Fingerprint identification module and method, electronic device, control device and storage medium

Abstract

A fingerprint identification module and method, an electronic device, a control device, and a storage medium. The fingerprint identification module comprises a pixel circuit layer, a first electrode layer, a first piezoelectric thin film layer, a second electrode layer, a second piezoelectric thin film layer and a third electrode layer which are arranged in sequence, wherein the first piezoelectric thin film layer is electrically connected to the pixel circuit layer by means of the first electrode layer, and the polarization directions of the first piezoelectric thin film layer and the second piezoelectric thin film layer are the same. In a transmission state, a voltage is applied between the second electrode layer and the third electrode layer, so that the first piezoelectric thin film layer generates an ultrasonic signal, and the first electrode layer and the second electrode layer are disconnected. The fingerprint identification module can avoid the voltage division effect of the pixel circuit layer, the sound pressure sensitivity of the fingerprint identification module is improved, and energy consumption is reduced.

Description

Fingerprint recognition modules and methods, electronic devices, control devices and storage media

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411222161.5, filed on August 30, 2024, entitled "Fingerprint Recognition Module and Method, Electronic Device, Control Device and Storage Medium", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of fingerprint recognition, specifically to a fingerprint recognition module and method, electronic device, control device, and storage medium. Background Technology

[0004] Fingerprint information, due to its uniqueness, difficulty in acquisition, and ease of use, has become one of the mainstream identity recognition technologies in consumer electronics, smart homes, and the defense industry. Currently, the main fingerprint recognition technologies include capacitive, optical, and ultrasonic. Among them, ultrasonic fingerprint recognition, with its advantages of not relying on screen transmittance, fast unlocking speed, wet and underwater fingerprint unlocking, and 3D anti-counterfeiting features, is gradually becoming a new choice for major mobile phone terminals. Ultrasonic fingerprint recognition modules mainly work by applying voltage to a piezoelectric layer to send ultrasonic signals to the fingerprint. The ultrasonic signals reflected back from the fingerprint act on the piezoelectric layer, causing it to generate electrical signals. The pixel circuit layer then captures these electrical signals to form a fingerprint pattern. However, existing ultrasonic fingerprint recognition modules waste electrical energy and reduce the acoustic pressure sensitivity of the ultrasonic waves during transmission. Summary of the Invention

[0005] This application provides a fingerprint recognition module and method, electronic device, control device and storage medium to reduce the voltage division effect of the pixel circuit layer, improve the acoustic pressure sensitivity of the fingerprint recognition module and reduce power consumption.

[0006] In a first aspect, this application provides a fingerprint recognition module, which includes a pixel circuit layer, a first electrode layer, a first piezoelectric thin film layer, a second electrode layer, a second piezoelectric thin film layer, and a third electrode layer arranged sequentially. The first piezoelectric thin film layer is electrically connected to the pixel circuit layer through the first electrode layer. The polarization directions of the first piezoelectric thin film layer and the second piezoelectric thin film layer are the same. In the transmitting state of the fingerprint recognition module, a voltage is applied between the second electrode layer and the third electrode layer to make the first piezoelectric thin film layer generate an ultrasonic signal, and the first electrode layer and the second electrode layer are disconnected.

[0007] The fingerprint recognition module of this application includes two piezoelectric thin film layers, serving as a piezoelectric receiving layer and a piezoelectric emitting layer, respectively. The first piezoelectric thin film layer acts as the piezoelectric receiving layer, and the second piezoelectric thin film layer acts as the piezoelectric emitting layer. In the emitting state of the fingerprint recognition module, a voltage is directly applied to the electrode layers on both sides of the second piezoelectric thin film layer, i.e., the second electrode layer and the third electrode layer, causing the second piezoelectric thin film layer to vibrate and generate ultrasonic waves. In this state, the first electrode layer and the second electrode layer are disconnected, and no voltage is applied between them; therefore, the first piezoelectric thin film layer does not generate ultrasonic waves. During this process, the voltage is directly applied to both sides of the second piezoelectric thin film layer through the second electrode layer and the third electrode layer, avoiding additional parasitic resistance and voltage division caused by parasitic resistance, thus reducing the effective voltage applied to the second piezoelectric thin film layer. Therefore, the fingerprint recognition module of this application can reduce the energy consumption of the fingerprint recognition module in the emitting state and improve the acoustic pressure sensitivity. Furthermore, during the fabrication of the fingerprint recognition module, after forming the first and second piezoelectric thin film layers, the first and second piezoelectric thin film layers are polarized to give them piezoelectric properties. If the polarization directions of the first and second piezoelectric thin film layers are different, different polarization equipment is required for their polarization treatment, increasing costs. In this application, the polarization directions of the first and second piezoelectric thin film layers are the same, which can save polarization costs and improve polarization efficiency.

[0008] In one implementation, when the fingerprint recognition module is in the transmitting state, the second electrode layer is grounded, and the third electrode layer is coupled to the AC output terminal of the power supply module; or, the third electrode layer is grounded, and the second electrode layer is coupled to the AC output terminal of the power supply module. With these connection methods, an AC voltage can be applied to the second piezoelectric thin film layer to cause it to vibrate and generate an ultrasonic signal.

[0009] In one implementation, when the fingerprint recognition module is in the receiving state, the second and third electrode layers are disconnected. The first piezoelectric thin film layer receives the ultrasonic signal and generates an electrical signal. The pixel circuit layer is connected to the first electrode layer, acquires the electrical signal, and outputs it externally. In the receiving state of the fingerprint recognition module, only the first piezoelectric thin film layer is used as the piezoelectric receiving layer to receive the ultrasonic signal, avoiding crosstalk caused by too many piezoelectric thin film layers simultaneously receiving the ultrasonic signal.

[0010] In one implementation, the second electrode layer is grounded when the fingerprint recognition module is in the receiving state. Grounding the second electrode layer forms a conductive circuit between the pixel circuit layer and the second electrode layer, allowing the electrical signal generated by the first piezoelectric thin film layer to be transmitted to the pixel circuit layer. The pixel circuit layer acquires and processes this electrical signal to form a fingerprint image signal for output.

[0011] In one implementation, the thickness of the second electrode layer is ≤λ / 10, where λ is the wavelength of the ultrasonic wave. When the fingerprint recognition module is attached to the back, the ultrasonic signal will pass through the second electrode layer during transmission, or during the reception of the ultrasonic signal in the first piezoelectric film layer, the ultrasonic signal will penetrate the third electrode layer, the second piezoelectric film layer, and the second electrode layer to be transmitted to the first piezoelectric film layer. Reducing the thickness of the second electrode layer to λ / 10 can reduce the attenuation of the ultrasonic wave and improve the transmission and reception strength of the ultrasonic signal.

[0012] In one implementation, the acoustic impedance differences between the first, second, and third electrode layers and the first piezoelectric thin film layer are all ≤2MRaly; the acoustic impedance differences between the first, second, and third electrode layers and the second piezoelectric thin film layer are all ≤2MRaly. Controlling the acoustic impedance differences between each electrode layer and the first and second piezoelectric thin film layers within 2MRaly reduces ultrasonic signal reflection at various interfaces, thereby increasing signal reception strength.

[0013] In one implementation, the resistances of the first, second, and third electrode layers are all ≤1Ω. The second and third electrode layers have lower resistances to reduce voltage division during transmission, thereby reducing power consumption during transmission. The first electrode layer has lower resistance to reduce signal transmission losses.

