An ultrasonic fingerprint identification module, system and electronic device

Abstract

This application provides an ultrasonic fingerprint recognition module, system, and electronic device. The ultrasonic fingerprint recognition module includes: a common electrode, a piezoelectric layer, and a circuit board stacked together. The circuit board includes multiple pixel electrode units arranged in an array near the piezoelectric layer. Each pixel electrode unit corresponds to a pixel, and each pixel electrode unit includes N first pixel electrodes and M second pixel electrodes. One side of the piezoelectric layer is electrically connected to the common electrode, and the other side of the piezoelectric layer is electrically connected to the multiple pixel electrode units. When the ultrasonic fingerprint recognition module is in transmitting mode, the N first pixel electrodes are connected, and the M second pixel electrodes are suspended. When the ultrasonic fingerprint recognition module is in receiving mode, both the N first pixel electrodes and the M second pixel electrodes are connected. Implementing this application embodiment can improve the accuracy of fingerprint information recognition.

Description

Technical Field

[0001] This application relates to the field of terminal equipment technology, and in particular to an ultrasonic fingerprint recognition module, system and electronic device. Background Technology

[0002] As user demand for full-screen technology continues to grow, under-display fingerprint recognition technology is also constantly evolving. Currently, under-display fingerprint recognition technology is mainly divided into two types: optical fingerprint recognition and ultrasonic fingerprint recognition. The ultrasonic fingerprint recognition module (also known as an ultrasonic fingerprint module) is placed directly under the screen and uses a piezoelectric layer to transmit and receive ultrasonic waves, thereby acquiring and recognizing fingerprint image information. Compared to optical fingerprint recognition modules, ultrasonic fingerprint recognition modules are better suited to the current trend of decreasing screen transmittance. Furthermore, ultrasonic fingerprint recognition modules are thinner, which is beneficial for the overall structural design of the phone and can also be applied to foldable phones. More importantly, ultrasonic fingerprint recognition is faster and does not suffer from light leakage or glare issues.

[0003] However, current ultrasonic fingerprint recognition modules also have the following problems: One problem is that the ultrasonic waves emitted by current ultrasonic fingerprint recognition modules have insufficient penetration ability, especially when applied to terminals with tempered glass screen protectors. The tempered glass screen protector affects the penetration of ultrasonic waves, resulting in a smaller amount of echo signal reflected back, which prevents the ultrasonic fingerprint recognition module from accurately and effectively recognizing fingerprint information. Another problem is that the ultrasonic fingerprint recognition module is placed close to the bottom of the screen, and the echo signal contains a large amount of signal reflected back from other devices, resulting in a lower original signal-to-noise ratio (SNR) for the fingerprint image, which also prevents the ultrasonic fingerprint recognition module from accurately and effectively recognizing fingerprint information.

[0004] Therefore, improving the accuracy of ultrasonic fingerprint recognition modules in identifying fingerprint information is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] This application provides an ultrasonic fingerprint recognition module, system, and electronic device to improve the accuracy of fingerprint recognition information by the ultrasonic fingerprint recognition module.

[0006] In a first aspect, embodiments of this application provide an ultrasonic fingerprint recognition module, comprising: a common electrode, a piezoelectric layer, and a circuit board stacked together. The circuit board includes a plurality of pixel electrode units arranged in an array near the piezoelectric layer. Each pixel electrode unit corresponds to a pixel, and each pixel electrode unit includes N first pixel electrodes and M second pixel electrodes, where N and M are both integers greater than or equal to 1. One side of the piezoelectric layer is electrically connected to the common electrode, and the other side of the piezoelectric layer is electrically connected to the plurality of pixel electrode units. When the ultrasonic fingerprint recognition module is in transmitting mode, the N first pixel electrodes are in a connected state, and the M second pixel electrodes are in a suspended state. When the ultrasonic fingerprint recognition module is in receiving mode, both the N first pixel electrodes and the M second pixel electrodes are in the connected state.

[0007] In existing technologies, one pixel corresponds to only one pixel electrode, and the connection state of all pixel electrodes is consistent in both ultrasonic transmission and reception modes; that is, all pixel electrodes are in a connected state. This structure of pixel electrodes and the identical connection state lead to insufficient penetration of ultrasonic waves in transmission mode and low original signal-to-noise ratio in the fingerprint image in reception mode. To address this, the ultrasonic fingerprint recognition module provided in this application provides an electrode structure where one pixel corresponds to multiple pixel electrodes. This improves the penetration of ultrasonic waves in transmission mode, increases the original signal-to-noise ratio in the fingerprint image in reception mode, and thus improves the accuracy of fingerprint recognition. For example, the ultrasonic fingerprint recognition module may include: a stacked common electrode, a piezoelectric layer, and a circuit board. The circuit board, near the piezoelectric layer, includes multiple pixel electrode units arranged in an array. Each pixel electrode unit corresponds to one pixel, and each pixel electrode unit includes multiple pixel electrodes, such as N first pixel electrodes and M second pixel electrodes, where N and M are integers greater than or equal to 1. For example, a pixel electrode unit may include one first pixel electrode and one second pixel electrode. Compared to existing technologies where one pixel corresponds to only one pixel electrode, this embodiment allows one pixel to correspond to multiple pixel electrodes, thus improving the accuracy of fingerprint recognition. Furthermore, these pixel electrodes are independent of each other; that is, the connection states of the first and second pixel electrodes in a pixel electrode unit can differ. For example, in the transmitting mode of the ultrasonic fingerprint recognition module, N first pixel electrodes are connected, and M second pixel electrodes are suspended; in the receiving mode, both N first pixel electrodes and M second pixel electrodes are connected. This method, where only a portion of the pixel electrodes (e.g., N first pixel electrodes) in each pixel electrode unit are connected to the ultrasonic wave transmitting circuit in transmitting mode, significantly increases the amplification factor when transmitting ultrasonic waves, compared to all pixel electrodes being connected. This enhances the penetration ability of the ultrasonic waves, making it easier for them to penetrate layers. In receive mode, all pixel electrodes are connected to the circuit for receiving echo signals. In transmit mode, some pixel electrodes are connected, and in receive mode, all pixel electrodes are connected. This can increase the proportion of effective voltage read in receive mode, that is, increase the original signal-to-noise ratio of the fingerprint image in receive mode, thereby improving the accuracy of fingerprint information recognition by the ultrasonic fingerprint recognition module.

[0008] In one possible implementation, in the transmission mode, the N first pixel electrodes are in the connected state via a DC bias connection.

[0009] In this embodiment, when the ultrasonic fingerprint recognition module is in transmitting mode, the N first pixel electrodes in each pixel unit are in a connected state through a DC bias connection. For example, the N first pixel electrodes can be connected to a fixed level, AC ground, etc. The N first pixel electrodes can form an electrostatic field on one side of the piezoelectric layer through the DC bias (where the other side of the piezoelectric layer is provided by a high-frequency AC current from a common electrode), causing the piezoelectric layer to change from a static state to a high-frequency mechanical vibration state in the thickness direction, thereby generating and transmitting ultrasonic waves.

[0010] In one possible implementation, the circuit board further includes a reading module for identifying fingerprint information; in the receiving mode, the N first pixel electrodes and the M second pixel electrodes are in a connected state by connecting to the reading module.

