide (ITO) or indium zinc oxide (IZO).

[0248] For example, at least one of the first electrode material layer and the second electrode material layer may be made of a conjugated microporous polymer electrode material (TAT). For example, the second electrode material layer may be made of a conjugated microporous polymer electrode material (TAT).

[0249] For example, the method of patterning the second electrode material layer may refer to the relevant technology, and the specific structure of the second electrode material layer may refer to the aforementioned embodiment of the ultrasonic sensor 100, which will not be described in detail here.

[0250] For example, the method for manufacturing the ultrasonic sensor 100 further includes at least one of the following steps S160 , S170 , and S180 .

[0251] Step S160: forming a first insulating layer 191 on the back plate 130 having the first electrode layer formed thereon (see Fig.19A ).

[0252] Step S170: forming a second insulating layer 192 on a side of the second electrode layer away from the dielectric material layer (see Fig.19A ).

[0253] Step S180 : forming a metal film 195 on a side of the second insulating layer 192 away from the second electrode layer.

[0254] For example, step S160 may be performed after step S140 and before step S110. For example, step S170 may be performed after step S150 and before step S120. For example, step S180 may be performed after step S120.

[0255] For example, the first insulating layer 191 and the second insulating layer 192 can be made of inorganic materials such as silicon oxide (SiOx), silicon oxynitride (SiNxOy), silicon nitride (SiNx), organic materials, or other suitable materials. For example, the first insulating layer 191 can flatten the side of the first electrode layer away from the back plate 130, and the second insulating layer 192 can flatten the side of the second electrode layer away from the back plate 130, which can be beneficial to subsequent processes. For example, the first insulating layer 191 and the second insulating layer 192 can be made of SU 8 photoresist. For example, the thickness of at least one of the first insulating layer 191 and the second insulating layer 192 is 20 microns. For example, the first insulating layer 191 can also be called a primer C.

[0256] For example, in step S180, the metal film 195 may be a silver film; in this case, forming the metal film 195 on the side of the second insulating layer 192 away from the second electrode layer includes: screen printing a layer of silver paste on the side of the second insulating layer 192 away from the second electrode layer; converting the silver paste into a silver film. For example, by forming a metal film 195 (e.g., a silver film) on the side of the second insulating layer 192 away from the second electrode layer, the frequency of the ultrasonic wave emitted by the identification unit 110 can be adjusted. For example, the metal film 195 (e.g., a silver film) can be used as an acoustic matching layer and used to reflect ultrasonic waves. For example, the thickness of the silver film can be 18 microns. For example, the metal film 195 (e.g., a silver film) can be the outermost film layer of the ultrasonic sensor 100.

[0257] In the first example, in step S120, at least the first portion 146 is polarized to convert the first portion 146 into a first dielectric material layer 111 having piezoelectric properties and the second portion 147 is formed into a second electrode layer, including the following steps S151 to S153.

[0258] Step S151: placing a stack of a first electrode layer, a dielectric material layer and a second electrode layer in a polarization device.

[0259] Step S152 : enabling the polarization device to form plasma to perform polarization treatment on the first portion 146 .

[0260] Step S153: applying a shielding voltage to the fourth sub-electrode 123 to shield the plasma.

[0261] For example, in step S151, the stacked structure of the back plate 130, the first electrode layer, the dielectric material layer and the second electrode layer may be placed on the Figure 5 In the polarization device shown.

[0262] Fig.19Ais an exemplary cross-sectional view of a stacked structure of a back plate 130 , a first electrode layer, a dielectric material layer, and a second electrode layer provided by at least one embodiment of the present disclosure.

[0263] For example, in step S152, causing the polarization device to form plasma includes causing Figure 5 A high voltage electric field is formed between the discharge electrode 302 and the grid electrode 303 of the polarization device shown, whereby the discharge electrode can ionize the air in the surrounding environment of the discharge electrode and generate plasma.