[0014] Secondly, this application provides a fingerprint recognition module, which includes a pixel circuit layer, a piezoelectric receiving layer and a piezoelectric emitting layer arranged sequentially. The piezoelectric emitting layer includes at least two piezoelectric thin film layers with the same polarization direction. Each piezoelectric thin film layer has an electrode layer on both sides, and adjacent piezoelectric thin film layers share an electrode layer. The piezoelectric receiving layer and the pixel circuit layer are electrically connected through the electrode layer.

[0015] In the transmitting state of the fingerprint recognition module, a voltage is applied between the electrode layers on both sides of each piezoelectric thin film layer in the piezoelectric transmitting layer to generate an ultrasonic signal, and the electrode layers on both sides of the piezoelectric receiving layer are disconnected; wherein, the phase difference of the voltage applied between adjacent piezoelectric thin film layers in the piezoelectric transmitting layer meets a preset range value.

[0016] The fingerprint recognition module of this application includes two piezoelectric layers: a piezoelectric receiving layer and a piezoelectric emitting layer. The piezoelectric emitting layer comprises at least two piezoelectric thin film layers, all with the same polarization direction. Since the piezoelectric thin film layers in the emitting layer have the same polarization direction, adjacent piezoelectric thin film layers share a common electrode layer. Therefore, the phase difference of the voltage applied between adjacent piezoelectric thin film layers in the emitting layer must meet a preset range value to ensure that the vibration directions of adjacent piezoelectric thin film layers are consistent. In the emitting state of the fingerprint recognition module, a voltage is directly applied to both sides of each piezoelectric thin film layer in the emitting layer to cause each piezoelectric thin film layer to vibrate and generate ultrasonic signals. No voltage is applied to the two ends of the piezoelectric receiving layer, thereby avoiding the generation of additional parasitic resistance and capacitance that would cause voltage division. Therefore, the fingerprint recognition module of this application can reduce the energy consumption of the piezoelectric emitting layer and improve the acoustic pressure sensitivity.

[0017] In one implementation, the preset range is 180±45°. When the phase difference of the voltage between the electrode layers on both sides of each piezoelectric thin film layer in the piezoelectric emitting layer meets 180±45°, for example, 180±25°, the overall vibration amplitude of the piezoelectric emitting layer can be increased, thereby increasing the signal strength of the ultrasonic wave.

[0018] In one implementation, when the fingerprint recognition module is in the transmitting state, some electrode layers in the piezoelectric emitting layer are grounded, with two piezoelectric thin film layers spaced between adjacent grounded electrode layers. The ungrounded electrode layers in the piezoelectric emitting layer are coupled to the AC output terminal of the power supply module, and the voltage phase difference between the electrode layers coupled to two adjacent AC output terminals meets a preset range value. This connection method enables synchronous movement of multiple piezoelectric thin film layers, preventing opposite vibrations in the piezoelectric thin film layers within the piezoelectric emitting layer.

[0019] In one implementation, the piezoelectric emitting layer comprises two piezoelectric thin film layers. In the emitting state of the fingerprint recognition module, the electrode layer between the two piezoelectric thin film layers is grounded, while the ungrounded electrode layer is coupled to the AC output terminal of the power supply module. When the piezoelectric emitting layer comprises two piezoelectric thin film layers, the middle electrode layer is grounded, and the electrode layers on both sides are respectively connected to AC current with a phase difference, so that the two piezoelectric thin film layers in the piezoelectric emitting layer have voltages with different phases, causing the two piezoelectric thin film layers to vibrate in the same direction.

[0020] In one implementation, during the receiving state of the fingerprint recognition module, the electrode layers coupled to each piezoelectric thin film layer in the piezoelectric transmitting layer are disconnected. The piezoelectric receiving layer receives the ultrasonic signal and generates an electrical signal. The pixel circuit layer is connected to the piezoelectric receiving layer, acquires the electrical signal, and outputs it externally. During the receiving state, the piezoelectric receiving layer and the pixel circuit layer are connected, utilizing only the piezoelectric receiving layer to receive the ultrasonic signal. This avoids excessive piezoelectric thin film layers simultaneously receiving the signal, which could cause crosstalk to the electrical signal generated by the received ultrasonic signal.

[0021] In one implementation, when the fingerprint recognition module is in the receiving state, the electrode layer between the piezoelectric receiving layer and the piezoelectric transmitting layer is grounded to form a conductive circuit between the pixel circuit layer and the electrode layer coupled thereto. This allows the electrical signal generated by the piezoelectric receiving layer to be transmitted to the pixel circuit layer through the electrode layer. The pixel circuit layer then processes the electrical signal to form a fingerprint image signal in the pixel circuit layer for output.

[0022] In one implementation, the thickness of the electrode layer between any adjacent piezoelectric thin film layers is ≤λ / 10, where λ is the wavelength of the ultrasonic wave. During the reception of the ultrasonic signal by the piezoelectric receiving layer, the ultrasonic signal must penetrate each electrode layer and the piezoelectric emitting layer to reach the receiving layer. Reducing the thickness of the intermediate electrode layer to λ / 10 effectively reduces ultrasonic wave attenuation and improves signal reception strength.

[0023] In one implementation, the acoustic impedance difference between each electrode layer and the piezoelectric thin film layer is ≤2MRaly. Controlling the acoustic impedance difference between each electrode layer and the piezoelectric thin film layer within 2MRaly reduces ultrasonic signal reflection at various interfaces between the piezoelectric thin film layer and the electrode layer, thereby increasing signal reception strength.

[0024] In one implementation, the resistance of the electrode layer between any two adjacent piezoelectric thin film layers is ≤1Ω. The low resistance of the electrode layer between adjacent piezoelectric thin film layers reduces voltage drop across that portion of the electrode layer, thereby reducing energy consumption during emission.

[0025] Thirdly, this application provides an electronic device, which includes a control module, a power supply module, and a fingerprint recognition module of this application. The control module is electrically connected to both the power supply module and the fingerprint recognition module, and the power supply module is electrically connected to the fingerprint recognition module.

[0026] The electronic device in this application may be a terminal device, such as a mobile phone, tablet computer, laptop computer, desktop computer, gaming device, in-vehicle electronic device or wearable smart device, or other portable or mobile computing device, or an electronic database, automobile, bank ATM, or other electronic device.

[0027] Fourthly, this application provides a fingerprint recognition method applied to the fingerprint recognition module of the first aspect of this application, comprising:

[0028] When the fingerprint recognition module is in the transmitting state, the control module controls the power supply module to apply voltage between the second electrode layer and the third electrode layer so that the second piezoelectric thin film layer sends ultrasonic signals, and controls the first electrode layer and the second electrode layer to disconnect.

[0029] In one implementation, when the fingerprint recognition module is in the receiving state, the control module controls the second electrode layer and the third electrode layer to disconnect, the first piezoelectric thin film layer receives the ultrasonic signal and generates an electrical signal, the control module controls the pixel circuit layer to conduct with the first electrode layer, and controls the pixel circuit layer to take the electrical signal and output it to the outside.

[0030] Fifthly, this application provides a fingerprint recognition method, applied to the fingerprint recognition module of the second aspect of this application, comprising:

[0031] In the transmission state, the control module controls the power supply module to apply voltage between the electrode layers on both sides of each piezoelectric thin film layer in the piezoelectric transmitting layer so that the piezoelectric transmitting layer sends ultrasonic signals, and controls the electrode layers on both sides of the piezoelectric receiving layer to disconnect; wherein, the phase difference of the voltage applied between adjacent piezoelectric thin film layers in the piezoelectric transmitting layer meets a preset range value.