[0011] In this embodiment, the circuit board further includes a reading module, which can be used to identify fingerprint information. After the piezoelectric layer receives the echo signal, a large amount of charge is generated on both sides of the piezoelectric layer based on the echo signal. At this time, the pixel electrodes on one side of the piezoelectric layer (e.g., all the first pixel electrodes and second pixel electrodes in each pixel electrode unit) can transmit the above-mentioned charge when connected to the reading module, so that the reading module can identify fingerprint information based on the high-frequency electrical signal.

[0012] In one possible implementation, the circuit board further includes an electrode control module, which includes one or more switching transistors; each of the switching transistors is connected to one or more of the M second pixel electrodes, and each second pixel electrode corresponds to one switching transistor; when the ultrasonic fingerprint recognition module is in the transmitting mode, the one or more switching transistors are turned off to control all the M second pixel electrodes to be in the floating state; when the ultrasonic fingerprint recognition module is in the receiving mode, the one or more switching transistors are turned on to control all the M second pixel electrodes to be in the connected state.

[0013] This application provides a simple and effective electrode control module. This module can regulate the connection state of the second pixel electrodes in a pixel electrode unit under different modes using one or more switching transistors. Each switching transistor can connect to one or more of the M second pixel electrodes, controlling all the M second pixel electrodes to be in a floating state in transmission mode and in a connected state in reception mode. This method of controlling the connection state of pixel electrodes through switching transistors allows for simpler control of the equivalent capacitance of the piezoelectric layer, thereby improving the penetration capability of ultrasonic waves in transmission mode and increasing the signal-to-noise ratio of fingerprint information in reception mode.

[0014] In one possible implementation, the electrode control module includes M switching transistors, each of which is connected to each of the second pixel electrodes in a one-to-one correspondence.

[0015] In this embodiment, each second pixel electrode corresponds to a separate switch, enabling the electrode control module to more precisely control the connection or disconnection of the second pixel electrode. Furthermore, the independence of each second pixel electrode significantly reduces the risk of low fingerprint recognition accuracy due to device errors, ensuring the success rate of fingerprint recognition by the ultrasonic fingerprint recognition module.

[0016] In one possible implementation, each of the switching transistors includes a control terminal, a first terminal, and a second terminal; wherein the control terminal is used to receive a control signal, the control signal being used to control the corresponding switching transistor to be turned on or off; the first terminal is connected to the second pixel electrode controlled by the switching transistor, and the second terminal is connected to the readout module.

[0017] In this embodiment, each switch includes three terminals: a control terminal, a first terminal, and a second terminal. The switch can receive a control signal through the control terminal to control its on / off state, thereby controlling the connection state of the second pixel electrode by adjusting the switch's on / off state. Furthermore, the type of switch can be selected based on the application scenario.

[0018] In one possible implementation, the circuit substrate is a thin-film field-effect transistor (TFT) circuit substrate, and each of the switching transistors is a TFT; or, the circuit substrate is a metal-oxide-semiconductor (CMOS) circuit substrate, and each of the switching transistors is a CMOS.

[0019] In this application embodiment, an effective circuit board and a corresponding switching transistor type are provided. TFT-type circuit boards correspond to TFT switching transistors, and CMOS-type circuit boards are provided to better suit various application scenarios.

[0020] In one possible implementation, a first gap exists between every two adjacent pixel electrode units in the plurality of pixel electrode units, and a second gap exists between adjacent first pixel electrodes and / or second pixel electrodes in each pixel electrode unit, wherein the first gap is greater than or equal to the second gap.

[0021] In this embodiment, a first gap exists between each pixel electrode unit, and a second gap also exists between the first pixel electrode and the second pixel electrode within each pixel electronic unit. When the first gap is greater than or equal to the second gap, the echo signal can be received more effectively to obtain valid fingerprint information, thereby improving the accuracy of fingerprint recognition.

[0022] Secondly, embodiments of this application provide a fingerprint recognition system, which includes an ultrasonic fingerprint recognition module provided by the first aspect or any possible implementation thereof, the ultrasonic fingerprint recognition module being used to recognize fingerprint information.

[0023] Thirdly, embodiments of this application provide an electronic device, the electronic device including a display screen and an ultrasonic fingerprint recognition module provided by the first aspect or any possible implementation of the first aspect, the electronic device recognizing fingerprint information based on the ultrasonic fingerprint recognition module when it recognizes a touch operation on the display screen.

[0024] It should be understood that the fingerprint recognition system provided in the second aspect of this application and the electronic device provided in the third aspect are consistent with the technical solutions of the first aspect of this application. Their specific contents and beneficial effects can be referred to the ultrasonic fingerprint recognition module provided in the first aspect above, and will not be repeated here. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the background art, the accompanying drawings used in the embodiments of this application or the background art will be described below.

[0026] Figure 1 This is a schematic diagram of the structure of an ultrasonic fingerprint recognition module in the prior art, provided in an embodiment of this application.

[0027] Figure 2 This is a schematic diagram of an application scenario provided in an embodiment of this application.

[0028] Figure 3A This is a schematic diagram of an ultrasonic fingerprint recognition module structure provided in an embodiment of this application.

[0029] Figure 3B These are schematic diagrams of the structures of several pixel electrode units provided in the embodiments of this application.

[0030] Figure 4 This is a schematic diagram of the state of a pixel electrode unit in a transmitting mode and a receiving mode provided in an embodiment of this application.

[0031] Figure 5 This is a circuit diagram of an ultrasonic fingerprint recognition module in transmission mode, provided in an embodiment of this application.

[0032] Figure 6 This is a circuit diagram of an ultrasonic fingerprint recognition module in receiving mode, provided in an embodiment of this application.

[0033] Figure 7 This is a circuit diagram of an electrode control module provided in an embodiment of this application.

[0034] Figure 8 This is a timing diagram corresponding to an ultrasonic fingerprint recognition module provided in an embodiment of this application.

[0035] Figure 9 This is a circuit diagram of another electrode control module provided in an embodiment of this application.

[0036] Figure 10 These are several fingerprint recognition systems provided in the embodiments of this application. Detailed Implementation

[0037] The embodiments of this application will now be described with reference to the accompanying drawings.

[0038] The terms "first," "second," "third," and "fourth," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0039] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0040] For ease of description, embodiments of this application may use spatial relation terms such as "below," "below," "lower than," "below," "above," "upper," etc., to describe the relationship between an element or feature shown in the accompanying drawings and other elements or features. It will be understood that these spatial relation terms are intended to include orientations of the device in use or operation other than those depicted in the drawings. For example, if the device in the drawings is flipped, the orientation of an element described as "below," "below," or "below" other elements or features will change to "above" said other elements or features. Thus, the exemplary terms "below" and "below" can encompass both up and down directions. The device may also have other orientations (rotated 90 degrees or in other orientations), and therefore the spatial relation descriptors used herein should be interpreted accordingly. Furthermore, it will be understood that when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or there may be one or more layers in between.

