CN117058725A

CN117058725A - Ultrasonic fingerprint identification module, system and electronic equipment

Info

Publication number: CN117058725A
Application number: CN202310816405.1A
Authority: CN
Inventors: 张翠萍; 苏悦; 迟世鹏; 邱赫梓
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2023-07-04
Filing date: 2023-07-04
Publication date: 2023-11-14

Abstract

The embodiment of the application provides an ultrasonic fingerprint identification module, an ultrasonic fingerprint identification system and electronic equipment. Wherein, an ultrasonic fingerprint identification module includes: the piezoelectric display comprises a public electrode, a piezoelectric layer and a circuit substrate which are stacked, wherein one side, close to the piezoelectric layer, of the circuit substrate comprises a plurality of pixel electrode units which are arranged in an array manner, each pixel electrode unit corresponds to one pixel, and each pixel electrode unit comprises N first pixel electrodes and M second pixel electrodes; one side of the piezoelectric layer is electrically connected with the common electrode, and the other side of the piezoelectric layer is electrically connected with the pixel electrode units; under the condition that the ultrasonic fingerprint identification module is in a transmitting mode, N first pixel electrodes are in a communicating state, and M second pixel electrodes are in a suspending state; under the condition that the ultrasonic fingerprint identification module is in a receiving mode, the N first pixel electrodes and the M second pixel electrodes are in a communicating state. By implementing the embodiment of the application, the accuracy of identifying the fingerprint information can be improved.

Description

Ultrasonic fingerprint identification module, system and electronic equipment

Technical Field

The application relates to the technical field of terminal equipment, in particular to an ultrasonic fingerprint identification module, an ultrasonic fingerprint identification system and electronic equipment.

Background

With the continuous development of users' demands for comprehensive screen technologies, the technology of off-screen fingerprint recognition is also continuously developed. The current on-screen fingerprint identification technology is mainly divided into two types: optical fingerprint recognition and ultrasonic fingerprint recognition. The ultrasonic fingerprint recognition module (also called as ultrasonic fingerprint recognition module) clings to the lower part of the screen and can transmit and receive ultrasonic waves by utilizing the piezoelectric layer, so that the acquisition and recognition of fingerprint image information are carried out. Compared with the optical fingerprint recognition module, the ultrasonic fingerprint recognition module is more suitable for the technical development trend that the transmittance of the current screen is continuously reduced, the thickness of the ultrasonic fingerprint recognition module is thinner, the whole structure design of the mobile phone is facilitated, the ultrasonic fingerprint recognition module can be applied to the folding screen mobile phone, more importantly, the ultrasonic fingerprint recognition speed is higher, and no light leakage dazzling public opinion and the like are generated.

However, the current ultrasonic fingerprint recognition module also has the following problems: one problem is that the penetrating power of the ultrasonic wave that current ultrasonic fingerprint identification module sent is not enough, especially when being applied to the terminal of the screen that has toughened glass film, the toughened film can influence the penetration of ultrasonic wave to make the echo signal volume size that ultrasonic wave reflection was back, lead to the unable accurate fingerprint information of effectively discerning of ultrasonic fingerprint identification module. Another problem is that the ultrasonic fingerprint recognition module is tightly attached to the lower portion of the screen, and the echo Signal has a large number of signals reflected by other devices, so that the original Signal-to-noise ratio (SNR) corresponding to the current fingerprint image is small, and therefore the ultrasonic fingerprint recognition module cannot accurately and effectively recognize fingerprint information.

Therefore, how to improve the accuracy of fingerprint information recognition by the ultrasonic fingerprint recognition module is a technical problem to be solved.

Disclosure of Invention

The embodiment of the application provides an ultrasonic fingerprint identification module, an ultrasonic fingerprint identification system and electronic equipment, so as to improve the accuracy of fingerprint information identification of the ultrasonic fingerprint identification module.

In a first aspect, an embodiment of the present application provides an ultrasonic fingerprint identification module, including: the piezoelectric display device comprises a public electrode, a piezoelectric layer and a circuit substrate which are arranged in a stacked manner, wherein one side, close to the piezoelectric layer, of the circuit substrate comprises a plurality of pixel electrode units which are arranged in an array manner, each pixel electrode unit corresponds to one pixel, each pixel electrode unit comprises N first pixel electrodes and M second pixel electrodes, and N and M are integers which are larger than or equal to 1; one side of the piezoelectric layer is electrically connected with the common electrode, and the other side of the piezoelectric layer is electrically connected with the pixel electrode units; under the condition that the ultrasonic fingerprint identification module is in a transmitting mode, the N first pixel electrodes are in a communicating state, and the M second pixel electrodes are in a suspending state; and under the condition that the ultrasonic fingerprint identification module is in a receiving mode, the N first pixel electrodes and the M second pixel electrodes are in the communication state.

In the prior art, one pixel corresponds to only one pixel electrode, and the connection states of all pixel electrodes in an ultrasonic wave transmitting mode and a receiving mode are consistent, namely all pixel electrodes are in a communication state, and the structure and the same connection state of the pixel electrodes can cause insufficient penetrating capacity of ultrasonic waves in the transmitting mode, so that the original signal-to-noise ratio corresponding to a fingerprint image in the receiving mode is smaller. In this regard, the ultrasonic fingerprint recognition module provided in the embodiment of the application is based on the electrode structure of the plurality of pixel electrodes corresponding to one pixel, so that the penetrating capability of ultrasonic waves in a transmission mode can be improved, the original signal-to-noise corresponding to the fingerprint image in a receiving mode is increased, and the accuracy of fingerprint information recognition of the ultrasonic fingerprint recognition module is further improved. Illustratively, the ultrasonic fingerprint recognition module may include: the common electrode, the piezoelectric layer, and the circuit substrate are stacked. The circuit substrate comprises a piezoelectric layer, wherein one side of the circuit substrate, which is close to the piezoelectric layer, comprises a plurality of pixel electrode units which are arranged in an array manner, each pixel electrode unit corresponds to one pixel, each pixel electrode unit comprises a plurality of pixel electrodes, for example, N first pixel electrodes and M second pixel electrodes, and N and M are integers which are larger than or equal to 1. For example: a pixel electrode unit may include a first pixel electrode and a second pixel electrode. Compared with the condition that one pixel corresponds to only one pixel electrode in the prior art, one pixel can correspond to a plurality of pixel electrodes, and accuracy of identifying fingerprint information can be improved better. In addition, the pixel electrodes are independent of each other, that is, the connection states of the first pixel electrode and the second pixel electrode in the pixel electrode unit may be different, for example: under the condition that the ultrasonic fingerprint identification module is in a transmitting mode, N first pixel electrodes are in a communicating state, and M second pixel electrodes are in a suspending state; under the condition that the ultrasonic fingerprint identification module is in a receiving mode, the N first pixel electrodes and the M second pixel electrodes are in a communicating state. In the transmitting mode, only part of pixel electrodes (such as N first pixel electrodes) in each pixel electrode unit are connected to a circuit for transmitting ultrasonic waves, and compared with all the pixel electrodes in a communicating state, the transmitting mode can greatly improve the corresponding amplification coefficient when transmitting the ultrasonic waves, so that the penetrating capacity of the ultrasonic waves is improved, and the ultrasonic waves are easier to penetrate through each layer. All pixel electrodes are connected into a circuit for receiving echo signals in a receiving mode, and part of pixel electrodes are communicated in the transmitting mode and all pixel electrodes are communicated in the receiving mode, so that the proportion of effective voltage reading in the receiving mode can be improved, namely, the original signal-to-noise corresponding to a fingerprint image in the receiving mode is increased, and the accuracy of fingerprint information identification of an ultrasonic fingerprint identification module is improved better.