[0032] In one implementation, when the fingerprint recognition module is in the receiving state, the control module controls the power supply module to disconnect the electrode layers coupled to each piezoelectric thin film layer in the piezoelectric transmitting layer, the piezoelectric receiving layer receives the ultrasonic signal and generates an electrical signal, the control module controls the pixel circuit layer to be connected to the piezoelectric receiving layer, and controls the pixel circuit layer to acquire the electrical signal and output it to the outside.

[0033] Sixthly, this application provides a control device, which includes a processor and a memory; the memory stores computer-executable instructions; the processor executes the computer-executable instructions stored in the memory to cause the control device to perform the fingerprint recognition method of this application.

[0034] In a seventh aspect, this application provides a storage medium storing computer-executable instructions for causing a computer to execute the fingerprint recognition method of this application.

[0035] The technical effects achievable by aspects three through seven of this application can be referred to the corresponding effect descriptions in aspects one and two above, and will not be repeated here. Attached Figure Description

[0036] Figure 1 is a schematic diagram of the structure of a fingerprint recognition module according to an embodiment;

[0037] Figure 2 is a schematic diagram of the connection structure of a fingerprint recognition module in the transmitting state according to an embodiment;

[0038] Figure 3 is a schematic diagram of the connection structure of the fingerprint recognition module in the transmitting state according to another embodiment;

[0039] Figure 4 is a schematic diagram of the connection structure of a fingerprint recognition module in the receiving state according to an embodiment;

[0040] Figure 5 is a schematic diagram of the fingerprint recognition module according to another embodiment;

[0041] Figure 6 is a schematic diagram of the connection structure of a fingerprint recognition module in the transmitting state according to an embodiment;

[0042] Figure 7 is a connection diagram of an embodiment when the fingerprint recognition module is in the receiving state;

[0043] Figure 8 is a schematic diagram of the structure of a fingerprint recognition module according to an embodiment;

[0044] Figure 9 is a schematic diagram of the connection structure of a fingerprint recognition module in the transmitting state according to an embodiment;

[0045] Figure 10 is a schematic diagram of the connection structure of a fingerprint recognition module in the transmitting state according to an embodiment;

[0046] Figure 11 is a schematic diagram of the structure of an electronic device according to an embodiment;

[0047] Figure 12 is a schematic diagram of the structure of a control device according to one embodiment.

[0048] Reference numerals: 11-Substrate; 12-Pixel circuit layer; 13-Electrode layer; 131-First electrode layer; 132-Second electrode layer; 133-Third electrode layer; 134-Fourth electrode layer; 135-Fifth electrode layer; 136-Sixth electrode layer; 13n-Nth electrode layer; 14-Piezoelectric thin film layer; 141-First piezoelectric thin film layer; 142-Second piezoelectric thin film layer; 143-Third piezoelectric thin film layer; 144-Fourth piezoelectric thin film layer; 145-Fifth piezoelectric thin film layer; 146-Sixth piezoelectric thin film layer; 14n-Nth piezoelectric thin film layer; 15-Protective layer; 21-Piezoelectric receiving layer; 22-Piezoelectric emitting layer; 100-Fingerprint recognition module; 200-Control module; 300-Power supply module; 1000-Control device; 1001-Processor; 1002-Memory. Detailed Implementation

[0049] The terminology used in the following embodiments is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used in the specification and appended claims of this application, the singular expressions “a,” “an,” “the,” “the,” and “this” are intended to also include expressions such as “one or more,” unless the context clearly indicates otherwise.

[0050] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0051] Fingerprint recognition is now widely used in daily life, including but not limited to mobile phones, tablets, laptops, door locks, and bank cards. When a fingerprint is pressed, the fingerprint recognition module vibrates through a piezoelectric thin film layer to generate an ultrasonic signal. This ultrasonic signal is reflected by the fingerprint and then absorbed by the piezoelectric thin film layer to generate an electrical signal. The electrical signal generated by the piezoelectric thin film layer is transmitted to the pixel circuit layer, where it generates the corresponding fingerprint information. Existing fingerprint recognition modules typically apply voltage to both sides of the piezoelectric thin film layer through the pixel circuit layer. The pixel circuit layer generates parasitic resistance and capacitance in the voltage application circuit, thereby reducing the effective voltage applied to both ends of the piezoelectric thin film layer. Due to the voltage division effect of the pixel circuit layer, this leads to increased energy consumption and a decrease in sound pressure level.

[0052] To address the aforementioned issues, this application provides a fingerprint recognition module. This module utilizes two piezoelectric thin film layers: one serving as a piezoelectric receiving layer and the other as a piezoelectric emitting layer. In the emitting state, no voltage is applied to the piezoelectric receiving layer or the pixel circuit layer; instead, voltage is applied only to the two ends of the piezoelectric emitting layer. This avoids voltage division in the pixel circuit layer, reduces parasitic resistance and capacitance in the emitting circuit, thereby lowering energy consumption and increasing sound pressure.

[0053] Figure 1 is a schematic diagram of the structure of a fingerprint recognition module according to an embodiment. In this embodiment, the fingerprint recognition module has two piezoelectric thin film layers. As shown in Figure 1, the fingerprint recognition module of this embodiment includes a pixel circuit layer 12, a first electrode layer 131, a first piezoelectric thin film layer 141, a second electrode layer 132, a second piezoelectric thin film layer 142, and a third electrode layer 133 arranged sequentially. The first electrode layer 131, the first piezoelectric thin film layer 141, the second electrode layer 132, the second piezoelectric thin film layer 142, and the third electrode layer 133 are stacked sequentially and interconnected. The second electrode layer 132 is a single layer, connected to both the first piezoelectric thin film layer 141 and the second piezoelectric thin film layer 142. The first piezoelectric thin film layer 141 is electrically connected to the pixel circuit layer 12 through the first electrode layer 131. In addition, the fingerprint recognition module may also include a substrate 11, which is disposed on one side of the pixel circuit layer 12 and is used to support and protect the pixel circuit layer 12. The substrate 11 may be a silicon substrate 11, a glass substrate 11, or a flexible polymer resin substrate 11, etc.

[0054] The following explanation uses the orientation shown in Figure 1 as an example to illustrate the connection relationships between the various parts. All directional terms such as up and down mentioned below refer to the orientation shown in Figure 1 and are not specific location limitations.

[0055] The structure of the fingerprint recognition module is explained below from top to bottom, referring to Figure 1. As shown in Figure 1, the third electrode layer 133 and the second electrode layer 132 are respectively disposed on both sides of the second piezoelectric thin film layer 142, and are in contact with the second piezoelectric thin film layer 142 to form a conductive layer of the second piezoelectric thin film layer 142. The second piezoelectric thin film layer 142, as a piezoelectric emitting layer, mainly functions to generate ultrasonic signals and is the core component for converting electrical energy into acoustic energy. The third electrode layer 133 and the second electrode layer 132 on the upper and lower sides of the second piezoelectric thin film layer 142 can be planar layer structures, which can completely cover the upper and lower surfaces of the second piezoelectric thin film layer 142.