[0041] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0042] As used in this specification, the terms "component," "module," "system," etc., are used to refer to computer-related entities, hardware, firmware, combinations of hardware and software, software, or software in execution. For example, a component can be, but is not limited to, a process running on a processor, a processor, an object, an executable file, an execution thread, a program, and / or a computer. As illustrated, applications running on computing devices and computing devices can both be components. One or more components may reside in a process and / or an execution thread, and components may be located on a single computer and / or distributed among two or more computers. Furthermore, these components can be executed from various computer-readable media on which various data structures are stored. Components can communicate, for example, via local and / or remote processes based on signals having one or more data packets (e.g., data from two components interacting with another component between a local system, a distributed system, and / or a network, such as the Internet interacting with other systems via signals).

[0043] First, in order to facilitate understanding of the embodiments of this application, the technical problems to be solved by the embodiments of this application are analyzed in detail below.

[0044] As user demand for full-screen technology continues to grow, under-display fingerprint recognition technology is also constantly evolving. Currently, under-display fingerprint recognition technology is mainly divided into two types: optical fingerprint recognition and ultrasonic fingerprint recognition. The ultrasonic fingerprint recognition module (also known as an ultrasonic fingerprint module) is placed directly under the screen and uses a piezoelectric layer to transmit and receive ultrasonic waves, thereby acquiring and recognizing fingerprint image information. Compared to optical fingerprint recognition modules, ultrasonic fingerprint recognition modules are better suited to the current trend of decreasing screen transmittance. Furthermore, ultrasonic fingerprint recognition modules are thinner, which is beneficial for the overall structural design of the phone and can also be applied to foldable phones. More importantly, ultrasonic fingerprint recognition is faster and does not suffer from light leakage or glare issues.

[0045] Please refer to the attached document. Figure 1 , Figure 1 This is a schematic diagram of the structure of an ultrasonic fingerprint recognition module in the prior art, provided in an embodiment of this application.

[0046] like Figure 1 The image shows an existing ultrasonic fingerprint recognition module solution and its corresponding pixel circuit electrode solution. Figure 1As shown in (1), the ultrasonic fingerprint module is bonded to the underside of the target area of ​​the display screen (e.g., an organic light-emitting diode (OLED) display screen) via an adhesive layer. The target area is the region in the display screen used for fingerprint recognition. The ultrasonic fingerprint recognition module includes a circuit board, a piezoelectric layer, and a common electrode layer (e.g., an Ag electrode). The circuit board may include pixel circuits and pixel electrodes on the surface of the board. These circuits can be thin-film transistor (TFT) circuits or complementary metal-oxide-semiconductor (CMOS) circuits. The piezoelectric layer is a copolymer organic composite material with polyvinylidene fluoride (PVDF) as the core material. Taking a TFT substrate as an example (i.e., the pixel circuit is a TFT circuit), for instance... Figure 1 As shown in (2), this is a magnified side view of a portion of the pixel electrode, which is located below the TFT circuit and connected to the piezoelectric layer. Figure 1 As shown in (3), in some embodiments, the pixel electrodes are arranged in an array on the piezoelectric layer. The pixel electrodes on the TFT circuit can be indium tin oxide (ITO) electrodes, and the gap between adjacent pixel ITO electrodes is about 5 μm.

[0047] However, as mentioned above Figure 1 The ultrasonic fingerprint recognition module shown also has the following problems:

[0048] The current ultrasonic fingerprint recognition module has insufficient penetration capability of the ultrasonic waves it emits, especially when applied to terminal devices with tempered glass screen protectors or when the screen is too thick. The thickness of the screen or the tempered glass screen protector affects the penetration of the ultrasonic waves, which reduces the amount of echo signal reflected back. Consequently, the ultrasonic fingerprint recognition module cannot effectively recognize fingerprint information.

[0049] In addition, since the ultrasonic fingerprint recognition module is placed close to the bottom of the screen, the echo signal will contain a large number of signals reflected back from other devices, resulting in a low original signal-to-noise ratio (SNR) for the fingerprint image. This also causes the ultrasonic fingerprint recognition module to be unable to accurately identify fingerprint information.

[0050] To address this, this application provides an ultrasonic fingerprint recognition module. When the transmittance of the display screen gradually decreases, or when a cover plate is placed over the display screen, the module controls the state of the pixel electrodes in different modes. This allows for a reduction in the equivalent capacitance of the piezoelectric layer in the transmitting mode, while maintaining the same equivalent capacitance in the receiving mode. This improves the overall efficiency of the conversion path between electrical and acoustic signals, thereby increasing the amount of reflected echo signal and enhancing the original signal-to-noise ratio of the fingerprint image for accurate and effective fingerprint identification. For example, the circuit board includes multiple pixel electrode units arranged in an array near the piezoelectric layer. Each pixel electrode unit includes N first pixel electrodes and M second pixel electrodes, where N and M are integers greater than or equal to 1. In this embodiment, one side of the piezoelectric layer is electrically connected to the common electrode, and the other side of the piezoelectric layer is electrically connected to the plurality of pixel electrode units. When the ultrasonic fingerprint recognition module is in transmitting mode, the N first pixel electrodes are in a connected state, and the M second pixel electrodes are in a suspended state. When the ultrasonic fingerprint recognition module is in receiving mode, both the N first pixel electrodes and the M second pixel electrodes are in the connected state. Further specific implementations of this application can be found in the following related embodiments, which will not be repeated here.

[0051] Secondly, based on the technical problems mentioned above, and in order to facilitate understanding of the embodiments of this application, the following describes one of the ultrasonic fingerprint recognition modules on which the embodiments of this application are based.

[0052] This application provides an ultrasonic fingerprint recognition module, comprising: a common electrode, a piezoelectric layer, and a circuit board stacked together. The circuit board includes a plurality of pixel electrode units arranged in an array near the piezoelectric layer. Each pixel electrode unit includes N first pixel electrodes and M second pixel electrodes, where N and M are both integers greater than or equal to 1. One side of the piezoelectric layer is electrically connected to the common electrode, and the other side of the piezoelectric layer is electrically connected to the plurality of pixel electrode units. When the ultrasonic fingerprint recognition module is in transmitting mode, the N first pixel electrodes are in a connected state, and the M second pixel electrodes are in a suspended state; when the ultrasonic fingerprint recognition module is in receiving mode, both the N first pixel electrodes and the M second pixel electrodes are in the connected state.

[0053] Please refer to the attached document. Figure 2 , Figure 2 This is a schematic diagram illustrating an application scenario provided by an embodiment of this application. The ultrasonic fingerprint recognition module can be applied to electronic devices, allowing the devices to unlock themselves using fingerprint recognition. For example... Figure 2 As shown, the electronic device may include a display screen 100, on which an ultrasonic fingerprint recognition module 10 may be attached below a target area. The ultrasonic fingerprint recognition module 10 may be slightly larger than or equal in size to the target area and is used to send ultrasonic waves to identify the user's fingerprint information.

[0054] It should be noted that this application does not impose specific limitations on the material of the display screen 100. For example, the display screen can be a quantum dot light emitting diode (QLED) display device, or an active-matrix organic light emitting diode (AMOLED) display device, etc.

[0055] It should also be noted that, in addition to the display screen, the ultrasonic fingerprint recognition module in this application embodiment can also be disposed inside or under the cover plate, which can be a glass cover plate or a metal cover plate. This application embodiment does not specifically limit the material of the cover plate.