[0264] For example, in step S153, applying the shielding voltage to the fourth sub-electrode 123 includes applying the shielding voltage (eg, ground voltage) to the fourth sub-electrode 123 via a polarization device. For example, the fourth sub-electrode 123 may be connected to the ground terminal of the polarization device via the back plate 130.

[0265] For example, Fig.19A As shown, the upper surface of the second insulating layer 192 (e.g., SiNx) is in contact with the electron cloud in the polarization device, so the second sub-electrode 113 (e.g., Tx end) is at a high potential, and the first sub-electrode 112 is connected to the ground end of the polarization device via the back plate 130, so an electric potential difference is generated between the upper and lower ends of the PVDF, resulting in polarization.

[0266] For example, applying the shielding voltage on the fourth sub-electrode 123 includes: applying the shielding voltage on the fourth sub-electrode 123 using the first trace 141. For example, a terminal for applying the shielding voltage (for example, a ground terminal of a polarization device) is electrically connected to the first pad 151, so that the shielding voltage provided by the terminal for applying the shielding voltage can be applied to the fourth sub-electrode 123 electrically connected to the first trace 141 via the first pad 151 and the first trace 141. For example, in at least one example of the method for manufacturing the ultrasonic sensor 100, the shielding voltage is 10V-30V (for example, 15V, 20V, or 25V).

[0267] For example, a shielding voltage may be applied to the fourth sub-electrode 123 before or simultaneously with the polarization device forming plasma, that is, step S153 may be performed before or simultaneously with step S152.

[0268] Fig.19B It is an exemplary diagram of a first example of a polarization processing method provided by at least one embodiment of the present disclosure.

[0269] For example, Fig.19BAs shown, for the first example, when at least the first part 146 is polarized, a voltage V_in_AA can be applied to the first sub-electrode 112 located in the texture identification area 101, and a voltage V_in_dm and a shielding voltage In_3_dm can be applied to the third sub-electrode 122 and the fourth sub-electrode 123 of the control area 102, respectively, and the second sub-electrode 113 located in the texture identification area 101 is suspended.

[0270] For example, for the first example, a voltage V_in_AA may be applied to the first sub-electrode 112 via the first voltage input terminal V_in of the pixel unit circuit electrically connected to the first sub-electrode 112, and the voltage V_in_AA is, for example, a ground voltage. For example, a voltage V_in_dm may be applied to the third sub-electrode 122 via the first voltage input terminal V_in of the pixel unit circuit electrically connected to the third sub-electrode 122, and the voltage V_in_dm is, for example, a ground voltage. For example, a voltage shielding voltage In_3_dm may be applied to the fourth sub-electrode 123 via the first terminal In_1 of the control unit 120, and the voltage shielding voltage In_3_dm is, for example, a ground voltage.

[0271] In the second example, in step S120, at least the first part 146 is polarized so that the first part 146 is converted into a first dielectric material layer 111 with piezoelectric properties, and the second part 147 is formed into a second electrode layer, including: applying a first voltage to the first sub-electrode 112, and applying a second voltage to the second sub-electrode 113.

[0272] For example, the voltage difference between the first voltage and the second voltage is greater than 1000V (for example, 3000V). For example, the first voltage may be a ground voltage; the second voltage may be a negative high voltage. For example, the first voltage and the second voltage may be equal to 0V and negative 3KV, respectively.

[0273] Fig. 20 is an exemplary diagram of a second example of a polarization processing method provided by at least one embodiment of the present disclosure.

[0274] For example, Fig. 20 As shown, for the second example, when at least the first part 146 is polarized, a voltage V_in_AA can be applied to the first sub-electrode 112 located in the texture identification area 101, a voltage In_1_AA can be applied to the second sub-electrode 113 located in the texture identification area 101, and the third sub-electrode 122 and the fourth sub-electrode 123 of the control area 102 are suspended.

[0275] For example, for the second example, a voltage V_in_AA can be applied to the first sub-electrode 112 via the first voltage input terminal V_in of the pixel unit circuit electrically connected to the first sub-electrode 112, and the voltage V_in_AA is, for example, a ground voltage; a voltage In_1_AA is applied to the second sub-electrode 113 via the first terminal In_1 of the identification unit 110, and the voltage In_1_AA is, for example, a negative high voltage (for example, negative 3 kilovolts).