[0056] Below the second electrode layer 132 is the first piezoelectric thin film layer 141. The first piezoelectric thin film layer 141 serves as a piezoelectric receiving layer, used to receive ultrasonic signals and convert them into electrical signals. Below the first piezoelectric thin film layer 141 is the first electrode layer 131. The first electrode layer 131 and the second electrode layer 132 form two conductive layers of the first piezoelectric thin film layer 141, used to energize the first piezoelectric thin film layer 141. The first piezoelectric thin film layer 141 is mainly used to receive ultrasonic signals reflected back by fingerprints, deform to generate electrical signals, and realize the conversion of acoustic energy into electrical energy.

[0057] Referring again to Figure 1, the pixel circuit layer 12 is disposed below the first electrode layer 131. The pixel circuit layer 12 can be disposed on the surface of the substrate 11 or embedded in the substrate 11. The pixel circuit layer 12 is an array structure, including multiple pixel units. Each pixel unit can be composed of multiple transistors. The pixel circuit layer 12 mainly functions to read echo signals and generate fingerprint image information. The first electrode layer 131 can be disposed on the surface of the substrate 11 or embedded in the substrate 11. For example, the first electrode layer 131 can be directly exposed on the surface of the substrate 11, or it can be protected by a very thin dielectric material. For example, a dielectric material can be disposed between the first electrode layer 131 and the first piezoelectric thin film layer 141 to increase the adhesion between the first piezoelectric thin film layer 141 and the first electrode layer 131. The first electrode layer 131 is also an array structure and can be composed of sublayers arranged in an array. Each sub-layer in the first electrode layer 131 can be connected one-to-one with each pixel unit in the pixel circuit layer 12, that is, each sub-layer of the first electrode layer 131 is connected to a pixel unit in the pixel circuit layer 12 to meet the imaging requirements and partition fingerprint information.

[0058] In this embodiment, the materials of the first electrode layer 131, the second electrode layer 132, and the third electrode layer 133 can each be independently a metal conductive layer such as Au, Al, Cu, or Pt, an inorganic conductive layer such as ITO, an organic conductive layer such as a mixture of poly3,4-ethylenedioxythiophene PEDOT and propylene glycol alginate sodium sulfate (PSS), graphite, graphene, or a composite conductive layer such as Ag and ACF.

[0059] Both the first piezoelectric thin film layer 141 and the second piezoelectric thin film layer 142 can be organic piezoelectric thin film layers, such as piezoelectric thin film layers formed by polyvinylidene difluoride (PVDF), polyvinylidene difluoride-trifluoroethene (PVDF-trFE), polyvinylidene difluoride-trifluoroethene-chlorofluoroethylene (PVDF-trFE-CFE), and their composites.

[0060] Referring again to Figure 1, the fingerprint recognition module of this embodiment, in addition to the structure described above, may also include a protective layer 15. The protective layer 15 is disposed on the surface of the third electrode layer 133 and is used to protect the third electrode layer 133, for example, protecting the third electrode layer 133 and the underlying structure from oxidation and moisture erosion, thereby improving the long-term stability of the fingerprint recognition module. The protective layer 15 can be a single layer or multiple layers, and its material can be a high-polymer material or a metal adhesive with an insulating layer, etc.

[0061] In the fingerprint recognition module of this application embodiment, in the transmitting state, a voltage is applied between the second electrode layer 132 and the third electrode layer 133 to cause the second piezoelectric thin film layer 142 to vibrate and generate an ultrasonic signal, and the first electrode layer 131 and the second electrode layer 132 are disconnected, that is, no voltage is applied between the first electrode layer 131 and the second electrode layer 132. In this state, the first piezoelectric thin film layer 141 does not generate ultrasonic waves. In the transmitting state of the fingerprint recognition module, the first electrode layer 131 and the pixel circuit layer 12 can also be in a disconnected state, that is, no current flows between the first piezoelectric thin film layer 141 and the pixel circuit layer 12.

[0062] Figure 2 is a schematic diagram of the connection structure of the fingerprint recognition module in the transmitting state according to one embodiment. In the transmitting state of the fingerprint recognition module, an AC current can be used to apply a voltage to the second piezoelectric thin film layer 142. As shown in Figure 2, when AC current is applied to the second piezoelectric thin film layer 142, the second electrode layer 132 is grounded, and the third electrode layer 133 is coupled to the AC output terminal of the power supply module. Figure 3 is a schematic diagram of the connection structure of the fingerprint recognition module in the transmitting state according to another embodiment. As shown in Figure 3, in another embodiment, the third electrode layer 133 is grounded, and the second electrode layer 132 is coupled to the AC output terminal of the power supply module. Tx in Figures 2 and 3 represents the input signal. In both of these connection methods, a certain voltage can be applied to both ends of the second piezoelectric thin film layer 142 to cause the second piezoelectric thin film layer 142 to vibrate and generate an ultrasonic signal.

[0063] In the transmitting state of the fingerprint recognition module, since a voltage needs to be applied between the second electrode layer 132 and the third electrode layer 133, the resistance of both the second and third electrode layers 132 is ≤1Ω to reduce the parasitic resistance generated by the second and third electrode layers 133 in the circuit. The low resistance of the second and third electrode layers 132 reduces the voltage division between them, allowing more voltage drop to be applied to the second piezoelectric thin film layer 142, thereby increasing the transmitted sound pressure and reducing energy consumption in the transmitting state.

[0064] In the receiving state of the fingerprint recognition module, the second electrode layer 132 and the third electrode layer 133 are disconnected. The first piezoelectric thin film layer 141 receives the ultrasonic signal and generates an electrical signal. The pixel circuit layer 12 is connected to the first electrode layer 131 and acquires the electrical signal for external output. In the receiving state of the fingerprint recognition module, only the first piezoelectric thin film layer 141 is used to receive the ultrasonic signal, avoiding excessive piezoelectric thin film layers receiving the signal simultaneously, which could cause crosstalk to the electrical signal generated by the received ultrasonic signal.

[0065] Figure 4 is a schematic diagram of the connection structure of a fingerprint recognition module in the receiving state according to an embodiment. As shown in Figure 4, in the receiving state of the fingerprint recognition module, the second electrode layer 132 is grounded. After receiving the ultrasonic signal, the first piezoelectric film layer 141 generates an electrical signal based on the ultrasonic signal. When the second electrode layer 132 is grounded, the potential of the first electrode layer 131 is higher than that of the second electrode layer 132. Due to the potential difference, the electrical signal in the first electrode layer 131 can be transmitted to the pixel circuit layer 12 to form a conductive circuit between the pixel circuit layer 12 and the first electrode layer 131. After acquiring the above electrical signal, the pixel circuit layer 12 processes it to form a fingerprint image signal for output. Rx in Figure 4 represents the output signal. The pixel circuit layer 12 is connected to external devices for signal output. For example, the pixel circuit layer 12 can be connected to a control module to transmit the processed signal generated by the pixel circuit layer 12 to the control module.

[0066] In this embodiment, the second piezoelectric thin film layer 142 and the first piezoelectric thin film layer 141 have the same polarization direction. During the fabrication of the fingerprint recognition module, after forming the first piezoelectric thin film layer 141 and the second piezoelectric thin film layer 142, they need to be polarized to acquire piezoelectric properties. If the polarization directions of the first piezoelectric thin film layer 141 and the second piezoelectric thin film layer 142 are different, different polarization devices are required for polarization processing, increasing costs. To simplify the polarization process, reduce polarization costs, and improve polarization efficiency, in this embodiment, the first piezoelectric thin film layer 141 and the second piezoelectric thin film layer 142 have the same polarization direction. The polarization directions of both layers can simultaneously face the protective layer 15 or the substrate 11.