[0056] It should also be noted that the ultrasonic fingerprint recognition module in this application embodiment can also perform fingerprint recognition directly without being encapsulated or covered. For example, when there is no display screen or cover to encapsulate or cover the ultrasonic fingerprint recognition module, that is, when the ultrasonic fingerprint recognition module is disposed on the substrate and directly exposed to the user's finger, the ultrasonic fingerprint recognition module can perform fingerprint recognition.

[0057] Furthermore, the ultrasonic fingerprint recognition module 10 provided in this application embodiment can also be applied to various scenarios that use ultrasonic waves to recognize palm prints or even foot prints, such as using the under-screen ultrasonic fingerprint recognition module 10 in a time clock to recognize palm prints to complete time clocking in, etc. This application embodiment does not specifically limit this.

[0058] Furthermore, this application embodiment uses an example where N=1, M=1, and the ultrasonic fingerprint recognition module is disposed below the display screen to exemplarily describe the above-mentioned ultrasonic fingerprint recognition module 10. Please refer to the appendix. Figure 3A , Figure 3A This is a schematic diagram of an ultrasonic fingerprint recognition module structure provided in an embodiment of this application.

[0059] like Figure 3AAs shown in Figure (1), the ultrasonic fingerprint recognition module 10 is attached to the underside of the target area in the display screen 100 via an adhesive layer. The ultrasonic fingerprint recognition module 10 includes a common electrode 101, a piezoelectric layer 102, and a circuit board 103 stacked together. The circuit board 103 can support the common electrode 101 and the piezoelectric layer 102 and is fixed to the underside of the display screen 100 via the adhesive layer. The circuit board 103 includes a plurality of pixel electrode units 1031 arranged in an array on the side near the piezoelectric layer 102. Each pixel electrode unit 1031 includes N=1 first pixel electrodes 201 and M=1 second pixel electrodes 202. In some embodiments, the ultrasonic fingerprint recognition module 10 may also include a driving circuit 104.

[0060] Among them, such as Figure 3A As shown in Figure (2), one side of the piezoelectric layer 102 is electrically connected to the common electrode 101, and the other side of the piezoelectric layer 102 is electrically connected to the plurality of pixel electrode units 1031. In other embodiments, the plurality of pixel electrode units may also be embedded inside the circuit board 103, which is used to support and insulate the direct electrical connection between the plurality of pixel electrode units.

[0061] like Figure 3A As shown in Figure (3), the piezoelectric layer 102 includes a plurality of pixel electrode units 1031 arranged in a matrix on the side near the circuit substrate 103. Each pixel electrode unit 1031 includes a first pixel electrode 201 and a second pixel electrode 202. The first pixel electrode 201 and the second pixel electrode 202 may be made of indium tin oxide (ITO). This application embodiment does not specifically limit the material of the pixel electrodes.

[0062] Understandably, as mentioned above Figure 3A As shown in (3), one pixel electrode unit corresponds to one pixel. Each pixel electrode unit is a repeating unit, that is, the connection relationship and structure of each pixel electrode unit are consistent. Multiple pixel electrode units can be arranged in an array on one side of the piezoelectric layer. There is a gap between each pixel electrode unit in the horizontal or vertical direction. For example, the gap can be 5μm. This application embodiment does not make a specific limitation on this. In addition, it should be noted that the horizontal and vertical directions can be understood as the horizontal or vertical direction along the display screen when the electronic device is in normal use. This application embodiment does not make a specific limitation on this.

[0063] In other embodiments, multiple pixel electrode units may be arranged at intervals on one side of the piezoelectric layer. That is, the multiple pixel electrode units may be circular, elliptical, rectangular or other geometric shapes, etc. This application does not specifically limit this aspect.

[0064] In some embodiments, the one or more first pixel electrodes and the one or more second pixel electrodes can be understood as being formed by splitting a complete pixel electrode into complementary pixel sub-electrodes. For example: Please refer to the appendix. Figure 3B , Figure 3B These are schematic diagrams illustrating the structures of several pixel electrode units provided in embodiments of this application. For example... Figure 3B As shown in (1), the shapes of the first pixel electrode and the second pixel electrode in each pixel electrode unit can be different, and the first pixel electrode and the second pixel electrode are arranged on one side of the piezoelectric layer with complementary shapes. In other embodiments, the first pixel electrode and the second pixel electrode can also be understood as pixel electrodes with the same material, the same structure, or the same shape, but with different connection states in different modes. For example: as described above Figure 3B As shown in (2), the first pixel electrode and the second pixel electrode in each pixel electrode unit can have the same shape and be arranged on one side of the piezoelectric layer. In addition, besides the above... Figure 3B In addition to the arrangement shown in (2), adjacent first pixel electrodes and / or second pixel electrodes in each pixel electrode unit can also be arranged at intervals. For example: as described above Figure 3B As shown in (3), the first pixel electrode and the second pixel electrode can also be arranged at intervals. In this regard, the embodiments of this application do not impose specific limitations on the shape and arrangement of the pixel electrodes.

[0065] In some embodiments, taking a pixel electrode unit comprising a first pixel electrode and a second pixel electrode as an example, the sum of the dimensions of the first pixel electrode and the second pixel electrode in the horizontal or vertical direction of the pixel electrode unit may be less than or equal to one pixel. In other embodiments, the dimension of each first pixel electrode or each second pixel electrode included in a pixel electrode unit in the horizontal or vertical direction may be less than or equal to one pixel. This application does not impose specific limitations on these aspects.

[0066] It should be noted that the embodiments of this application do not limit the number of first pixel electrodes and second pixel electrodes in each pixel electrode unit, nor the ratio between the number of first pixel electrodes and second pixel electrodes. Their number or ratio can be determined comprehensively based on various factors such as the size of the electronic device, the material of the display screen, or the corresponding application scenario. In other embodiments, the first pixel electrodes and second pixel electrodes can also be switched between each other by the control of a switching transistor. The embodiments of this application do not impose specific limitations on this.

[0067] In some embodiments, there is a first gap between every two adjacent pixel electrode units in the plurality of pixel electrode units, and there is a second gap between adjacent first pixel electrodes and / or second pixel electrodes in each pixel electrode unit, wherein the first gap is greater than or equal to the second gap.

[0068] As mentioned above Figure 3B As shown in (3), there is a first gap between each pixel electrode unit, and there is a second gap between two adjacent pixel electrodes inside each pixel electronic unit, for example: as described above. Figure 3B As shown in (3), a second gap exists between the first pixel electrode and the second pixel electrode. This first gap can be larger than or equal to the second gap to better receive echo signals and obtain valid fingerprint information, thereby improving the accuracy of fingerprint recognition. Furthermore, the size of the first gap in the horizontal direction between multiple pixel electrode units can be different from the size of the first gap in the vertical direction. If multiple second gaps exist within each pixel electrode unit, the sizes of these second gaps can be the same or different; this application does not impose specific limitations on this.

[0069] It should be noted that, in some embodiments, the first and second gaps may be filled with insulating material to maintain independent connections between each pixel electrode. In other embodiments, the insulating material filling the first gap and the insulating material filling the second gap may be the same or different; this application does not specifically limit this aspect.