In one possible implementation, in the transmission mode, the N first pixel electrodes are in the connected state by a connected dc bias.

In the embodiment of the application, when the ultrasonic fingerprint identification module is in a transmitting mode, N first pixel electrodes in each pixel unit are in the communication state through connecting direct current bias. For example: the N first pixel electrodes may be connected to a fixed level, an ac ground, or the like, and may form an electrostatic field on one side of the piezoelectric layer (wherein the other side of the piezoelectric layer is a high-frequency ac power supplied from the common electrode) by dc bias, so that the piezoelectric layer is converted from a stationary state to a high-frequency mechanical vibration state in the thickness direction, thereby generating and transmitting ultrasonic waves.

In one possible implementation manner, the circuit substrate further comprises a reading module, wherein the reading module is used for identifying fingerprint information; in the receiving mode, the N first pixel electrodes and the M second pixel electrodes are in the connected state by being connected to the reading module.

In the embodiment of the application, the circuit substrate further comprises a reading module, and the reading module can be used for identifying fingerprint information. After the piezoelectric layer receives the echo signal, a large amount of charges are generated on two sides of the piezoelectric layer based on the echo signal, and at this time, pixel electrodes (such as all first pixel electrodes and all second pixel electrodes in each pixel electrode unit) on one side of the piezoelectric layer can transmit the charges under the condition of being communicated with the reading module, so that the reading module can identify fingerprint information based on the high-frequency electric signal.

In one possible implementation, the circuit substrate further includes an electrode control module including one or more switching tubes; each switching tube is correspondingly connected with one or more second pixel electrodes in the M second pixel electrodes, and each second pixel electrode corresponds to one switching tube; when the ultrasonic fingerprint identification module is in the sending mode, the one or more switch tubes are turned off so as to control all second pixel electrodes of the M second pixel electrodes to be in the suspended state; and under the condition that the ultrasonic fingerprint identification module is in the receiving mode, the one or more switch tubes are conducted so as to control all second pixel electrodes of the M second pixel electrodes to be in the communication state.

In the embodiment of the application, a simple and effective electrode control module is provided, and the electrode control module can regulate and control the connection state of the second pixel electrode in the pixel electrode unit under different modes through one or more switch tubes. Each switching tube can be connected with one or more second pixel electrodes in the M second pixel electrodes so as to control all the second pixel electrodes in the M second pixel electrodes to be in a suspended state in a sending mode and to be in a communicating state in a receiving mode. The electrode control module can control the size of the equivalent capacitance corresponding to the piezoelectric layer more simply by controlling the connection state of the pixel electrode through the switch tube, so that the penetrating capacity of ultrasonic waves in a sending mode is improved, and the signal-to-noise ratio of fingerprint information in a receiving mode is increased.

In one possible implementation manner, the electrode control module includes M switching tubes, and each switching tube is connected to each second pixel electrode in a one-to-one correspondence.

In the embodiment of the application, each second pixel electrode is independently corresponding to one switching tube, so that the electrode control module can more finely realize the control of the connection or suspension of the second pixel electrodes. Moreover, each second pixel electrode is mutually independent, so that the risk of low fingerprint identification accuracy caused by device errors is greatly reduced, and the success rate of fingerprint identification by the ultrasonic fingerprint identification module is ensured.

In one possible implementation, each of the switching tubes includes a control end, a first end, and a second end; the control end is used for receiving a control signal, and the control signal is used for controlling the on or off of the corresponding switching tube; the first end is connected with a second pixel electrode controlled by the switch tube, and the second end is connected with the reading module.

In the embodiment of the application, each switching tube comprises three ends, namely: a control end, a first end and a second end. The switching tube can receive a control signal through the control end and control the on or off of the switching tube, so that the connection state of the second pixel electrode is controlled by adjusting the on or off of the switching tube. In addition, the selection of the type of the switching tube can be determined according to the application scene.

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 thin film field effect transistor TFT; or the circuit substrate is a metal oxide transistor (CMOS) circuit substrate, and each switching tube is a metal oxide transistor (CMOS).

In an embodiment of the application, an effective circuit substrate and a corresponding switching tube type are provided. The TFT type circuit substrate corresponds to the TFT switch tube and the CMOS type circuit substrate so as to be better suitable for various application scenes.

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

In the embodiment of the application, 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 inside each pixel electronic unit. Under the condition that the first gap is larger than or equal to the second gap, the echo signals can be better received to obtain effective fingerprint information, and the accuracy of fingerprint identification is improved.

In a second aspect, an embodiment of the present application provides a fingerprint identification system, where the fingerprint identification system includes an ultrasonic fingerprint identification module provided in the first aspect or any one of possible implementation manners of the first aspect, where the ultrasonic fingerprint identification module is used to identify fingerprint information.

In a third aspect, an embodiment of the present application provides an electronic device, where the electronic device includes a display screen and an ultrasonic fingerprint recognition module provided by the first aspect or any one of the possible implementation manners of the first aspect, where the electronic device recognizes fingerprint information based on the ultrasonic fingerprint recognition module when recognizing a touch operation acting on the display screen.

It should be understood that, the fingerprint recognition system provided in the second aspect of the present application, and the electronic device provided in the third aspect of the present application are consistent with the technical solutions of the first aspect of the present application, and specific content and beneficial effects thereof may refer to the ultrasonic fingerprint recognition module provided in the first aspect, which is not described herein.

Drawings

In order to more clearly describe the embodiments of the present application or the technical solutions in the background art, the following description will describe the drawings that are required to be used in the embodiments of the present application or the background art.

Fig. 1 is a schematic structural diagram of an ultrasonic fingerprint recognition module in the prior art according to an embodiment of the present application.

Fig. 2 is a schematic diagram of an application scenario provided in an embodiment of the present application.

Fig. 3A is a schematic structural diagram of an ultrasonic fingerprint recognition module according to an embodiment of the present application.

Fig. 3B is a schematic structural diagram of several pixel electrode units according to an embodiment of the present application.

Fig. 4 is a schematic diagram of states of a pixel electrode unit in a transmitting mode and a receiving mode according to an embodiment of the present application.

Fig. 5 is a schematic circuit diagram of an ultrasonic fingerprint recognition module in a transmitting mode according to an embodiment of the present application.

Fig. 6 is a schematic circuit diagram of an ultrasonic fingerprint recognition module in a receiving mode according to an embodiment of the present application.

Fig. 7 is a schematic circuit diagram corresponding to an electrode control module according to an embodiment of the present application.

Fig. 8 is a timing chart corresponding to an ultrasonic fingerprint recognition module according to an embodiment of the present application.

Fig. 9 is a schematic circuit diagram corresponding to another electrode control module according to an embodiment of the present application.