[0067] During one operation of the fingerprint recognition module, when a finger presses on the recognition area of ​​the protective layer 15, the fingerprint recognition module is triggered. The control module controls the power supply module to apply voltage to the second piezoelectric film layer 142, generating ultrasonic waves. Subsequently, the control module controls the power supply module to stop applying voltage to the second piezoelectric film layer 142, disconnecting the third electrode layer 133 from the second electrode layer 132. After being reflected by the fingerprint, the ultrasonic waves pass through the protective layer 15, the third electrode layer 133, the second piezoelectric film layer 142, and the second electrode layer 132 before entering the first piezoelectric film layer 141. The first piezoelectric film layer 141 receives the reflected ultrasonic waves and vibrates to generate an electrical signal. At this time, the control module can control the second electrode layer 132 to ground, creating a voltage difference between the second electrode layer 132 and the first electrode layer 131. The electrical signal between the first electrode layer 131 and the pixel signal layer is transmitted to the pixel circuit layer 12. In the receiving state, the ultrasonic signal must pass through the second electrode layer 132 before being transmitted to the first piezoelectric thin film layer 141. Therefore, the second electrode layer 132 will have a certain impact on the attenuation of the ultrasonic wave during this process. Furthermore, when the fingerprint recognition module uses a back-mounted design, in the transmitting state, the emitted ultrasonic signal will penetrate the second electrode layer 132. To reduce the attenuation caused by the second electrode layer 132, the thickness of the second electrode layer 132 should be ≤λ / 10, where λ is the wavelength of the ultrasonic wave. Reducing the thickness of the second electrode layer 132 to λ / 10 can reduce the attenuation of the ultrasonic wave, improve the transmission intensity and reception intensity of the ultrasonic signal, and a thinner electrode thickness can reduce the attenuation of the ultrasonic wave during transmission within the electrode, thereby improving the transmission efficiency of the ultrasonic wave.

[0068] Furthermore, in the receiving state, ultrasonic waves are reflected at the interfaces of heterogeneous structures. To reduce interface reflection, in one implementation, the acoustic impedance difference between the first electrode layer 131, the second electrode layer 132, and the third electrode layer 133 and the first piezoelectric thin film layer 141 is ≤2MRaly; for example, ≤1MRaly, ≤0.5MRaly, or ≤0.2MRaly. The acoustic impedance difference between the first electrode layer 131, the second electrode layer 132, and the third electrode layer 133 and the second piezoelectric thin film layer 142 is ≤2MRaly, for example, ≤1MRaly, ≤0.5MRaly, or ≤0.2MRaly. Controlling the acoustic impedance difference between each electrode layer and the first piezoelectric thin film layer 141 and the second piezoelectric thin film layer 142 within 2MRaly, and especially within 0.2MRaly, can significantly reduce the reflection of ultrasonic signals at each interface, reduce ultrasonic wave transmission attenuation, and thus increase signal reception strength.

[0069] When the fingerprint recognition module is in the receiving state, the electrical signal generated by the first piezoelectric thin film layer 141 needs to be transmitted to the pixel circuit layer 12 through the first electrode layer 131. A conductive circuit needs to be formed between the first electrode layer 131 and the pixel circuit layer 12. Therefore, the resistance of the first electrode layer 131 cannot be too high, otherwise it will affect the resistance of the conductive circuit. In this embodiment, the resistance of the first electrode layer 131 should be ≤1Ω.

[0070] Figure 5 is a schematic diagram of the fingerprint recognition module according to another embodiment. As shown in Figure 5, the fingerprint recognition module of this embodiment includes a pixel circuit layer 12, a piezoelectric receiving layer 21, and a piezoelectric emitting layer 22 arranged sequentially. The piezoelectric emitting layer 22 includes at least two piezoelectric thin film layers 14 with the same polarization direction. Each piezoelectric thin film layer 14 has an electrode layer 13 on both sides, and adjacent piezoelectric thin film layers 14 share a common electrode layer 13. The piezoelectric receiving layer 21 and the pixel circuit layer 12 are electrically connected through the electrode layer 13. In the emitting state of the fingerprint recognition module, a voltage is applied between the electrode layers 13 on both sides of each piezoelectric thin film layer 14 in the piezoelectric emitting layer 22 to generate an ultrasonic signal, and the electrode layers 13 on both sides of the piezoelectric receiving layer 21 are disconnected. The phase difference of the voltage applied between adjacent piezoelectric thin film layers 14 in the piezoelectric emitting layer 22 satisfies a preset range value. When the fingerprint recognition module is in the transmitting state, the piezoelectric receiving layer 21 and the pixel circuit layer 12 can also be in a disconnected state, and no current flows between each piezoelectric thin film layer in the piezoelectric receiving layer 21 and the pixel circuit layer.

[0071] In the fingerprint recognition module shown in Figure 5, during the emission state, only the two ends of the piezoelectric thin film layer 14 in the piezoelectric emission layer 22 are voltage-applied. That is, during the emission state, only the piezoelectric thin film layer 14 in the piezoelectric emission layer 22 is in a vibrating state, capable of generating ultrasonic waves. Since the piezoelectric emission layer 22 has at least two piezoelectric thin film layers 14, the polarization directions of each piezoelectric thin film layer 14 are consistent, and adjacent piezoelectric thin film layers 14 share a common electrode layer 13. During the emission state, to ensure that the vibration directions of each piezoelectric thin film layer 14 are consistent and to achieve synchronous vibration, voltages with different phases can be applied to both sides of adjacent piezoelectric thin film layers 14. The phase of the applied voltages satisfies a preset range value. In one embodiment, the preset range value is 180±45°, for example, 180±30°, 180±20°, 180±10°, or a phase difference of 180°. By applying a voltage with a 180° phase difference, adjacent piezoelectric thin film layers can be made to vibrate synchronously in the same direction, achieving resonance and maximizing the amplitude of the generated ultrasonic waves, thereby increasing the ultrasonic wave emission intensity.

[0072] The piezoelectric thin film layer 14 in the piezoelectric emitting layer 22 can have multiple layers. For example, the piezoelectric thin film layer 14 in the piezoelectric emitting layer 22 can have 2, 3, 4, 5, or 6 or more layers.

[0073] The piezoelectric receiving layer 21 may include a piezoelectric thin film layer 14. The polarization direction of the piezoelectric thin film layer 14 in the piezoelectric receiving layer 21 is the same as that in the piezoelectric emitting layer 22, so as to simplify the polarization process and reduce the polarization cost.

[0074] The structure of the pixel circuit layer 12, the piezoelectric thin film layer 14 in the piezoelectric emitting layer 22, the piezoelectric thin film layer 14 in the piezoelectric receiving layer 21, and the materials of the electrode layer 13 in the fingerprint recognition module shown in Figure 5 are the same as those in the fingerprint recognition module shown in Figure 2, and will not be repeated here. In addition, the fingerprint recognition module of this embodiment also includes a substrate 11 and a protective layer 15. The structure of the substrate 11 and the protective layer 15 is the same as that in the fingerprint recognition module shown in Figure 2, and will not be repeated here.