[0276] Fig.21 is another example diagram of a second example of the polarization processing method provided by at least one embodiment of the present disclosure.

[0277] For example, Fig.21 As shown, in the second example, after all the film layers of the ultrasonic sensor 100 are manufactured, a first voltage (e.g., a ground voltage) can be applied to the first sub-electrode 112 via the back plate 130, and a second voltage (e.g., a negative high voltage) can be applied to the second electrode, thereby making the first unidirectional conduction circuit 181 (e.g., a diode) of the pixel unit circuit conductive, the first portion 146 is located in the high-voltage electric field, the first portion 146 is polarized under the action of the high-voltage electric field, and the first portion 146 is converted into a first dielectric material layer 111 having piezoelectric properties, and the second portion 147 is formed as a second electrode layer.

[0278] For example, Fig.21 As shown, the ultrasonic sensor 100 may include a first insulating layer 191, a second insulating layer 192 ( Fig.21 ) and a third insulating layer 193. For example, the third insulating layer 193 may be made of SU 8 photoresist and have a thickness of 20 micrometers.

[0279] Fig. 22 is a schematic diagram of monitoring the quality of polarization-related parameters provided by at least one embodiment of the present disclosure. Fig. 22 As shown, when or after the first portion 146 is subjected to the polarization treatment, the quality of the parameters related to the polarization can be monitored, thereby making the polarization degree and the piezoelectric strain constant D33 of the first dielectric material layer 111 closer to the designed value.

[0280] It should be noted that the second example is not limited to polarizing at least the first portion 146 after all the film layers of the ultrasonic sensor 100 are manufactured. According to actual application requirements, the first portion 146 can be polarized after the second electrode layer of the ultrasonic sensor 100 is formed, which is not repeated here.

[0281] It should be noted that, for the sake of clarity, Fig.21 Only the control area is shown, and the second insulating layer 192 is not shown.

[0282] For example, for the first example and the second example of the preparation method provided by at least one embodiment of the present disclosure, after at least the first portion 146 is polarized, the Figure 6 The cutting line 161 shown cuts the back plate 130 to remove the pad for applying the shielding voltage or the pad for applying the first voltage and the second voltage. However, at least one embodiment of the present disclosure is not limited thereto, and in some examples, the pad for applying the shielding voltage or the pad for applying the first voltage and the second voltage may also be retained in the final product of the ultrasonic sensor 100.

[0283] Some embodiments of the present disclosure further provide a display device, Fig.23 An exemplary block diagram of a display device provided for at least one embodiment of the present disclosure, Fig.24 An exemplary structural diagram of a display device provided for at least one embodiment of the present disclosure. Fig.23 and Fig.24 As shown, the display device provided by the embodiment of the present disclosure includes: a display panel 200 and an ultrasonic sensor 100. The display panel 200 and the ultrasonic sensor 100 are stacked in a direction perpendicular to the display device.

[0284] In some examples, the row direction of the ultrasonic sensor 100 corresponds to the extension direction of the gate lines of the display panel 200. In other examples, the row direction of the ultrasonic sensor 100 corresponds to the extension direction of the data lines of the display panel 200.

[0285] For example, the ultrasonic sensor 100 is located on one side of the display panel 200. For example, one side of the display panel may refer to the display side of the display panel (e.g., the light-emitting side) or the side opposite to the display side of the display panel (e.g., the non-light-emitting side or the side opposite to the light-emitting side). Fig.24 As shown, the display panel 200 is located on a side of the second sub-electrode 113 away from the first sub-electrode 112 .

[0286] For example, the display panel may include: an organic light-emitting diode (OLED) display panel, a quantum dot display panel or a liquid crystal display (LCD) display panel. Fig.24 The description is given by taking an OLED display panel or a quantum dot display panel as an example.