Fig. 10 is a diagram of several fingerprint recognition systems according to embodiments of the present application.

Detailed Description

Embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application.

The terms "first," "second," "third," and "fourth" and the like in the description and in the claims and drawings are used for distinguishing between different objects and not necessarily for describing a particular sequential or chronological order. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those listed steps or elements but may include other steps or elements not listed or inherent to such process, method, article, or apparatus.

It should be understood that in the present application, "at least one (item)" means one or more, and "a plurality" means two or more. "and/or" for describing the association relationship of the association object, the representation may have three relationships, for example, "a and/or B" may represent: only a, only B and both a and B are present, wherein a, B may be singular or plural. The character "/" generally indicates that the context-dependent object is an "or" relationship. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, at least one (one) of a, b or c may represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", wherein a, b, c may be single or plural.

For ease of description, embodiments of the application may use spatial relational terms such as "under," "below," "beneath," "above," "upper," and the like to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that these spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary words "below" and "beneath" can encompass both an orientation of above and below. The device may have other orientations (rotated 90 degrees or in other orientations) and the spatially relative descriptors used herein 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 one or more intervening layers may also be present.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

As used in this specification, the terms "component," "module," "system," and the like are intended to refer to a computer-related entity, either hardware, firmware, a combination of hardware and software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a computing device and the computing device can be a component. One or more components may reside within a process and/or thread of execution and a component may be localized on one computer and/or distributed between 2 or more computers. Furthermore, these components can execute from various computer readable media having various data structures stored thereon. The components may communicate by way of local and/or remote processes such as in accordance with a signal having one or more data packets (e.g., data from two components interacting with one another in a local system, distributed system, and/or across a network such as the internet with other systems by way of the signal).

First, in order to facilitate understanding of the embodiments of the present application, the technical problems to be solved by the embodiments of the present application are specifically analyzed below.

Referring to fig. 1, fig. 1 is a schematic structural diagram of an ultrasonic fingerprint recognition module in the prior art according to an embodiment of the present application.

As shown in fig. 1, the conventional ultrasonic fingerprint recognition module scheme and its corresponding pixel circuit electrode scheme. As shown in fig. 1 (1), the ultrasonic fingerprint module is adhered below a target area of a display screen (such as an organic light emitting diode (Organic Light Emitting Diode, OLED) display screen) through an adhesive layer. The target area is an area for identifying fingerprints in the display screen. The ultrasonic fingerprint identification module includes: a circuit substrate, a piezoelectric layer, a common electrode layer (e.g., ag electrode), etc. The circuit board may include a pixel circuit, a pixel electrode, and the like on the surface of the board, and the circuit may be a thin film field effect transistor (Thin Film Transistor, TFT) circuit, a complementary metal oxide transistor (Complementary Metal Oxide Semiconductor, CMOS) circuit, or the like. The piezoelectric layer is a Copolymer organic composite material taking polyvinylidene fluoride PVDF as a core raw material, and the like. Taking a TFT substrate as an example (i.e., a pixel circuit is a TFT circuit). As shown in fig. 1 (2), a partially enlarged side view of the pixel electrode is provided below the TFT circuit and connected to the piezoelectric layer. As shown in fig. 1 (3), in some embodiments, the pixel electrodes are arranged in an array on the piezoelectric layer, and the pixel electrodes on the TFT circuit may be tin-doped indium oxide (Indium Tin Oxides, ITO) electrodes, and the Gap between adjacent pixel ITO electrodes is about 5um.

However, the ultrasonic fingerprint recognition module shown in fig. 1 also has the following problems:

the penetrating power of the ultrasonic wave that current ultrasonic fingerprint identification module sent is not enough, especially is applied to the terminal equipment of the display screen that has toughened glass film, or when being applied to the terminal equipment that the display screen is too thick, too thick display screen or the toughened film on the display screen can influence the penetration of ultrasonic wave for the echo signal volume size that the ultrasonic wave reflection was back, and then can lead to the unable fingerprint information of discernment effectively of ultrasonic fingerprint identification module.

In addition, the ultrasonic fingerprint recognition module is tightly attached to the lower portion of the screen, and the echo Signal is provided with a large number of signals reflected by other devices, so that an original Signal-to-noise ratio (SNR) corresponding to the fingerprint image is smaller, and the ultrasonic fingerprint recognition module cannot accurately recognize fingerprint information.

In this regard, the embodiment of the application provides an ultrasonic fingerprint identification module, which can reduce the equivalent capacitance corresponding to the piezoelectric layer in the transmitting mode under the condition that the equivalent capacitance corresponding to the piezoelectric layer in the receiving mode is unchanged by controlling the state of the pixel electrode in different modes under the condition that the light transmittance of a display screen is gradually reduced or a cover plate is covered above the display screen, so as to improve the overall efficiency of a conversion path between an electric signal and an acoustic signal, thereby increasing the quantity of a reflected echo signal and improving the original signal to noise ratio corresponding to a fingerprint image, and accurately and effectively identifying fingerprint information. For example: the side, close to the piezoelectric layer, of the circuit substrate comprises a plurality of pixel electrode units which are arranged in an array mode, each pixel electrode unit comprises N first pixel electrodes and M second pixel electrodes, and N and M are integers which are larger than or equal to 1. One side of the piezoelectric layer is electrically connected with the common electrode, and the other side of the piezoelectric layer is electrically connected with the pixel electrode units; under the condition that the ultrasonic fingerprint identification module is in a transmitting mode, the N first pixel electrodes are in a communicating state, and the M second pixel electrodes are in a suspending state; and under the condition that the ultrasonic fingerprint identification module is in a receiving mode, the N first pixel electrodes and the M second pixel electrodes are in the communication state. The specific implementation manner of the embodiment of the present application may also refer to the following related embodiments, which are not described herein for brevity.

Secondly, based on the technical problems mentioned above, in order to facilitate understanding of the embodiments of the present application, a description is first given of one of the ultrasonic fingerprint recognition modules on which the embodiments of the present application are based.

The embodiment of the application provides an ultrasonic fingerprint identification module, which comprises: the piezoelectric display device comprises a public electrode, a piezoelectric layer and a circuit substrate, wherein the public electrode, the piezoelectric layer and the circuit substrate are arranged in a stacked mode, one side, close to the piezoelectric layer, of the circuit substrate comprises a plurality of pixel electrode units which are arranged in an array mode, each pixel electrode unit comprises N first pixel electrodes and M second pixel electrodes, and N and M are integers which are larger than or equal to 1. One side of the piezoelectric layer is electrically connected with the common electrode, and the other side of the piezoelectric layer is electrically connected with the plurality of pixel electrode units. Under the condition that the ultrasonic fingerprint identification module is in a transmitting mode, the N first pixel electrodes are in a communicating state, and the M second pixel electrodes are in a suspending state; and under the condition that the ultrasonic fingerprint identification module is in a receiving mode, the N first pixel electrodes and the M second pixel electrodes are in the communication state.