[0075] In the transmitting state of the fingerprint recognition module, in order to generate ultrasonic signals in the piezoelectric transmitting layer 22, the electrodes on both sides of the piezoelectric receiving layer 21 are disconnected, and part of the electrode layer 13 in the piezoelectric transmitting layer 22 is grounded. The two adjacent electrode layers used for grounding are separated by two piezoelectric thin film layers. The ungrounded electrode layer 13 in the piezoelectric transmitting layer 22 is coupled to the AC output terminal of the power supply module, and the voltage phase difference of the electrode layers coupled to the two adjacent AC output terminals meets the preset range value.

[0076] Figure 6 is a schematic diagram of the connection structure of a fingerprint recognition module in the transmitting state according to an embodiment. As shown in Figure 6, the fingerprint recognition module includes n piezoelectric thin film layers, which are respectively labeled as the first piezoelectric thin film layer 141, the second piezoelectric thin film layer 142, the third piezoelectric thin film layer 143, the fourth piezoelectric thin film layer 144, the fifth piezoelectric thin film layer 145, the sixth piezoelectric thin film layer 146, ..., the nth piezoelectric thin film layer 14n. The first piezoelectric thin film layer 141 serves as the piezoelectric receiving layer 21. The remaining piezoelectric thin film layers, such as the second piezoelectric thin film layer 142, the third piezoelectric thin film layer 143, the fourth piezoelectric thin film layer 144, the fifth piezoelectric thin film layer 145, the sixth piezoelectric thin film layer 146, ..., the nth piezoelectric thin film layer 14n, serve as the piezoelectric transmitting layer 22. The electrode layer between the piezoelectric receiving layer 21 and the piezoelectric transmitting layer 22 is the first electrode layer 131. In the piezoelectric emitting layer 22, the electrode layers on both sides of each piezoelectric thin film layer are sequentially labeled from bottom to top as the second electrode layer 132, the third electrode layer 133, the fourth electrode layer 134, the fifth electrode layer 135, the sixth electrode layer 136, ..., the nth electrode layer 13n. When the fingerprint recognition module is in the emitting state, the electrode layers on both sides of the first piezoelectric thin film layer 141 in the piezoelectric receiving layer 21 are disconnected, that is, the first electrode layer 131 and the second electrode layer 132 are disconnected. Some electrode layers in the piezoelectric emitting layer 22, such as the third electrode layer 133 and the fifth electrode layer 135 as shown in Figure 6, are grounded. Two adjacent electrode layers used for grounding, such as the third electrode layer 133 and the fifth electrode layer 135, are separated by two piezoelectric thin film layers. The two separated piezoelectric thin film layers are the third piezoelectric thin film layer 143 and the fourth piezoelectric thin film layer 144.

[0077] Ungrounded electrode layers, such as the second electrode layer 132, the fourth electrode layer 134, and the sixth electrode layer 136, are coupled to the AC output terminals of the power supply module. Electrode layers coupled to two adjacent AC output terminals, such as the second electrode layer 132 and the fourth electrode layer 134 being adjacent electrode layers coupled to two AC output terminals, and the fourth electrode layer 134 and the sixth electrode layer 136 being adjacent electrode layers coupled to two AC output terminals, have a voltage phase difference that satisfies the preset range value; that is, the voltage phase difference between the second electrode layer 132 and the fourth electrode layer 134 satisfies the preset range value; the voltage phase difference between the fourth electrode layer 134 and the sixth electrode layer 136 satisfies the preset range value. In Figure 6, Tx_1 is the first input signal, and Tx_2 is the second input signal. Both the first and second input signals are AC signals, and the voltage phase difference between them satisfies the preset range value. In adjacent electrode layers of two coupled AC output terminals, such as the second electrode layer 132 and the fourth electrode layer 134, Tx_1 can be input to the second electrode layer 132 and Tx_2 can be input to the fourth electrode layer 134; in the fourth electrode layer 134 and the sixth electrode layer 136, Tx_2 can be input to the fourth electrode layer 134 and Tx_1 can be input to the sixth electrode layer 136.

[0078] Figure 7 is a connection diagram of an embodiment when the fingerprint recognition module is in the receiving state. As shown in Figure 7, when the fingerprint recognition module is in the receiving state, the electrode layers 13 on both sides of each piezoelectric thin film layer 14 of the piezoelectric emitting layer 22 are disconnected, such as the second electrode layer 132, the third electrode layer 133, the fourth electrode layer 134, the fifth electrode layer 135, the sixth electrode layer 136, ..., the nth electrode layer 13n are all disconnected. The electrode layer between the piezoelectric receiving layer 21 and the piezoelectric emitting layer 22, such as the second electrode layer 132, is grounded. The piezoelectric receiving layer 21 receives ultrasonic signals and generates electrical signals. The pixel circuit layer 12 is connected to the piezoelectric receiving layer 21 through the first electrode layer 131. The pixel circuit layer 12 acquires the electrical signals and outputs them externally.

[0079] In the piezoelectric emission layer, taking two piezoelectric thin film layers as an example, the connection structure of the fingerprint recognition module in this application embodiment will be explained.

[0080] Figure 8 is a schematic diagram of the structure of a fingerprint recognition module according to an embodiment. As shown in Figure 8, the fingerprint recognition module includes three piezoelectric thin film layers, referred to as a first piezoelectric thin film layer 141, a second piezoelectric thin film layer 142, and a third piezoelectric thin film layer 143. The first piezoelectric thin film layer 141 is connected to the pixel circuit layer 12 through a first electrode layer 131, and the second piezoelectric thin film layer 142 is disposed between the first piezoelectric thin film layer 141 and the third piezoelectric thin film layer 143. The first piezoelectric thin film layer 141 is used as a piezoelectric receiving layer. The second piezoelectric thin film layer 142 and the third piezoelectric thin film layer 143 are used as piezoelectric emitting layers. The electrode between the first piezoelectric thin film layer 141 and the second piezoelectric thin film layer 142 is referred to as the second electrode layer 132. The electrode layer between the second piezoelectric thin film layer 142 and the third piezoelectric thin film layer 143 is referred to as the third electrode layer 133. The electrode layer between the third piezoelectric thin film layer 143 and the protective layer 15 is referred to as the fourth electrode layer 134.

[0081] Since adjacent piezoelectric thin film layers in the piezoelectric emitting layer share a common electrode layer, and the polarization directions of each piezoelectric thin film layer are the same, to avoid completely opposite vibrations between the piezoelectric thin film layers, an alternating current is coupled in to control the pressure direction of adjacent piezoelectric thin film layers, so that the adjacent piezoelectric thin film layers vibrate in the same direction.

[0082] Figure 9 is a schematic diagram of the connection structure of a fingerprint recognition module in the transmitting state according to an embodiment. As shown in Figure 9, when the fingerprint recognition module is in the transmitting state, the third electrode layer 133 between the second piezoelectric film 142 and the third piezoelectric film 143 in the piezoelectric transmitting layer 22 is grounded. The ungrounded electrode layers, such as the second electrode layer 132 and the fourth electrode layer 134, are coupled to the AC output terminal of the power supply module. The second electrode layer 132 and the fourth electrode layer 134 are respectively coupled to the AC output terminals of different phases of the power supply module. The phase difference of the voltages applied to the second electrode layer 132 and the fourth electrode layer 134 is within a preset range, such as a phase difference of 180°. No voltage is applied to the first electrode layer 131 between the first piezoelectric film layer 141 and the pixel circuit layer 12 in the piezoelectric receiving layer 21.