[0287] When the display panel is an OLED display panel or a quantum dot display panel, since the OLED display panel or the quantum dot display panel is a self-luminous device, the ultrasonic sensor 100 can be arranged on a side opposite to the display side of the OLED display panel.

[0288] For example, the OLED display panel includes: an OLED array substrate 202 and a cover plate 201, the OLED array substrate 202 includes a plurality of pixel units, each pixel unit includes an OLED light-emitting device and a pixel circuit for driving the OLED light-emitting device; the OLED light-emitting device includes: an anode, a cathode and an organic light-emitting layer arranged between the cathode and the anode, and packaging glue is arranged between the OLED array substrate 202 and the cover plate 201 to seal the OLED light-emitting device on the OLED array substrate in a closed environment.

[0289] For example, the cover plate 201 is a flexible cover plate, which can realize the flexible foldability of the display panel. For example, the display device further includes: optical glue (not shown in the figure), which is used to connect the display panel 200 and the ultrasonic sensor 100.

[0290] For example, the area of ​​the ultrasonic sensor 100 is equal to the area of ​​the display area of ​​the display panel 200. For example, by making the area of ​​the ultrasonic sensor 100 equal to the area of ​​the display area of ​​the display panel 200, full-screen fingerprint recognition can be achieved. For example, when the display panel 200 also includes a peripheral area surrounding the display area, the area of ​​the ultrasonic sensor 100 can also be greater than the area of ​​the display area of ​​the display panel 200. For example, the area of ​​the ultrasonic sensor 100 refers to the area of ​​the surface of the ultrasonic sensor 100 parallel to the display surface of the display device; the area of ​​the display panel 200 refers to the area of ​​the surface of the display panel 200 parallel to the display surface of the display device.

[0291] Although the disclosure has been described in detail above with general descriptions and specific implementation methods, it is obvious to those skilled in the art that some modifications or improvements may be made to the embodiments of the disclosure. Therefore, these modifications or improvements made without departing from the spirit of the disclosure are within the scope of protection claimed by the disclosure.

[0292] The above description is merely an exemplary embodiment of the present disclosure and is not intended to limit the protection scope of the present disclosure. The protection scope of the present disclosure is determined by the appended claims.

Claims

1. An ultrasonic sensor, comprising a pattern recognition area and a control area, in, The control area is located on at least one side of the texture recognition area; The texture recognition area includes at least one recognition unit, and the control area includes at least one control unit; The at least one identification unit comprises a first layer of dielectric material; The at least one control unit includes a second dielectric material layer; The first dielectric material layer and the second dielectric material layer are made of the same material; The first dielectric material layer has piezoelectric properties; and The piezoelectric strain constant of the first dielectric material layer is greater than the piezoelectric strain constant of the second dielectric material layer.

2. The ultrasonic sensor according to claim 1, wherein: A ratio of a piezoelectric strain constant of the first dielectric material layer to a piezoelectric strain constant of the second dielectric material layer is greater than or equal to 2.

3. The ultrasonic sensor according to claim 1, wherein: The first dielectric material layer and the second dielectric material layer both include polyvinylidene fluoride films, and the polyvinylidene fluoride films included in the first dielectric material layer and the polyvinylidene fluoride films included in the second dielectric material layer have different polarization degrees.

4. The ultrasonic sensor according to any one of claims 1 to 3, further comprising a back plate, in, An orthographic projection of the second dielectric material layer on the backplane is spaced apart from an orthographic projection of the first dielectric material layer on the backplane.

5. The ultrasonic sensor according to any one of claims 1 to 3, wherein: The control area includes a first sub-control area and a second sub-control area; and The first sub-control area and the second sub-control area are located at two sides of the pattern recognition area in the first direction.

6. The ultrasonic sensor according to any one of claims 1 to 3, wherein: The at least one identification unit further comprises a first sub-electrode and a second sub-electrode; The first dielectric material layer is sandwiched between the first sub-electrode and the second sub-electrode in a direction perpendicular to the ultrasonic sensor; The at least one comparison unit further includes a third sub-electrode and a fourth sub-electrode; and The second dielectric material layer is sandwiched between the third sub-electrode and the fourth sub-electrode in a direction perpendicular to the ultrasonic sensor.