[0070] Understandable, Figure 3B The pixel electrode unit structures described are merely a few exemplary implementations in the embodiments of this application. The pixel electrode unit structures in the embodiments of this application include, but are not limited to, the above pixel electrode unit structures. For example, each pixel electrode unit includes multiple first pixel electrodes and multiple second pixel electrodes, that is, N and M are both integers greater than 1.

[0071] In the ultrasonic fingerprint recognition module, when it is in transmitting mode, the N first pixel electrodes are connected, and the M second pixel electrodes are suspended. In the ultrasonic fingerprint recognition module, when it is in receiving mode, both the N first pixel electrodes and the M second pixel electrodes are connected. In transmitting mode, the piezoelectric layer can generate and transmit ultrasonic signals based on the high-frequency alternating current connected to the common electrode. In receiving mode, the piezoelectric layer can receive the echo signal reflected from the ultrasonic signal and transmit high-frequency electrical signals to the N first electrodes and the M second electrodes based on the echo signal. These high-frequency electrical signals are used by the ultrasonic fingerprint recognition module to identify fingerprint information.

[0072] The above Figure 3A When the ultrasonic fingerprint recognition module 10 shown is in working condition, this working condition can be divided into a transmitting mode and a receiving mode. For example, based on the above... Figure 3A Please refer to the ultrasonic fingerprint recognition module structure shown below. Figure 4 , Figure 4 This is a schematic diagram of the state of a pixel electrode unit in a transmitting mode and a receiving mode provided in an embodiment of this application.

[0073] The transmitting mode can be used to transmit ultrasonic waves, which can penetrate adhesive layers and the display screen 100. When the ultrasonic fingerprint recognition module is in transmitting mode, the first pixel electrode in each pixel electrode unit is in a connected state, and the second pixel electrode in each pixel electrode unit is in a suspended state. For example: Figure 4 As shown, the first pixel electrode 201 in each pixel electrode unit can be grounded, while the second pixel electrode 202 can be ungrounded. When the first pixel electrode 201 is grounded, a grounded electrostatic field can be formed on one side of the piezoelectric layer for the piezoelectric layer to transmit ultrasonic waves.

[0074] In one possible implementation, in the transmission mode, the N first pixel electrodes are in the connected state via a DC bias connection.

[0075] In this embodiment, when the ultrasonic fingerprint recognition module is in transmitting mode, the N first pixel electrodes in each pixel unit are in a connected state through a DC bias connection. For example, the N first pixel electrodes can be connected to a fixed level, AC ground, etc. The N first pixel electrodes can form an electrostatic field on one side of the piezoelectric layer through the DC bias (where the other side of the piezoelectric layer is provided by a high-frequency AC current from a common electrode), causing the piezoelectric layer to change from a static state to a high-frequency mechanical vibration state in the thickness direction, thereby generating and transmitting ultrasonic waves.

[0076] It should be noted that the first pixel electrode being in a connected state means that it is connected to the circuit for transmitting ultrasonic waves; that is, when the first pixel electrode is in a connected state, it provides an electrostatic field to one side of the piezoelectric layer. The second pixel electrode being in a suspended state means that it is not connected to the circuit for transmitting ultrasonic waves. In this case, with the common electrode connected to a high-frequency alternating current, the piezoelectric layer is subjected to electrostatic high voltages on both sides (one side is the DC bias electric field provided by the first pixel electrode, and the other side is the high-frequency alternating electric field provided by the common electrode). It will change from a static state to a high-frequency mechanical vibration state in the thickness direction, that is, it generates and transmits ultrasonic waves. The ultrasonic vibrations can be transmitted through each layer towards the display screen until they encounter the user's finger pressing on the target area. Some of the ultrasonic waves are reflected, and a small portion continues to propagate forward.

[0077] Therefore, in some other embodiments, the first pixel electrode 201 in each pixel electrode unit can be connected to a fixed level and be in a connected state, while the second pixel electrode 202 can be left unconnected and be in a floating state.

[0078] It should also be noted that the ultrasonic fingerprint recognition module 10 will only be in working condition when the electronic device recognizes the user's pressing signal on the target area.

[0079] Please refer to the attached document. Figure 5 , Figure 5 This is a circuit diagram of an ultrasonic fingerprint recognition module in transmitting mode, provided in an embodiment of this application. Figure 5 As shown, the ultrasonic fingerprint recognition module is in transmission mode. The driving circuit 104 of the ultrasonic fingerprint recognition module 10 also includes a driving chip and a board-level resonant circuit. Among them, as... Figure 5 As shown in Figure (1), in the transmission mode, the N first pixel electrodes 201 in each pixel electrode unit 1031 are connected to AC ground through the output of the driver chip and the internal logic of the circuit board 103. In addition, the driver chip can also output an AC pulse or sinusoidal voltage (e.g., ~30V) to the board-level resonant circuit, which can output an AC signal with a significantly increased voltage value (e.g., ~100V) to the common electrode 101 based on the LC resonance principle. At this time, the pixel electrode unit on one side of the piezoelectric layer 102 is connected to AC ground, and the other side is the common electrode 101, forming an AC electric field, which causes the piezoelectric layer to vibrate (i.e., generate ultrasonic waves).

[0080] like Figure 5 As shown in Figure (2), this is a schematic diagram of the transmission circuit structure in the transmission mode. The driver chip internally drives two switching transistors using two sets of clock signals with opposite phases, enabling the two transistors to be turned on or off complementaryly in a time-division manner. The output signal of the driver chip is related to the inductor L, path resistance R, and equivalent capacitance C of the piezoelectric layer in the board-level resonant circuit during the transmission mode. TX Series connection. As described above, the final ultrasonic center operating frequency generated by the ultrasonic fingerprint recognition module 10 is the resonant frequency of the LC Boost resonant circuit. Specifically, the resonant frequency of this LC Boost resonant circuit is...

[0081] It should be noted that the equivalent capacitance C of this piezoelectric layer in the transmission mode is... TX This is related to the electrodes connected to both sides of the piezoelectric layer. Specifically, with the common electrode remaining unchanged, the equivalent capacitance C of the piezoelectric layer in transmission mode... TXThe capacitance C varies depending on the number of first pixel electrodes or the ratio of the number of first pixel electrodes to the number of second pixel electrodes in each pixel electrode unit on one side of the piezoelectric layer. For example, when the ultrasonic fingerprint recognition module is in transmission mode, given a fixed number of pixel electrodes in each pixel electrode unit, the more pixel electrodes (i.e., first pixel electrodes) on one side of the piezoelectric layer are in a connected state, the greater the equivalent capacitance C of the piezoelectric layer in transmission mode. TX The larger the number of pixel electrodes (i.e., second pixel electrodes) that are suspended on one side of the piezoelectric layer, the greater the equivalent capacitance C of the piezoelectric layer in transmission mode. TX The smaller the capacitance, the lower the capacitance. It is understandable that the equivalent capacitance C of this piezoelectric layer in transmission mode is... TX It is positively correlated with the area of ​​the pixel electrodes that are connected on both sides of the piezoelectric layer.