[0083] Figure 10 is a schematic diagram of the connection structure of a fingerprint recognition module in the transmitting state according to an embodiment. As shown in Figure 10, when the fingerprint recognition module is in the receiving state, the electrode layer between the piezoelectric receiving layer 21 and the piezoelectric transmitting layer 22, such as the second electrode layer 132, is grounded. The grounding of the second electrode layer 132 forms a conductive circuit between the pixel circuit layer and the first electrode layer 131, allowing the electrical signal generated by the piezoelectric receiving layer to be transmitted to the pixel circuit layer 12. After acquiring the above electrical signal, the pixel circuit layer 12 processes it to form a fingerprint image signal for output. The pixel circuit layer 12 is connected to external devices for signal output, such as a control module, to transmit the processed signal generated by the pixel circuit layer 12 to the control module.

[0084] In the structures shown in Figures 5 to 10, to reduce the attenuation of ultrasonic waves in the electrode layers, the thickness of the electrode layer 13 between any adjacent piezoelectric thin film layers 14 is ≤λ / 10, where λ is the wavelength of the ultrasonic wave. Reducing the thickness of the electrode layer 13 to λ / 10 can reduce the attenuation of ultrasonic waves and improve the signal reception strength. A thinner electrode layer thickness can reduce the attenuation of ultrasonic waves during transmission within the electrode, thereby improving the transmission efficiency of ultrasonic waves. The resistance of each electrode layer is ≤1Ω to reduce the voltage drop across the electrode layers.

[0085] The acoustic impedance difference between each electrode layer 13 and the piezoelectric thin film layer 14 is ≤2MRaly. For example, ≤1MRaly, ≤0.5MRaly, or ≤0.2MRaly. The acoustic impedance difference between the first electrode layer 131, the second electrode layer 132, and the third electrode layer 133 and the piezoelectric receiving layer is also ≤2MRaly, for example, ≤1MRaly, ≤0.5MRaly, or ≤0.2MRaly. Controlling the acoustic impedance difference between each electrode layer and the piezoelectric receiving and emitting layers within 2MRaly, especially within 0.2MRaly, can significantly reduce the reflection of ultrasonic signals at various interfaces, reduce the transmission attenuation of ultrasonic waves, and thus increase the signal reception strength.

[0086] Based on the same technical objective, this application provides an electronic device. Figure 11 is a schematic diagram of the structure of an electronic device according to an embodiment. As shown in Figure 11, the electronic device may include a control module 200, a power supply module 300, and a fingerprint recognition module 100 according to this application embodiment. The control module 200 is electrically connected to both the power supply module 300 and the fingerprint recognition module 100. The power supply module 300 is also electrically connected to the fingerprint recognition module 100.

[0087] Based on the same technical objective, this application provides a fingerprint recognition method. This fingerprint recognition method is applied to the fingerprint recognition module with the structure shown in Figures 2 to 5 of this application and may include the following steps: In the transmitting state of the fingerprint recognition module, the control module controls the power supply module to apply a voltage between the second electrode layer and the third electrode layer to make the second piezoelectric thin film layer send an ultrasonic signal, and controls the first electrode layer and the second electrode layer to disconnect.

[0088] In addition, when the fingerprint recognition module is in the receiving state, the control module controls the second electrode layer and the third electrode layer to disconnect. The first piezoelectric thin film layer receives the reflected ultrasonic signal and generates an electrical signal. The control module controls the pixel circuit layer to be connected to the first electrode layer and controls the pixel circuit layer to acquire the electrical signal and output it to the outside.

[0089] Based on the same technical objective, this application provides a fingerprint recognition method. This fingerprint recognition method is applied to the fingerprint recognition module with the structure shown in Figures 6 to 8 of this application and may include the following steps: In the transmitting state of the fingerprint recognition module, the control module controls the power supply module to apply a voltage between the electrode layers on both sides of each piezoelectric thin film layer in the piezoelectric transmitting layer, so that the piezoelectric transmitting layer sends an ultrasonic signal, and controls the electrode layers on both sides of the piezoelectric receiving layer to disconnect; wherein, the phase difference of the voltage applied between adjacent piezoelectric thin film layers of the piezoelectric transmitting layer satisfies a preset range value.

[0090] In addition, when the fingerprint recognition module is in the receiving state, the control module controls the power supply module to disconnect the electrode layer coupled to each piezoelectric thin film layer in the piezoelectric emitting layer, and the piezoelectric receiving layer receives the ultrasonic signal and generates an electrical signal; the control module controls the pixel circuit layer to be connected to the piezoelectric receiving layer, and controls the pixel circuit layer to acquire the electrical signal and output it to the outside.

[0091] Based on the same technical objective, this application also provides a control device, which includes a processor and a memory; the memory stores computer-executable instructions; the processor is used to execute the computer-executable instructions stored in the memory, so that the control device performs the fingerprint recognition method of this application.

[0092] Figure 12 is a schematic diagram of the structure of a control device according to one embodiment. As shown in Figure 12, in some embodiments, the structure of the control device 1000 may include a processor 1001 and a memory 1002 connected to the processor 1001. The processor 1001 and the memory 1002 can be interconnected via a bus, which may be a PCI bus or an EISA bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc.

[0093] The memory 1002 can be used to store software programs and modules. The processor 1001 executes various functional applications and data processing of the control device 1000 by running the software programs and modules stored in the memory 1002, such as the device operation control method provided in the embodiments of this application.

[0094] The memory 1002 may primarily include a program storage area and a data storage area. The program storage area may store the operating system, application programs of at least one application, etc.; the data storage area may be used to store user data, etc. In addition, the memory 1002 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0095] The processor 1001 in the control device 1000 is used to run computer instructions or programs stored in the memory 1002 to perform the functions in any of the above method embodiments. In some embodiments, the processor 1001 may include one or more processing units, such as a PLC, CPU, GPU, DSP, FPGA, PLA, and / or NPU. Different processing units may be independent devices or integrated into one or more processors. The processor 1001 may also include a controller, which can generate operation control signals according to the instruction opcode and timing signals to control the instruction fetching and execution.

[0096] In one embodiment, the control device 1000 may further include a communication module, which can be used to communicate with a data acquisition device or an execution device. The communication module may be a communication chip.

[0097] It is understood that the structures illustrated in the embodiments of this application do not constitute a specific limitation on the control device. In other embodiments of this application, the control device may include more or fewer components than illustrated, or combine some components, or split some components, or have different component arrangements. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

[0098] For the same technical purpose, this application also provides a storage medium storing computer-executable instructions for causing a computer to execute the fingerprint recognition method of this application.

[0099] The computer-readable storage medium provided in the embodiments of this application may be random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), register, hard disk, portable hard disk, CD-ROM, or any other form of computer-readable storage medium known in the art.

[0100] Computer-executable instructions can be stored in or transferred from one computer-readable storage medium to another. For example, a computer program or instructions can be transferred from one website, computer, server, or data center to another via wired or wireless means. A computer-readable storage medium can be any usable medium that a computer can access, or a data storage device such as a server or data center that integrates one or more usable media. Usable media can be magnetic media, such as floppy disks, hard disks, and magnetic tapes; optical media, such as digital video discs (DVDs); or semiconductor media, such as solid-state drives (SSDs).