Referring to fig. 2, fig. 2 is a schematic diagram of an application scenario provided by an embodiment of the present application, where the ultrasonic fingerprint recognition module may be applied to an electronic device, and the electronic device may perform fingerprint recognition by using the ultrasonic fingerprint recognition module to unlock the electronic device. As shown in fig. 2, the electronic device may include a display screen 100, and an ultrasonic fingerprint recognition module 10 may be attached below a target area in the display screen 100, and the size of the ultrasonic fingerprint recognition module 10 may be slightly larger than or equal to the target area and used for transmitting ultrasonic waves to recognize fingerprint information of a user.

It should be noted that the material of the display 100 is not particularly limited in the embodiments of the present application. For example: the display screen may be a quantum dot light emitting diode (quantum dotlight emitting diodes, QLED) display device, an active-matrix organic light emitting diode (AMOLED) display device, or the like.

It should be further noted that, besides the display screen, the ultrasonic fingerprint recognition module in the embodiment of the application may also be disposed in or under a cover plate, where the cover plate may be a glass cover plate or a metal cover plate, and the material of the cover plate is not specifically limited in the embodiment of the application.

It should be noted that, the ultrasonic fingerprint recognition module in the embodiment of the present application may also directly perform fingerprint recognition without being encapsulated or covered. For example: under the condition that the ultrasonic fingerprint recognition module is packaged or covered by the display screen or the cover plate, namely, the ultrasonic fingerprint recognition module is arranged on the substrate and is directly exposed under the fingers of a user, the ultrasonic fingerprint recognition module can conduct fingerprint recognition.

In addition, the ultrasonic fingerprint recognition module 10 provided by the embodiment of the application can be applied to various scenes of palm prints and even foot prints by utilizing ultrasonic waves, for example: the under-screen ultrasonic fingerprint recognition module 10 is used in the punch to perform fingerprint recognition to complete punching, and the embodiment of the application is not limited in detail.

In addition, in the embodiment of the present application, n=1, m=1, and the ultrasonic fingerprint recognition module is disposed below the display screen, the above-mentioned ultrasonic fingerprint recognition module 10 is exemplified. Referring to fig. 3A, fig. 3A is a schematic structural diagram of an ultrasonic fingerprint recognition module according to an embodiment of the present application.

As shown in fig. 3A (1), the ultrasonic fingerprint recognition module 10 is attached to the display screen 100 directly below the target area by an adhesive layer, and the ultrasonic fingerprint recognition module 10 includes: the common electrode 101, the piezoelectric layer 102 and the circuit substrate 103 are stacked, the circuit substrate 103 may be used to support the common electrode 101 and the piezoelectric layer 102 and is fixed below the display screen 100 through an adhesive layer, a side of the circuit substrate 103 near the piezoelectric layer 102 includes a plurality of pixel electrode units 1031 arranged in an array, and each pixel electrode unit 1031 includes n=1 first pixel electrodes 201 and m=1 second pixel electrodes 202. In some embodiments, the ultrasound fingerprint recognition module 10 may also include a drive circuit 104.

As shown in (2) of fig. 3A, 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 substrate 103, which is used to support and insulate the direct electrical connection between the plurality of pixel electrode units.

As shown in (3) of fig. 3A, the side of the piezoelectric layer 102 near the circuit substrate 103 includes a plurality of pixel electrode units 1031 arranged in a matrix, and each pixel electrode unit 1031 includes one first pixel electrode 201 and one second pixel electrode 202. The materials of the first pixel electrode 201 and the second pixel electrode 202 may be indium tin oxide (Indium Tin Oxides, ITO), which is not particularly limited in the embodiment of the present application.

It will be understood that, as shown in (3) of fig. 3A, one pixel electrode unit corresponds to one pixel, and a repeating unit is disposed between each pixel electrode unit, that is, the connection relationship and the configuration of each pixel electrode unit are uniform, a plurality of pixel electrode units may be arranged on one side of the piezoelectric layer in an array, and a Gap exists between each pixel electrode unit in a horizontal or vertical direction, which may be, for example, 5 μm. In addition, it should be noted that, the horizontal and vertical directions are understood to be the horizontal or vertical directions along the display screen when the electronic device is used normally, and the embodiments of the present application are not limited in detail.

In other embodiments, the plurality of pixel electrode units may be arranged at intervals on one side of the piezoelectric layer, that is, the plurality of pixel electrode units may take on a circular shape, an elliptical shape, a rectangular shape, or other geometric shapes, which is not particularly limited.

In some embodiments, the one or more first pixel electrodes and the one or more second pixel electrodes may be understood as being formed by splitting a complete pixel electrode into complementary pixel sub-electrodes. For example: referring to fig. 3B, fig. 3B is a schematic structural diagram of several pixel electrode units according to an embodiment of the application. As shown in (1) of fig. 3B, the shapes of the first pixel electrode and the second pixel electrode in each pixel electrode unit may be different, and the first pixel electrode and the second pixel electrode are arranged on the piezoelectric layer side with their shapes being complementary. In other embodiments, the first pixel electrode and the second pixel electrode may be understood as pixel electrodes that are made of the same material, have the same structure, or have the same shape, but are connected in different modes. For example: as shown in (2) of fig. 3B described above, the first pixel electrode and the second pixel electrode in each pixel electrode unit may have the same shape and be arranged on the piezoelectric layer side. In addition, in addition to the arrangement manner shown in (2) in fig. 3B, the adjacent first pixel electrode and/or second pixel electrode in each pixel electrode unit may be arranged at intervals. For example: as shown in (3) of fig. 3B, the first pixel electrode and the second pixel electrode may be further arranged at intervals. In this regard, the shape, arrangement, and the like of the pixel electrodes are not particularly limited in the embodiment of the present application.

In some embodiments, taking one pixel electrode unit including one first pixel electrode and one second pixel electrode as an example, the sum of the sizes of the first pixel electrode and the second pixel electrode included in one pixel electrode unit in the horizontal or vertical direction may be less than or equal to one pixel. In other embodiments, the size of each first pixel electrode included in one pixel electrode unit or each second pixel electrode included in one pixel electrode unit in the horizontal or vertical direction may be less than or equal to one pixel. The embodiment of the present application is not particularly limited in this regard.

It should be noted that, the embodiments of the present application do not limit the number of the first pixel electrode and the second pixel electrode included in each pixel electrode unit, and the number ratio between the first pixel electrode and the second pixel electrode. The number or the number proportion can be comprehensively determined according to the size of the electronic equipment, the material of the display screen or the corresponding application scene and other factors. In other embodiments, the first pixel electrode and the second pixel electrode may be further switched by controlling a switching transistor. The embodiment of the present application is not particularly limited in this regard.

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

As shown in (3) of fig. 3B, a first gap exists between each pixel electrode unit, and a second gap exists between two adjacent pixel electrodes inside each pixel electrode unit, for example: as shown in (3) of fig. 3B, a second gap exists between the first pixel electrode and the second pixel electrode. The first gap can be larger than or equal to the second gap, so that effective fingerprint information can be obtained by better receiving the echo signals, and the accuracy of fingerprint identification is improved. In addition, the size of the first gap in the horizontal direction between the plurality of pixel electrode units may be different from the size of the first gap in the vertical direction. If a plurality of second voids exist in each pixel electrode unit, the dimensions of the second voids in the plurality of second voids may be the same or different, which is not particularly limited in the embodiment of the present application.