[0082] For example, with a fixed common electrode, the more pixel electrodes on one side of the piezoelectric layer are in a connected state, the larger the electrode area of ​​the connected circuit, and consequently, the greater the equivalent capacitance C of the piezoelectric layer in the transmission mode. TX The smaller the number of pixel electrodes in a connected state on one side of the piezoelectric layer, the smaller the electrode area of ​​the connected circuit, and consequently the larger the equivalent capacitance C corresponding to the piezoelectric layer in the transmission mode. TX The smaller the value, the better. Therefore, in some embodiments, the ultrasonic fingerprint recognition module 10 can control the equivalent capacitance C of the piezoelectric layer in the transmission mode by controlling the number of pixel electrodes in the connected state. TX Size.

[0083] Furthermore, in order for the ultrasonic fingerprint recognition module to better identify user fingerprint information based on the echo signal reflected from the ultrasonic waves, the center operating frequency of the transmitted ultrasonic waves in this embodiment needs to be within the target resonant frequency range. For example, the target resonant frequency can be set to 5MHz-20MHz. This is based on the resonant frequency f = f0 and the equivalent capacitance C in the transmission mode. TX Then the inductance L in the plate-level resonant circuit should satisfy the following formula: Here, f0 is a pre-set target resonant frequency, which can be used by the ultrasonic fingerprint recognition module to better identify user fingerprint information based on the echo signal reflected back by ultrasonic waves.

[0084] It should also be noted that for the LC Boost resonant circuit in transmit mode, if the power supply voltage of the driver chip is Vin and the output voltage across the piezoelectric layer is Vout, then the voltage amplification factor in transmit mode is:

[0085] Therefore, the amplification factor of the driving voltage of the ultrasonic fingerprint recognition module in transmission mode is strongly correlated with the LC circuit path resistance and the equivalent capacitance corresponding to the piezoelectric layer. Specifically, when the path resistance is fixed, C... TX The smaller the value, that is, the fewer the number of pixel electrodes in the connected state in each pixel electrode unit on one side of the piezoelectric layer, the larger the driving voltage amplification factor, and the greater the vibration amplitude of the corresponding piezoelectric layer, which is more conducive to the penetration of ultrasonic waves.

[0086] When the ultrasonic fingerprint recognition module is in receiving mode, it can receive the echo signal reflected back after the ultrasonic wave transmitted in transmitting mode encounters the user's finger (e.g., the ridge or base of the finger). At this time, all N first pixel electrodes and M second pixel electrodes in each pixel electrode unit are in the connected state.

[0087] It should be noted that "both the first and second pixel electrodes are in a connected state" means that both the first and second pixel electrodes are connected to circuits for receiving and reading echo signals. When an echo signal is received, the reflected ultrasonic wave echo signal passes through the various dielectric layers and reaches the piezoelectric layer. This causes the piezoelectric layer, which was nearly stationary in receiving mode, to be driven by the reflected echo signal and re-enter a high-frequency vibration state. The piezoelectric layer then converts this high-frequency vibration into a high-frequency electrical signal (such as a pulse signal or a sine wave signal). This high-frequency electrical signal can be received by the connected pixel electrodes (such as the first and second pixel electrodes) in the pixel electrode unit located on one side of the piezoelectric layer and transmitted to the relevant circuits for recognizing the echo signal. Finally, the fingerprint information corresponding to the echo signal is obtained. For example, an ultrasonic fingerprint image.

[0088] Understandably, after transmitting the ultrasonic waves, the ultrasonic fingerprint recognition module will switch from transmitting mode to receiving mode. At this time, a high-frequency electric field cannot be formed on both sides of the piezoelectric layer. Therefore, the high-frequency mechanical vibration of the piezoelectric layer will gradually stop due to damping and return to a static state.

[0089] In some embodiments, the circuit board further includes a reading module for identifying fingerprint information; in the receiving mode, the N first pixel electrodes and the M second pixel electrodes are in a connected state by connecting to the reading module.

[0090] In this embodiment, the circuit board further includes a reading module, which can be used to identify fingerprint information. After the piezoelectric layer receives the echo signal, a large amount of charge is generated on both sides of the piezoelectric layer based on the echo signal. At this time, the pixel electrodes on one side of the piezoelectric layer (e.g., all the first pixel electrodes and second pixel electrodes in each pixel electrode unit) can transmit the above-mentioned charge when connected to the reading module, so that the reading module can identify fingerprint information based on the high-frequency electrical signal.

[0091] As mentioned above Figure 4 As shown, when the ultrasonic fingerprint recognition module is in receiving mode, the first pixel electrode 201 and the second pixel electrode 202 in each pixel electrode unit 1031 can be connected to a reading module for reading electrical signals. That is, the reading module can read fingerprint information based on high-frequency electrical signals. The high-frequency electrical signals are transmitted by the first pixel electrode and the second pixel electrode, and the piezoelectric layer generates high-frequency electrical signals based on echo signals.

[0092] It is understandable that this reading module can be integrated not only into the circuit board, but also into the aforementioned... Figure 5 The driver chip shown is not specifically limited in this respect in the embodiments of this application.

[0093] Please refer to the attached document. Figure 6 , Figure 6 This is a circuit diagram of an ultrasonic fingerprint recognition module in receiving mode, provided in an embodiment of this application. Figure 6 As shown in Figure (1), in receive mode, the pixel electrode unit 1031 is connected to the readout module. Figure 6 As shown in (2), the echo signal of the reflected echo is converted into a high-frequency electrical signal through a piezoelectric layer, for example, it can be represented as V RX Voltage, V for each pixel electrode unit RX The equivalent capacitance C of the piezoelectric layer in receiving mode RX And the voltage divider of the parasitic capacitance C0 corresponding to the pixel electrode unit, where V RX_eff The voltage is the effective voltage that the subsequent reading module can read. Therefore, the ratio between the ultrasonic echo voltage and the effective reading voltage during the ultrasonic reading stage is as follows: Therefore, the higher the ratio of ultrasonic echo voltage to effective reading voltage during the ultrasonic reading stage, the higher the original signal-to-noise ratio corresponding to the fingerprint information.

[0094] It should be noted that when the ultrasonic fingerprint recognition module is in receiving mode, given a fixed number of pixel electrodes in the pixel electrode unit, the more pixel electrodes (i.e., the first pixel electrode and the second pixel electrode) are in a connected state on one side of the piezoelectric layer, the greater the equivalent capacitance C of the piezoelectric layer in receiving mode.TX The larger the number of pixel electrodes with one side of the piezoelectric layer in a suspended state, the greater the equivalent capacitance C of the piezoelectric layer in receiving mode. TX The smaller the capacitance, the lower the capacitance. It is understandable that the equivalent capacitance C of this piezoelectric layer in receive mode is... TX The area of ​​the pixel electrodes connected on both sides of the piezoelectric layer is also positively correlated. That is, the more pixel electrodes connected on one side of the piezoelectric layer, the larger the electrode area connected to the receiving circuit, and consequently, the larger the equivalent capacitance C of the piezoelectric layer in receiving mode. TX The larger it is.

[0095] Based on the above analysis, in the receiving mode, when the parasitic capacitance C0 corresponding to the pixel electrode unit is 0, the equivalent capacitance C of the piezoelectric layer in the receiving mode is... RX The larger the capacitance, that is, the more pixel electrodes (i.e., the first pixel electrode and the second pixel electrode) are in a connected state on one side of the piezoelectric layer, the higher the reading efficiency in the receiving mode, and the higher the original signal-to-noise ratio of the corresponding fingerprint information. Here, the fingerprint information can be understood as fingerprint image information.