[0101] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A fingerprint recognition module, characterized in that, It includes a pixel circuit layer, a first electrode layer, a first piezoelectric thin film layer, a second electrode layer, a second piezoelectric thin film layer, and a third electrode layer arranged sequentially, wherein the first piezoelectric thin film layer is electrically connected to the pixel circuit layer through the first electrode layer; The first piezoelectric thin film layer and the second piezoelectric thin film layer have the same polarization direction; In the transmitting state of the fingerprint recognition module, a voltage is applied between the second electrode layer and the third electrode layer to cause the second piezoelectric thin film layer to generate an ultrasonic signal, and the first electrode layer and the second electrode layer are disconnected.

2. The fingerprint recognition module according to claim 1, characterized in that, In the transmitting state of the fingerprint recognition module, the second electrode layer is grounded, and the third electrode layer is coupled to the AC output terminal of the power supply module; Alternatively, the third electrode layer is grounded, and the second electrode layer is coupled to the AC output terminal of the power supply module.

3. The fingerprint recognition module according to claim 1 or 2, characterized in that, When the fingerprint recognition module is in the receiving state, the second electrode layer and the third electrode layer are disconnected, the first piezoelectric thin film layer receives the ultrasonic signal and generates an electrical signal, the pixel circuit layer is connected to the first electrode layer, and the pixel circuit layer acquires the electrical signal and outputs it to the outside.

4. The fingerprint recognition module according to claim 3, characterized in that, In the receiving state of the fingerprint recognition module, the second electrode layer is grounded.

5. The fingerprint recognition module according to any one of claims 1-4, characterized in that, The thickness of the second electrode layer is ≤λ / 10, where λ is the wavelength of the ultrasonic wave.

6. The fingerprint recognition module according to any one of claims 1-5, characterized in that, The acoustic impedance differences between the first electrode layer, the second electrode layer, and the third electrode layer and the second piezoelectric thin film layer are all ≤2MRaly; the acoustic impedance differences between the first electrode layer, the second electrode layer, and the third electrode layer and the first piezoelectric thin film layer are all ≤2MRaly.

7. The fingerprint recognition module according to any one of claims 1-6, characterized in that, The resistance of the first electrode layer, the second electrode layer, and the third electrode layer is ≤1Ω.

8. A fingerprint recognition module, characterized in that, The device includes a pixel circuit layer, a piezoelectric receiving layer, and a piezoelectric emitting layer arranged sequentially. The piezoelectric emitting layer includes at least two piezoelectric thin film layers with the same polarization direction. Each piezoelectric thin film layer has an electrode layer on both sides, and adjacent piezoelectric thin film layers share a common electrode layer. The piezoelectric receiving layer is electrically connected to the pixel circuit layer through the electrode layer. In the transmitting state of the fingerprint recognition module, a voltage is applied between the electrode layers on both sides of each piezoelectric thin film layer in the piezoelectric transmitting layer to generate an ultrasonic signal, and the electrode layers on both sides of the piezoelectric receiving layer are disconnected; wherein, the phase difference of the voltage applied between adjacent piezoelectric thin film layers in the piezoelectric transmitting layer satisfies a preset range value.

9. The fingerprint recognition module according to claim 8, characterized in that, The preset range value is 180±45°.

10. The fingerprint recognition module according to claim 8 or 9, characterized in that, In the emission state of the fingerprint recognition module, a portion of the electrode layer in the piezoelectric emission layer is grounded, and two piezoelectric thin film layers are spaced apart between two adjacent electrode layers used for grounding. The ungrounded electrode layer in the piezoelectric emission layer is coupled to the AC output terminal of the power supply module, and the voltage phase difference between the electrode layers coupled to two adjacent AC output terminals satisfies the preset range value.

11. The fingerprint recognition module according to any one of claims 8-10, characterized in that, The piezoelectric emitting layer includes two piezoelectric thin film layers. In the emitting state of the fingerprint recognition module, the electrode layer between the two piezoelectric thin film layers is grounded, and the ungrounded electrode layer is coupled to the AC output terminal of the power supply module.

12. The fingerprint recognition module according to any one of claims 8-11, characterized in that, In the receiving state of the fingerprint recognition module, the electrode layers coupled to each piezoelectric thin film layer in the piezoelectric emitting layer are disconnected. The piezoelectric receiving layer receives ultrasonic signals and generates electrical signals. The pixel circuit layer is connected to the piezoelectric receiving layer and acquires the electrical signals and outputs them to the outside.

13. The fingerprint recognition module according to claim 12, characterized in that, In the receiving state of the fingerprint recognition module, the electrode layer between the piezoelectric receiving layer and the piezoelectric emitting layer is grounded.

14. The fingerprint recognition module according to any one of claims 8-13, characterized in that, The thickness of the electrode layer between any two adjacent piezoelectric thin film layers is ≤λ / 10, where λ is the wavelength of the ultrasonic wave.

15. The fingerprint recognition module according to any one of claims 8-14, characterized in that, The difference in acoustic impedance between each electrode layer and each piezoelectric thin film layer is ≤2MRaly.

16. The fingerprint recognition module according to any one of claims 8-15, characterized in that, The resistance of each electrode layer is ≤1Ω.

17. An electronic device, characterized in that, It includes a control module, a power supply module, and a fingerprint recognition module as described in any one of claims 1-16, wherein the control module is electrically connected to both the power supply module and the fingerprint recognition module, and the power supply module is electrically connected to the fingerprint recognition module.

18. A fingerprint recognition method, characterized in that, Applied to the fingerprint recognition module as described in any one of claims 1-7, comprising: In the transmitting state of the fingerprint recognition module, the control module controls the power supply module to apply voltage between the second electrode layer and the third electrode layer to make the second piezoelectric thin film layer send ultrasonic signals, and controls the first electrode layer and the second electrode layer to disconnect.

19. The fingerprint recognition method according to claim 18, characterized in that, In the receiving state of the fingerprint recognition module, the control module controls the second electrode layer and the third electrode layer to disconnect, the first piezoelectric thin film layer receives the ultrasonic signal and generates an electrical signal, the control module controls the pixel circuit layer to be connected to the first electrode layer, and controls the pixel circuit layer to acquire the electrical signal and output it to the outside.

20. A fingerprint recognition method, characterized in that, The fingerprint recognition module as described in any one of claims 8-16 includes: In the transmitting state of the fingerprint recognition module, the control module controls the power supply module to apply voltage between the electrode layers on both sides of each piezoelectric thin film layer in the piezoelectric transmitting layer, so that the piezoelectric transmitting layer sends ultrasonic signals, and controls the electrode layers on both sides of the piezoelectric receiving layer to disconnect; wherein, the phase difference of the voltage applied between adjacent piezoelectric thin film layers in the piezoelectric transmitting layer meets a preset range value.

21. The fingerprint recognition method according to claim 20, characterized in that, In the receiving state of the fingerprint recognition module, the control module controls the power supply module to disconnect the electrode layer coupled to each piezoelectric thin film layer in the piezoelectric emitting layer. The piezoelectric receiving layer receives ultrasonic signals and generates electrical signals. The control module controls the pixel circuit layer to conduct with the piezoelectric receiving layer and controls the pixel circuit layer to acquire the electrical signals and output them externally.

22. A control device, characterized in that, It includes a processor and a memory; the memory stores computer-executable instructions; the processor is configured to execute the computer-executable instructions stored in the memory so that the control device performs the fingerprint recognition method as described in any one of claims 18-21.

23. A storage medium, characterized in that, The device stores computer-executable instructions for causing a computer to perform the fingerprint recognition method as described in any one of claims 18-21.

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