It should be noted that, in other embodiments, the first and second voids may be filled with an insulating material to maintain independent connection between each pixel electrode. In other embodiments, the insulating material filled in the first void and the insulating material filled in the second void may be the same or different, which is not particularly limited in this embodiment of the present application.

It will be appreciated that the pixel electrode cell structure in fig. 3B is merely a few exemplary implementations of embodiments of the present application, including but not limited to the above pixel electrode cell structures. For example: each pixel electrode unit includes a plurality of first pixel electrodes and a plurality of second pixel electrodes, i.e., N and M are integers greater than 1.

Under the condition that the ultrasonic fingerprint identification module is in a transmitting mode, the N first pixel electrodes are in a communicating state, and the M second pixel electrodes are in a suspending state; and under the condition that the ultrasonic fingerprint identification module is in a receiving mode, the N first pixel electrodes and the M second pixel electrodes are in the communication state. In the transmission mode, the piezoelectric layer may generate and transmit an ultrasonic signal based on a high-frequency alternating current to which the common electrode is connected; in the receiving mode, the piezoelectric layer can receive echo signals reflected by the ultrasonic signals and transmit high-frequency electric signals to the N first electrodes and the M second electrodes based on the echo signals, wherein the high-frequency electric signals are used for identifying fingerprint information by the ultrasonic fingerprint identification module.

When the ultrasonic fingerprint recognition module 10 shown in fig. 3A is in an operating state, the operating state can be divided into a transmitting mode and a receiving mode. For example, based on the above-mentioned structure of the ultrasonic fingerprint recognition module shown in fig. 3A, please refer to fig. 4, and fig. 4 is a schematic diagram illustrating states of the pixel electrode unit in the transmitting mode and the receiving mode according to an embodiment of the present application.

Among them, the transmission mode may be used to transmit ultrasonic waves, which may penetrate the adhesive layer and the display screen 100, etc. Under the condition that the ultrasonic fingerprint identification module is in a sending mode, a first pixel electrode in each pixel electrode unit is in a communicating state, and a second pixel electrode in each pixel electrode unit is in a suspending state. For example: as shown in fig. 4, the first pixel electrode 201 in each pixel electrode unit may be grounded, and the second pixel electrode 202 may not be grounded. When the first pixel electrode 201 is grounded, an electrostatic field grounded may be formed at one side of the piezoelectric layer for the piezoelectric layer to transmit ultrasonic waves.

The first pixel electrode being in the connected state means that the first pixel electrode is connected to a circuit for transmitting ultrasonic waves, that is, an electrostatic field is provided to one side of the piezoelectric layer when the first pixel electrode is in the connected state. The second pixel electrode being in a floating state means that the second pixel electrode is not connected to a circuit for transmitting ultrasonic waves. At this time, in the case where the common electrode is connected with the high-frequency alternating current, the piezoelectric layer receives electrostatic high voltage from both sides (wherein, one side is the direct current bias electric field provided by the first pixel electrode, and the other side is the high-frequency alternating current electric field provided by the common electrode), and the state is changed from the stationary state to the high-frequency mechanical vibration state in the thickness direction, that is, ultrasonic vibration is generated and transmitted, and the ultrasonic vibration can be transmitted to the display screen direction through the layers until encountering the finger pressed on the target area by the user, and part of the ultrasonic wave is reflected, and a small part continues to propagate forward.

Thus, in other embodiments, the first pixel electrode 201 in each pixel electrode unit may be in a connected state with a fixed level, and the second pixel electrode 202 may be in a floating state without a fixed level.

It should be noted that, when the electronic device recognizes the pressing signal of the user on the target area, the ultrasonic fingerprint recognition module 10 is only in the working state.

Referring to fig. 5, fig. 5 is a schematic circuit diagram of an ultrasonic fingerprint recognition module in a transmitting mode according to an embodiment of the present application. As shown in fig. 5, the driving circuit 104 of the ultrasonic fingerprint recognition module 10 further includes a driving chip and a board-level resonant circuit when the ultrasonic fingerprint recognition module is in the transmission mode. As shown in fig. 5 (1), in the transmission mode, N first pixel electrodes 201 in each pixel electrode unit 1031 are connected to ac ground through the output of the driving chip and the logic inside the circuit substrate 103. In addition, the driving chip can also output alternating-current pulse or sinusoidal voltage (e.g., -30V) to the board-level resonant circuit, and the board-level resonant circuit can output alternating-current signals (e.g., -100V) with greatly improved voltage values 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 grounded, and the common electrode 101 on the other side thereof forms an alternating electric field, thereby causing vibration (i.e., ultrasonic wave generation) of the piezoelectric layer.

As shown in fig. 5 (2), a schematic diagram of a corresponding transmission circuit structure in a transmission mode is shown, wherein 2 switching tubes can be driven by 2 groups of clock signals with opposite phases inside a driving chip, so that the complementary switching tubes are turned on or off in a time division manner. Output signals of the driving chip and corresponding equivalent capacitance C in an inductance L, a path resistance R and a piezoelectric layer transmission mode in the board-level resonant circuit _TX And (3) connecting in series. From the above, the final ultrasonic center working frequency of the ultrasonic fingerprint recognition module 10 is the resonant frequency of the LC Boost resonant circuit. Wherein the LC Boost resonant circuit has a resonant frequency of

The equivalent capacitance C of the piezoelectric layer in the transmission mode _TX Associated with the electrodes connected to both sides of the piezoelectric layer. Wherein, under the condition that the common electrode is unchanged, the equivalent capacitance C corresponding to the piezoelectric layer in the transmission mode _TX The number of the first pixel electrodes or the ratio of the number of the first pixel electrodes to the number of the second pixel electrodes in each pixel electrode unit at one side of the piezoelectric layer is changed. For example: when the ultrasonic fingerprint identification module is in a transmission mode, under the condition that the number of pixel electrodes included in the pixel electrode unit is fixed, the more the number of pixel electrodes (namely, first pixel electrodes) at one side of the piezoelectric layer is in a communicated state, the equivalent capacitance C corresponding to the piezoelectric layer in the transmission mode is larger _TX The larger the size; the more the number of pixel electrodes (i.e., second pixel electrodes) at one side of the piezoelectric layer in a suspended state, the corresponding equivalent capacitance C of the piezoelectric layer in the transmission mode _TX The smaller. It can be appreciated that the equivalent capacitance C of the piezoelectric layer in the transmit mode corresponds to _TX Positively correlated with the area of the pixel electrode in a connected state on both sides of the piezoelectric layer.

For example, at a certain time of the common electrode, the more the number of pixel electrodes at one side of the piezoelectric layer is in a connected state, the larger the electrode area of the connected circuit is, and the equivalent capacitance C corresponding to the piezoelectric layer in the transmitting mode is obtained _TX The larger. The smaller the number of pixel electrodes at one side of the piezoelectric layer in a connected state is, the smaller the electrode area of an accessed circuit is, and the equivalent capacitance C corresponding to the piezoelectric layer in a transmission mode is further reduced _TX The smaller. Therefore, in some embodiments, the ultrasonic fingerprint recognition module 10 can control the equivalent capacitance C corresponding to the piezoelectric layer transmission mode by controlling the number of the pixel electrodes in the connected state in the transmission mode _TX Is of a size of (a) and (b).