7. The ultrasonic sensor according to claim 6, wherein: The first sub-electrode and the third sub-electrode are located in the first electrode layer; The second sub-electrode and the fourth sub-electrode are located in the second electrode layer; The first sub-electrode and the third sub-electrode have the same shape and size; and The second sub-electrode and the fourth sub-electrode have the same shape and size.

8. The ultrasonic sensor according to claim 6, further comprising a back plate, a first trace and a second trace, in, The first wiring and the second wiring are both electrically connected to the fourth sub-electrode; The first wiring extends from a position electrically connected to the fourth sub-electrode to an edge of the back plate; The orthographic projection of the end of the second wiring on the backplane is spaced apart from the edge of the backplane.

9. The ultrasonic sensor according to claim 8, further comprising a third wiring, a fourth wiring, a fifth wiring and a sixth wiring, in, The third wiring is electrically connected to the first sub-electrode, and the fourth wiring is electrically connected to the third sub-electrode; The fifth wiring is electrically connected to the first sub-electrode, and the sixth wiring is electrically connected to the third sub-electrode; The third wiring extends from a position electrically connected to the first sub-electrode to an edge of the back plate; and The fourth wiring extends from a position electrically connected to the third sub-electrode to an edge of the back plate.

10. The ultrasonic sensor according to claim 6, further comprising a back plate, a seventh trace and an eighth trace, in, The seventh wiring is electrically connected to the first sub-electrode, and the eighth wiring is electrically connected to the first sub-electrode; The seventh wiring extends from a position electrically connected to the first sub-electrode to an edge of the back plate; and The orthographic projection of the end of the eighth wiring on the backplane is spaced apart from the edge of the backplane.

11. The ultrasonic sensor according to claim 10, wherein: The backplane includes at least one first pixel unit circuit and at least one second pixel unit circuit; The at least one first pixel unit circuit is electrically connected to the first sub-electrode of the at least one identification unit respectively; The at least one second pixel unit circuit is electrically connected to the third sub-electrode of the at least one control unit respectively; Each of the at least one first pixel unit circuit and the at least one second pixel unit circuit comprises a first voltage input terminal, a voltage output terminal, a driving transistor and a first unidirectional conduction circuit; The first unidirectional conducting circuit comprises a first end and a second end, and the conducting direction of the first unidirectional conducting circuit is from the first end of the first unidirectional conducting circuit to the second end of the first unidirectional conducting circuit; The control end of the driving transistor and the second end of the first unidirectional conducting circuit are both electrically connected to the voltage output end; The first end of the first unidirectional conductive circuit and the first voltage input end are both electrically connected to the first node; The voltage output terminal of the at least one first pixel unit circuit is electrically connected to the first sub-electrode; The driving transistor of the at least one first pixel unit circuit is configured to be electrically connected to the first power supply terminal and to convert the voltage signal on the first sub-electrode into a current signal; The voltage output terminal of the at least one second pixel unit circuit is electrically connected to the third sub-electrode; The at least one first pixel unit circuit further comprises a second voltage input terminal, and the second voltage input terminal of the at least one first pixel unit circuit is electrically connected to the first node; The seventh wiring is electrically connected to the second voltage input terminal of the at least one first pixel unit circuit; as well as The eighth wiring is electrically connected to the first voltage input terminal of the at least one first pixel unit circuit.

12. The ultrasonic sensor according to claim 11, further comprising a second unidirectional conduction circuit and a third unidirectional conduction circuit, in, The second unidirectional conducting circuit comprises a third end and a fourth end, and a conducting direction of the second unidirectional conducting circuit is from the third end of the second unidirectional conducting circuit to the fourth end of the second unidirectional conducting circuit; The third unidirectional conducting circuit comprises a fifth end and a sixth end, and a conducting direction of the third unidirectional conducting circuit is from the fifth end of the third unidirectional conducting circuit to the sixth end of the third unidirectional conducting circuit; The third terminal of the second unidirectional conducting circuit is connected to the first node, and the fourth terminal of the second unidirectional conducting circuit is connected to the second power supply terminal; The fifth end of the third unidirectional conducting circuit is connected to the third power supply end, and the sixth end of the third unidirectional conducting circuit is connected to the first node; as well as The second voltage input terminal of the at least one first pixel unit circuit is connected to the fifth terminal of the third unidirectional conducting circuit.