[0096] In summary, in this embodiment, to improve system efficiency, when the ultrasonic fingerprint recognition module is in transmitting mode, the N first pixel electrodes are in a connected state, and the M second pixel electrodes are in a suspended state; that is, only a portion of the pixel electrodes in each pixel electrode unit are in a connected state. When the ultrasonic fingerprint recognition module is in receiving mode, both the N first pixel electrodes and the M second pixel electrodes are in the connected state; that is, all pixel electrodes in each pixel electrode unit are in a connected state, or more pixel electrodes in each pixel electrode unit are in a connected state than in transmitting mode. This allows the number of connected pixel electrodes in different modes to make the equivalent capacitance of the piezoelectric layer in transmitting mode smaller than that in receiving mode. This enables the ultrasonic fingerprint recognition module to have an electrode structure where one pixel corresponds to multiple pixel electrodes, improving the penetration capability of ultrasonic waves in transmitting mode and increasing the original signal-to-noise ratio of the fingerprint image in receiving mode, thereby improving the accuracy of fingerprint recognition by the ultrasonic fingerprint recognition module.

[0097] In some embodiments, the circuit board further includes an electrode control module, which includes one or more switching transistors; each switching transistor is connected to one or more of the M second pixel electrodes, and each second pixel electrode corresponds to one switching transistor; when the ultrasonic fingerprint recognition module is in the transmitting mode, the one or more switching transistors are turned off to control all the M second pixel electrodes to be in the floating state; when the ultrasonic fingerprint recognition module is in the receiving mode, the one or more switching transistors are turned on to control all the M second pixel electrodes to be in the connected state.

[0098] This electrode control module can regulate the connection state of the second pixel electrode in the pixel electrode unit under different modes using one or more switching transistors. Each switching transistor can connect to one or more of the M second pixel electrodes, controlling all the M second pixel electrodes to be in a floating state in transmit mode and in a connected state in receive mode. Please refer to the appendix. Figure 7 , Figure 7 This is a circuit diagram of an electrode control module provided in an embodiment of this application. Taking the receiving mode as an example, the electrode control module includes one or more switching transistors, such as... Figure 7 As shown in Figure (1), a switching transistor M1 can control a second pixel electrode 202; as Figure 7 As shown in (2), a switch M1 can control two second pixel electrodes 202. The switch M1 can control the corresponding second pixel electrode to be in a floating state in the transmitting mode and in a connected state in the receiving mode.

[0099] In some embodiments, each of the switching transistors includes a control terminal, a first terminal, and a second terminal; wherein the control terminal is used to receive a control signal, the control signal being used to control the corresponding switching transistor to turn on or off; the first terminal is connected to the second pixel electrode controlled by the switching transistor, and the second terminal is connected to the readout module. As described above. Figure 7 As shown in Figure (3), each switch M1 includes three terminals: a control terminal, a first terminal, and a second terminal. The switch can receive a control signal through the control terminal to control its on / off state, thereby controlling the connection state of the second pixel electrode. Furthermore, the type of switch can be determined based on the application scenario. For example, the switch can be either an N-type or a P-type switch. For instance, when the switch is an N-type switch, the control terminal can be the gate, the first terminal can be the drain, and the second terminal can be the source.

[0100] Please refer to the attached document. Figure 8, Figure 8 This is a timing diagram corresponding to an ultrasonic fingerprint recognition module provided in an embodiment of this application. For example... Figure 8 As shown, the control signal is low in transmission mode (i.e., when the piezoelectric layer is subjected to high-frequency alternating current), where the switch is off, thereby controlling the corresponding second pixel electrode to be in a floating state; the control signal is high in reception mode, where the switch is on, thereby controlling the corresponding second pixel electrode to be in a connected state. Additionally, as described above... Figure 8 As shown, after entering receive mode, the read module can start working and perform fingerprint recognition on the received high-frequency electrical signal.

[0101] In other embodiments, the electrode control module includes M switching transistors, each of which is connected to each of the second pixel electrodes in a one-to-one correspondence.

[0102] Please refer to the attached document. Figure 9 , Figure 9 This is a circuit diagram of another electrode control module provided in an embodiment of this application, as shown below. Figure 9 As shown in (1), each second pixel electrode corresponds to a separate switching transistor, allowing the electrode control module to more accurately control the connection or suspension of the second pixel electrode. Furthermore, as... Figure 9 As shown in (2), each second pixel electrode is independently controlled by different switching transistors, which greatly reduces the risk of low fingerprint recognition accuracy caused by device errors and ensures the success rate of fingerprint recognition by the ultrasonic fingerprint recognition module.

[0103] In other embodiments, the substrate further includes an electrode control module, which includes one or more switching transistors; each switching transistor is connected to one or more pixel electrodes. The electrode control module can adjust the number or ratio of first pixel electrodes and second pixel electrodes in each pixel electrode unit. For example, each first pixel electrode or each second pixel electrode can correspond to one switching transistor. The electrode control module can control the connection state of the corresponding pixel electrodes through the switching transistors, wherein a pixel electrode in a connected state in transmission mode can be understood as a first pixel electrode, and a pixel electrode in a floating state in transmission mode can be understood as a second pixel electrode. The first pixel electrode and the second pixel electrode can be switched between each other by the control of the switching transistors. For example, when the received echo signal is weak, the electrode control module can control the conduction or de-conduction of different switching transistors to appropriately reduce the number of first pixel electrodes and increase the number of second pixel electrodes. This application does not impose specific limitations on this aspect.

[0104] In some embodiments, the circuit substrate is a thin-film field-effect transistor (TFT) circuit substrate, and each of the switching transistors is a TFT; or, the circuit substrate is a metal-oxide-semiconductor (CMOS) circuit substrate, and each of the switching transistors is a CMOS. It is understood that when the circuit substrate is a TFT circuit substrate, one or more switching transistors in the corresponding electrode control module are also TFTs; and when the circuit substrate is a CMOS circuit substrate, one or more switching transistors in the corresponding electrode control module are also CMOS. It is understood that TFT circuit substrates correspond to TFT switching transistors, and CMOS circuit substrates correspond to CMOS switching transistors, to better suit various application scenarios.