In addition, in order for the ultrasonic fingerprint recognition module to better recognize the fingerprint information of the user based on the echo signal reflected by the ultrasonic wave, the center working frequency of the ultrasonic wave sent in the embodiment of the application needs to be within the target resonance frequency range, for example, the target resonance frequency can be set to 5M-20MHZ. For this, based on the resonance frequency f=f ₀ Equivalent capacitance C in transmission mode _TX The inductance L in the board-level resonant circuit should satisfy the following formula:wherein f is ₀ The target resonant frequency is preset, and can be used for the ultrasonic fingerprint identification module to better identify fingerprint information of a user based on echo signals reflected by ultrasonic waves.

It should be noted that, for the LC Boost resonant circuit in the transmitting mode, if the power supply voltage of the driving chip is Vin and the output voltage across the piezoelectric layer is Vout, the voltage amplification factor in the transmitting mode is:

therefore, the amplification factor of the driving voltage of the ultrasonic fingerprint identification module in the transmission mode is strongly related to the LC circuit path resistance and the equivalent capacitance corresponding to the piezoelectric layer. Wherein, when the path resistance is determinedIn the case of C _TX The smaller the piezoelectric layer, i.e. the fewer the number of pixel electrodes in a connected state in each pixel electrode unit at one side of the piezoelectric layer, the larger the driving voltage amplification factor, the larger the vibration amplitude of the corresponding piezoelectric layer, which is more favorable for penetration of ultrasonic waves.

Under the condition that the ultrasonic fingerprint recognition module is in a receiving mode, the ultrasonic fingerprint recognition module can receive echo signals reflected back after the ultrasonic transmitted in the transmitting mode encounters a finger (such as a finger valley and a finger ridge) of a user, and at the moment, N first pixel electrodes and M second pixel electrodes in each pixel electrode unit are in the communication state.

The first pixel electrode and the second pixel electrode are both in a communication state, which means that the first pixel electrode and the second pixel electrode are both connected to a circuit for receiving and reading echo signals. When receiving the echo signals, the echo signals of the reflected ultrasonic waves pass through each layer of medium and reach the piezoelectric layer, so that the piezoelectric layer which is close to static in a receiving mode is driven by the reflected echo signals to reenter a high-frequency vibration state, and the piezoelectric layer can convert high-frequency vibration into high-frequency electric signals (such as pulse signals or sine wave signals). The high-frequency electric signal can be received by a pixel electrode (such as a first pixel electrode and a second pixel electrode) which is positioned at one side of the piezoelectric layer and is in a communication state in a pixel electrode unit, and is transmitted to a related circuit for identifying the echo signal, and finally fingerprint information corresponding to the echo signal is identified and obtained. For example: an ultrasound imaged fingerprint image.

It can be understood that after the ultrasonic wave is sent, the ultrasonic fingerprint recognition module can be switched from a sending mode to a receiving mode, and high-frequency electric fields cannot be formed on two sides of the piezoelectric layer at the moment, so that the high-level mechanical vibration of the piezoelectric layer can be gradually stopped due to damping, and the piezoelectric layer is restored to a static state.

In some embodiments, the circuit substrate further includes a reading module, where the reading module 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 being connected to the reading module.

As shown in fig. 4, in the case where the ultrasonic fingerprint recognition module is in the receiving mode, the first pixel electrode 201 in each pixel electrode unit 1031 and the second pixel electrode 202 in each pixel electrode unit 1031 may be connected to a reading module for reading an electric signal, that is, the reading module may read fingerprint information based on a high-frequency electric signal transmitted by the first pixel electrode and the second pixel electrode, and the piezoelectric layer is based on a high-frequency electric signal generated by an echo signal.

It is understood that the reading module may be integrated in the driving chip shown in fig. 5, besides the circuit substrate, which is not particularly limited in this embodiment of the present application.

Referring to fig. 6, fig. 6 is a schematic circuit diagram of an ultrasonic fingerprint recognition module in a receiving mode according to an embodiment of the present application. As shown in (1) of fig. 6, the pixel electrode unit 1031 in the receiving mode is connected to the reading module. As shown in (2) of fig. 6, an echo signal of the reflected echo is converted into a high-frequency electric signal by the piezoelectric layer, for example: can be expressed as V _RX Voltage of V for each pixel electrode unit _RX Will be correspondingly equivalent capacitance C by the piezoelectric layer in the receiving mode _RX And parasitic capacitance C corresponding to pixel electrode unit ₀ Partial pressure of V _{RX_eff} The voltage of the voltage is the effective voltage which can be read by the subsequent reading module. Therefore, the proportion relation of the ultrasonic echo voltage and the effective reading voltage in the ultrasonic reading stage is as follows:therefore, the greater the ratio of the ultrasonic echo voltage and the effective read voltage in the ultrasonic read stage, i.e., the higher the original signal-to-noise corresponding to the fingerprint information.

When the ultrasonic fingerprint recognition module is in the receiving mode, under the condition that the number of the pixel electrodes included in the pixel electrode unit is fixed, the more the number of the pixel electrodes (namely, the first pixel electrode and the second pixel electrode) are in a communicated state at one side of the piezoelectric layer, the equivalent capacitance C corresponding to the piezoelectric layer in the receiving mode is larger _TX The larger the size; the more the number of pixel electrodes at one side of the piezoelectric layer in a suspended state, the corresponding equivalent capacitance C of the piezoelectric layer in a receiving mode _TX The smaller. It can be appreciated that the equivalent capacitance C of the piezoelectric layer in the receiving mode _TX The area of the pixel electrode connected to both sides of the piezoelectric layer is also positively correlated. That is, the more the number of pixel electrodes on one side of the piezoelectric layer is in a connected state, the larger the electrode area of the receiving circuit is accessed, and the equivalent capacitance C corresponding to the piezoelectric layer in the receiving mode is further increased _TX The larger.

According to the above analysis, in the receiving mode, when the parasitic capacitance C corresponding to the pixel electrode unit ₀ When the piezoelectric layer receives the corresponding equivalent capacitance C in the mode _RX The larger the capacitance of the piezoelectric layer, i.e., the larger the number of pixel electrodes (i.e., the first pixel electrode and the second pixel electrode) in a connected state on one side of the piezoelectric layer, the higher the reading efficiency in the receiving mode, the higher the original signal-to-noise corresponding to the corresponding fingerprint information, which can be understood as fingerprint image information.

To sum up, in the embodiment of the present application, in order to improve the system efficiency, in the case that the ultrasonic fingerprint recognition module is in the transmission 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 part of the pixel electrodes in each pixel electrode unit are in a connected state; and under the condition that the ultrasonic fingerprint identification module is in a receiving mode, the N first pixel electrodes and the M second pixel electrodes are in the communication state, namely all pixel electrodes in each pixel electrode unit are in the communication state, or more pixel electrodes in each pixel electrode unit than in a sending mode are in the communication state. Therefore, the number of the pixel electrodes in the communication state in different modes can be used to enable the equivalent capacitance corresponding to the piezoelectric layer in the sending mode to be smaller than that corresponding to the piezoelectric layer in the receiving mode, so that the ultrasonic fingerprint recognition module can be based on the electrode structure of the pixel corresponding to the pixel electrodes, the penetrating capacity of ultrasonic waves in the sending mode is improved, the original signal noise corresponding to the fingerprint image in the receiving mode is increased, and the accuracy of fingerprint information recognition of the ultrasonic fingerprint recognition module is improved.