13. A display device, comprising a display panel and the ultrasonic sensor according to any one of claims 1 to 12; the display panel and the ultrasonic sensor are stacked in a direction perpendicular to the display device.

14. The display device according to claim 13, wherein: The ultrasonic sensor is located on the non-light-emitting side of the display panel, and the display panel is an organic light-emitting diode display panel or a quantum dot display panel.

15. A method for preparing an ultrasonic sensor, wherein: The ultrasonic sensor comprises a texture recognition area and a control area, wherein the control area is located at least on one side of the texture recognition area, the texture recognition area comprises at least one recognition unit, the control area comprises at least one control unit, the at least one recognition unit comprises a first dielectric material layer, and the at least one control unit comprises a second dielectric material layer; The method comprises: forming a first portion for the first dielectric material layer and a second portion for the second dielectric material layer using the same material; performing a polarization process on at least the first portion so that the first portion is converted into the first dielectric material layer having piezoelectric properties, and the second portion is formed into the second dielectric material layer, Wherein, the piezoelectric strain constant of the first dielectric material layer is greater than the piezoelectric strain constant of the second dielectric material layer.

16. The method for preparing an ultrasonic sensor according to claim 15, wherein: The at least performing polarization processing on the first portion comprises: The second part is shielded while the first part is polarized using a polarization device, so that the polarization degree of the second part is smaller than that of the first part.

17. The method for preparing an ultrasonic sensor according to claim 15, further comprising: forming a first electrode layer and a second electrode layer, wherein the first electrode layer includes a first sub-electrode of the at least one identification unit and a third sub-electrode of the at least one control unit, and the second electrode layer includes a second sub-electrode of the at least one identification unit and a fourth sub-electrode of the at least one control unit; and The forming of the first portion for the first dielectric material layer and the second portion for the second dielectric material layer using the same material comprises: forming a dielectric material layer on the first electrode layer using the same material; The dielectric material layer is located between the first electrode layer and the second electrode layer, and includes the first portion and the second portion.

18. The method for preparing an ultrasonic sensor according to claim 17, wherein: The at least performing polarization processing on the first portion comprises: placing a stack of the first electrode layer, the dielectric material layer and the second electrode layer in a polarization device; enabling the polarization device to form plasma to perform the polarization treatment on the first portion; and A shielding voltage is applied to the fourth sub-electrode to shield the plasma.

19. The method for preparing an ultrasonic sensor according to claim 18, wherein: Before or while the polarization device is caused to form the plasma, the shielding voltage is applied to the fourth sub-electrode.

20. The method for preparing an ultrasonic sensor according to claim 18, wherein: The ultrasonic sensor further includes a back plate, a first wiring and a second wiring, wherein the first wiring and the second wiring are both electrically connected to the fourth sub-electrode; the first wiring extends from a position electrically connected to the fourth sub-electrode to an edge of the back plate; The orthographic projection of the end of the second wiring on the backplane is spaced apart from the edge of the backplane; as well as The applying the shielding voltage on the fourth sub-electrode comprises: The shielding voltage is applied to the fourth sub-electrode using the first wiring.

21. The method for preparing an ultrasonic sensor according to any one of claims 18 to 20, wherein: The shielding voltage is 10V-30V.

22. The method for preparing an ultrasonic sensor according to claim 17, wherein: The at least performing polarization processing on the first portion comprises: applying a first voltage to the first sub-electrode, applying a second voltage to the second sub-electrode, Wherein, a voltage difference between the first voltage and the second voltage is greater than 1000V.

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