[0105] In summary, the ultrasonic fingerprint recognition module provided in this application, based on an electrode structure where one pixel corresponds to multiple pixel electrodes, can improve the penetration capability of ultrasonic waves in the transmission mode, increase the original signal-to-noise ratio of the fingerprint image in the reception mode, and thus improve the accuracy of fingerprint recognition. The ultrasonic fingerprint recognition module may include: a stacked common electrode, a piezoelectric layer, and a circuit board. For example, the circuit board near the piezoelectric layer includes multiple pixel electrode units arranged in an array, each pixel electrode unit corresponding to one pixel, and each pixel electrode unit includes multiple pixel electrodes, such as N first pixel electrodes and M second pixel electrodes. For example, one pixel electrode unit may include one first pixel electrode and one second pixel electrode. Compared to the prior art where one pixel corresponds to only one pixel electrode, this application embodiment allows one pixel to correspond to multiple pixel electrodes, which can better improve the accuracy of fingerprint recognition. Furthermore, the pixel electrodes are independent of each other; that is, the connection states of the first and second pixel electrodes in the pixel electrode unit can be different. For example, in the transmitting mode of the ultrasonic fingerprint recognition module, N first pixel electrodes are connected, and M second pixel electrodes are suspended; in the receiving mode of the ultrasonic fingerprint recognition module, both N first pixel electrodes and M second pixel electrodes are connected. In transmitting mode, only a portion of the pixel electrodes (e.g., N first pixel electrodes) in each pixel electrode unit are connected to the ultrasonic wave transmitting circuit, which significantly increases the amplification factor when transmitting ultrasonic waves, compared to all pixel electrodes being connected. This enhances the penetration ability of the ultrasonic waves, making it easier for them to penetrate layers. In receiving mode, all pixel electrodes are connected to the circuit for receiving echo signals. This connection of some pixel electrodes in transmitting mode and all pixel electrodes in receiving mode increases the proportion of effective voltage read in receiving mode, i.e., increases the original signal-to-noise ratio of the fingerprint image in receiving mode, thereby improving the accuracy of the ultrasonic fingerprint recognition module in recognizing fingerprint information.

[0106] This application embodiment also provides a fingerprint recognition system, which includes an ultrasonic fingerprint recognition module, and the ultrasonic fingerprint recognition module can be the one described above. Figures 2-9 The ultrasonic fingerprint recognition module involved in the related embodiments shown is illustrated.

[0107] The fingerprint recognition system may also include a cover plate or a display. Please refer to the appendix. Figure 10 , Figure 10 These are several fingerprint recognition systems provided in the embodiments of this application. For example... Figure 10As shown in Figure (1), the fingerprint recognition system may also include a cover plate, which may be a glass cover plate, a metal cover plate, or a plastic cover plate. The ultrasonic fingerprint recognition module can be fixed to the underside of the cover plate through an adhesive layer, and then used to recognize the fingerprint information when a fingerprint recognition operation is detected on the cover plate. Figure 10 As shown in (2), the ultrasonic fingerprint recognition module of the fingerprint recognition system can be exposed directly under the user's finger to be recognized without being covered. At this time, the ultrasonic fingerprint recognition module can be supported by the substrate.

[0108] In addition, it should be noted that the ultrasonic fingerprint recognition module can be embedded in the substrate or located on the substrate. The specific location of the ultrasonic fingerprint recognition module is not specifically limited in the embodiments of this application.

[0109] It should also be noted that the ultrasonic fingerprint recognition module can be fixed to the bottom of the cover plate by an adhesive layer, or it can be located inside the cover plate. This application embodiment does not make specific limitations in this regard.

[0110] This application also provides an electronic device, which includes a display screen and the aforementioned... Figures 2-9 The ultrasonic fingerprint recognition module involved in the related embodiments shown allows the electronic device to identify fingerprint information based on the ultrasonic fingerprint recognition module when a touch operation is detected on the display screen. The ultrasonic fingerprint recognition module can be located inside or under the display screen; this application does not specifically limit its location.

[0111] It should be understood that the fingerprint recognition system or electronic device provided in the embodiments of this application is similar to the one described above. Figures 2-9 The ultrasonic fingerprint recognition module involved in the related embodiments shown is the same, and its specific content and beneficial effects can be referred to above. Figures 2-9 The ultrasonic fingerprint recognition module involved in the related embodiments shown will not be described in detail here.

[0112] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0113] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0114] In the several embodiments provided in this application, it should be understood that the disclosed apparatus can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of the units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical or other forms.

[0115] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0116] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0117] If the integrated units described above are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which can be a personal computer, server, or network device, specifically a processor in the computer device) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium may include various media capable of storing program code, such as a USB flash drive, portable hard drive, magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM).

[0118] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. An ultrasonic fingerprint recognition module, characterized in that, include: The circuit board comprises a common electrode, a piezoelectric layer, and a circuit substrate stacked together. The circuit substrate includes multiple pixel electrode units arranged in an array near the piezoelectric layer. Each pixel electrode unit corresponds to a pixel, and each pixel electrode unit includes N first pixel electrodes and M second pixel electrodes, where N and M are both integers greater than or equal to 1. One side of the piezoelectric layer is electrically connected to the common electrode, and the other side of the piezoelectric layer is electrically connected to the multiple pixel electrode units. When the ultrasonic fingerprint recognition module is in the transmitting mode, the N first pixel electrodes are in a connected state, and the M second pixel electrodes are in a suspended state; the connected state means that the circuit for transmitting ultrasonic waves is connected, and the suspended state means that the circuit for transmitting ultrasonic waves is not connected. When the ultrasonic fingerprint recognition module is in receiving mode, all N first pixel electrodes and M second pixel electrodes are in the connected state.

2. The module of claim 1, wherein In the transmission mode, the N first pixel electrodes are in the connected state by connecting a DC bias.

3. The module of claim 1, wherein The circuit board also includes a reading module, which is used to identify fingerprint information; In the receiving mode, the N first pixel electrodes and the M second pixel electrodes are in the connected state by connecting to the reading module.

4. The module of claim 3, wherein The circuit board further includes an electrode control module, which includes one or more switching transistors; each of the switching transistors is connected to one or more of the M second pixel electrodes, and each second pixel electrode corresponds to one of the switching transistors. When the ultrasonic fingerprint recognition module is in the transmission mode, the one or more switching transistors are turned off to control all the second pixel electrodes of the M second pixel electrodes to be in the floating state; When the ultrasonic fingerprint recognition module is in the receiving mode, one or more switching transistors are turned on to control all the second pixel electrodes of the M second pixel electrodes to be in the connected state.

5. The module of claim 4, wherein The electrode control module includes M switching transistors, each of which is connected to each of the second pixel electrodes in a one-to-one correspondence.

6. The module of claim 4 or 5, wherein Each of the aforementioned switching transistors includes a control terminal, a first terminal, and a second terminal; The control terminal is used to receive control signals, which are used to control the corresponding switching transistor to turn on or off; the first terminal is connected to the second pixel electrode controlled by the switching transistor, and the second terminal is connected to the reading module.

7. The module according to any one of claims 4-5, characterized in that, The circuit substrate is a thin-film field-effect transistor (TFT) circuit substrate, and each of the switching transistors is a thin-film field-effect transistor (TFT); or... The circuit board is a metal-oxide-semiconductor (CMOS) circuit board, and each of the switching transistors is a metal-oxide-semiconductor (CMOS) transistor.

8. The module according to any one of claims 1-5, characterized in that, There is a first gap between every two adjacent pixel electrode units in the plurality of pixel electrode units, and there is a second gap between adjacent first pixel electrodes and / or second pixel electrodes in each pixel electrode unit, wherein the first gap is greater than or equal to the second gap.

9. A fingerprint recognition system, characterized in that, The fingerprint recognition system includes an ultrasonic fingerprint recognition module as described in any one of claims 1-8, wherein the ultrasonic fingerprint recognition module is used to identify fingerprint information.

10. An electronic device, comprising: The electronic device includes a display screen and an ultrasonic fingerprint recognition module as described in any one of claims 1-8. When the electronic device detects a touch operation performed on the display screen, it identifies fingerprint information based on the ultrasonic fingerprint recognition module.

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