In some embodiments, the circuit substrate further comprises an electrode control module comprising one or more switching tubes; each switching tube is correspondingly connected with one or more second pixel electrodes in the M second pixel electrodes, and each second pixel electrode corresponds to one switching tube; when the ultrasonic fingerprint identification module is in the sending mode, the one or more switch tubes are turned off so as to control all second pixel electrodes of the M second pixel electrodes to be in the suspended state; and under the condition that the ultrasonic fingerprint identification module is in the receiving mode, the one or more switch tubes are conducted so as to control all second pixel electrodes of the M second pixel electrodes to be in the communication state.

The electrode control module can regulate and control the connection state of the second pixel electrode in the pixel electrode unit under different modes through one or more switch tubes. Each switching tube can be connected with one or more second pixel electrodes in the M second pixel electrodes so as to control all the second pixel electrodes in the M second pixel electrodes to be in a suspended state in a sending mode and to be in a communicating state in a receiving mode. Referring to fig. 7, fig. 7 is a schematic circuit diagram corresponding to an electrode control module according to an embodiment of the present application, taking a receiving mode as an example, the electrode control module includes one or more switching tubes, as shown in (1) in fig. 7, a switching tube M1 may control a second pixel electrode 202; as shown in (2) of fig. 7, one switching tube M1 may control two second pixel electrodes 202. The switching tube M1 can control the corresponding second pixel electrode to be in a suspended state in a transmitting mode and to be in a communicating state in a receiving mode.

In some embodiments, each of the switching tubes includes a control end, a first end, and a second end; the control end is used for receiving a control signal, and the control signal is used for controlling the on or off of the corresponding switching tube; the first end is connected with a second pixel electrode controlled by the switch tube, and the second end is connected with the reading module. As shown in (3) of fig. 7, each switching tube M1 includes three terminals, namely: a control end, a first end and a second end. The switching tube can receive a control signal through the control end and control the on or off of the switching tube, so that the connection state of the second pixel electrode is controlled by adjusting the on or off of the switching tube. In addition, the selection of the type of the switching tube can be determined according to the application scene. For example: the switching tube can be an N-type switching tube or a P-type switching tube. For example, when the switching tube is an N-type switching tube, the control end may be a gate of the switching tube, the first end may be a drain of the switching tube, and the second end may be a source of the switching tube.

Referring to fig. 8, fig. 8 is a timing chart corresponding to an ultrasonic fingerprint recognition module according to an embodiment of the present application. As shown in fig. 8, the control signal is at a low level in the transmission mode (i.e., when the piezoelectric layer is subjected to high-frequency alternating current), wherein the switching tube is turned off in the low level, so as to control the corresponding second pixel electrode to be in a floating state; the control signal is in a high level in a receiving mode, wherein the switching tube is conducted in the high level, so that the corresponding second pixel electrode is controlled to be in a communication state. In addition, as shown in fig. 8, after the receiving mode, the reading module may be turned on to perform fingerprint identification on the received high-frequency electric signal.

In other embodiments, the electrode control module includes M switching tubes, and each switching tube is connected to each second pixel electrode in a one-to-one correspondence.

Referring to fig. 9, fig. 9 is a schematic circuit diagram corresponding to another electrode control module provided in an embodiment of the present application, as shown in fig. 9 (1), each second pixel electrode is individually corresponding to a switching tube, and the electrode control module can more accurately control the connection or suspension of the second pixel electrode. In addition, as shown in (2) in fig. 9, each second pixel electrode is independently controlled by different switching tubes, so that the risk of low fingerprint identification accuracy caused by device errors is greatly reduced, and the success rate of fingerprint identification by the ultrasonic fingerprint identification module is ensured.

In other embodiments, the substrate further comprises an electrode control module comprising one or more switching tubes; each switching tube is correspondingly connected with one or more pixel electrodes. The electrode control module can regulate the number or the proportion of the first pixel electrode and the second pixel electrode in each pixel electrode unit. For example, each of the first pixel electrodes or each of the second pixel electrodes may correspond to one of the switching tubes. The electrode control module can control the connection state of the corresponding pixel electrodes through the switch tube, wherein the pixel electrode in the communication state in the transmission mode can be understood as a first pixel electrode, and the pixel electrode in the floating state in the transmission mode can be understood as a second pixel electrode. The first pixel electrode and the second pixel electrode can be mutually switched by the control of a switching tube. For example, when the received echo signal is not strong, the electrode control module can control the on or off of different switching tubes, so as to properly reduce the number of the first pixel electrodes and increase the number of the second pixel electrodes. The embodiment of the present application is not particularly limited in this regard.

In some embodiments, 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 substrate is a metal oxide transistor (CMOS) circuit substrate, and each switching tube is a metal oxide transistor (CMOS). It can be 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; when the circuit substrate is a metal oxide transistor CMOS circuit substrate, one or more switching transistors in the corresponding electrode control module are also metal oxide transistor CMOS. It can be understood that the TFT-type circuit substrate corresponds to the TFT switching tube, and the CMOS-type circuit substrate corresponds to the CMOS switching tube, so as to be better suitable for various application scenarios.

In summary, according to the ultrasonic fingerprint recognition module provided in the embodiment of the application, based on the electrode structure of the plurality of pixel electrodes corresponding to one pixel, the penetrating capability of the ultrasonic wave in the transmitting mode can be improved, the original signal-to-noise corresponding to the fingerprint image in the receiving mode can be increased, and the accuracy of fingerprint information recognition of the ultrasonic fingerprint recognition module can be further improved. Wherein, this ultrasonic fingerprint identification module can include: the common electrode, the piezoelectric layer, and the circuit substrate are stacked. The circuit substrate includes a plurality of pixel electrode units arranged in an array on a side close to the piezoelectric layer, each pixel electrode unit corresponds to one pixel, and each pixel electrode unit includes a plurality of pixel electrodes, for example, N first pixel electrodes and M second pixel electrodes. For example: a pixel electrode unit may include a first pixel electrode and a second pixel electrode. Compared with the condition that one pixel corresponds to only one pixel electrode in the prior art, one pixel can correspond to a plurality of pixel electrodes, and accuracy of identifying fingerprint information can be improved better. In addition, the pixel electrodes are independent of each other, that is, the connection states of the first pixel electrode and the second pixel electrode in the pixel electrode unit may be different, for example: under the condition that the ultrasonic fingerprint identification module is in a transmitting mode, N first pixel electrodes are in a communicating state, and M second pixel electrodes are in a suspending state; under the condition that the ultrasonic fingerprint identification module is in a receiving mode, the N first pixel electrodes and the M second pixel electrodes are in a communicating state. In the transmitting mode, only part of pixel electrodes (such as N first pixel electrodes) in each pixel electrode unit are connected to a circuit for transmitting ultrasonic waves, and compared with all the pixel electrodes in a communicating state, the transmitting mode can greatly improve the corresponding amplification coefficient when transmitting the ultrasonic waves, so that the penetrating capacity of the ultrasonic waves is improved, and the ultrasonic waves are easier to penetrate through each layer. All pixel electrodes are connected into a circuit for receiving echo signals in a receiving mode, and part of pixel electrodes are communicated in the transmitting mode and all pixel electrodes are communicated in the receiving mode, so that the proportion of effective voltage reading in the receiving mode can be improved, namely, the original signal-to-noise corresponding to a fingerprint image in the receiving mode is increased, and the accuracy of fingerprint information identification of an ultrasonic fingerprint identification module is improved better.

The embodiment of the application also provides a fingerprint identification system, which comprises an ultrasonic fingerprint identification module, wherein the ultrasonic fingerprint identification module can be the ultrasonic fingerprint identification module related to the related embodiment shown in the figures 2-9.

The fingerprint recognition system may further comprise a cover plate or a display. Referring to fig. 10, fig. 10 is a schematic diagram of several fingerprint recognition systems according to embodiments of the present application. As shown in fig. 10 (1), the fingerprint recognition system may further include a cover plate, which may be one of a glass cover plate, a metal cover plate, and a plastic cover plate, and the ultrasonic fingerprint recognition module may be fixed below the cover plate through an adhesive layer, so as to be used for recognizing the fingerprint information when detecting a fingerprint recognition operation acting on the cover plate. As shown in (2) of fig. 10, the ultrasonic fingerprint recognition module of the fingerprint recognition system may be uncovered and directly exposed to the finger of the user whose fingerprint is to be recognized, and at this time, the ultrasonic fingerprint recognition module may be supported by the substrate.

In addition, it should be noted that the ultrasonic fingerprint recognition module may be embedded in the substrate, or may be located on the substrate, and the specific position of the ultrasonic fingerprint recognition module is not specifically limited in the embodiment of the present application.

It should be further noted that, the ultrasonic fingerprint recognition module may be fixed below the cover plate through the adhesive layer, and may also be located inside the cover plate, which is not limited in particular by the embodiment of the present application.

The embodiment of the application also provides electronic equipment, which comprises a display screen and the ultrasonic fingerprint identification module related to the related embodiment shown in the figures 2-9, wherein the electronic equipment is used for identifying fingerprint information based on the ultrasonic fingerprint identification module under the condition that touch operation on the display screen is identified. The ultrasonic fingerprint recognition module can be positioned in or under the display screen, and the application is not particularly limited.

It should be understood that, the fingerprint identification system or the electronic device provided in the embodiment of the present application is consistent with the ultrasonic fingerprint identification module related to the related embodiments shown in fig. 2 to fig. 9, and the specific content and the beneficial effects thereof may refer to the ultrasonic fingerprint identification module related to the related embodiments shown in fig. 2 to fig. 9, which are not repeated here.

In the foregoing embodiments, the descriptions of the embodiments are emphasized, and for parts of one embodiment that are not described in detail, reference may be made to related descriptions of other embodiments.

It should be noted that, for simplicity of description, the foregoing method embodiments are all described as a series of acts, but it should be understood by those skilled in the art that the present application is not limited by the order of acts described, as some steps may be performed in other orders or concurrently in accordance with the present application. Further, those skilled in the art will also appreciate that the embodiments described in the specification are all preferred embodiments, and that the acts and modules referred to are not necessarily required for the present application.

In the several embodiments provided by the present application, it should be understood that the disclosed apparatus may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, such as the above-described division of units, merely a division of logic functions, and there may be additional manners of dividing in actual implementation, such as multiple units or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, or may be in electrical or other forms.

The units described above as separate components may or may not be physically separate, and components shown as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in the embodiments of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.

The integrated units described above, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on this understanding, the technical solution of the present application may be embodied in essence or a part contributing to the prior art or all or part of the technical solution, in the form of a software product stored in a storage medium, including several instructions for causing a computer device (which may be a personal computer, a server or a network device, etc., in particular may be a processor in the computer device) to perform all or part of the steps of the above-mentioned method according to the embodiments of the present application. Wherein the aforementioned storage medium may comprise: various media capable of storing program codes, such as a U disk, a removable hard disk, a magnetic disk, a compact disk, a Read-Only Memory (abbreviated as ROM), or a random access Memory (Random Access Memory, abbreviated as RAM), are provided.

The above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An ultrasonic fingerprint identification module, which is characterized by comprising: the piezoelectric display device comprises a public electrode, a piezoelectric layer and a circuit substrate which are arranged in a stacked manner, wherein one side, close to the piezoelectric layer, of the circuit substrate comprises a plurality of pixel electrode units which are arranged in an array manner, each pixel electrode unit corresponds to one pixel, each pixel electrode unit comprises N first pixel electrodes and M second pixel electrodes, and N and M are integers which are larger than or equal to 1; one side of the piezoelectric layer is electrically connected with the common electrode, and the other side of the piezoelectric layer is electrically connected with the pixel electrode units;

under the condition that the ultrasonic fingerprint identification module is in a transmitting mode, the N first pixel electrodes are in a communicating state, and the M second pixel electrodes are in a suspending state;

And under the condition that the ultrasonic fingerprint identification module is in a receiving mode, the N first pixel electrodes and the M second pixel electrodes are in the communication state.

2. The module of claim 1, wherein in the transmit mode, the N first pixel electrodes are in the connected state by a connected dc bias.

3. The module according to claim 1 or 2, wherein the circuit substrate further comprises a reading module for identifying fingerprint information;

in the receiving mode, the N first pixel electrodes and the M second pixel electrodes are in the connected state by being connected to the reading module.

4. A module according to claim 3, wherein the circuit substrate further comprises an electrode control module comprising one or more switching tubes; each switching tube is correspondingly connected with one or more second pixel electrodes in the M second pixel electrodes, and each second pixel electrode corresponds to one switching tube;

when the ultrasonic fingerprint identification module is in the sending mode, the one or more switch tubes are turned off so as to control all second pixel electrodes of the M second pixel electrodes to be in the suspended state;

And under the condition that the ultrasonic fingerprint identification module is in the receiving mode, the one or more switch tubes are conducted so as to control all second pixel electrodes of the M second pixel electrodes to be in the communication state.

5. The module of claim 4, wherein the electrode control module comprises M switching tubes, 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 switching tubes includes a control end, a first end, and a second end;

the control end is used for receiving a control signal, and the control signal is used for controlling the on or off of the corresponding switching tube; the first end is connected with a second pixel electrode controlled by the switch tube, and the second end is connected with the reading module.

7. The module of any one of claims 4-6, wherein 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 substrate is a metal oxide transistor (CMOS) circuit substrate, and each switching tube is a metal oxide transistor (CMOS).

8. The module of any one of claims 1-6, wherein a first gap exists between each 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, and the first gap is greater than or equal to the second gap.

9. A fingerprint identification system, characterized in that the fingerprint identification system comprises an ultrasonic fingerprint identification module according to any one of claims 1-8, the ultrasonic fingerprint identification module being adapted to identify fingerprint information.

10. An electronic device, characterized in that the electronic device comprises a display screen and the ultrasonic fingerprint recognition module according to any one of claims 1-8, and the electronic device recognizes fingerprint information based on the ultrasonic fingerprint recognition module when recognizing a touch operation acting on the display screen.