Ultrasonic fingerprint sensor detection method, identification module and storage medium

Abstract

The embodiment of the invention relates to the field of ultrasonic sensors, and discloses an ultrasonic fingerprint sensor detection method, an identification module and a storage medium. The ultrasonic fingerprint sensor detection method comprises the following steps: selecting a plurality of pixel units from a pixel array of an ultrasonic fingerprint sensor as center units; selecting a plurality of pixel units at the periphery of the central unit, and forming a transmitting unit set together with the central unit; transmitting signals are collected by using the transmitting unit, and echo signals corresponding to the transmitting signals are received by using the central unit; and repeatedly executing the step of selecting the central unit and the corresponding transmitting unit set until the pixel units in the pixel array are all used as the central units to complete the receiving of the echo signals. According to the invention, the emission signal is enhanced, the signal-to-noise ratio of the ultrasonic fingerprint sensor is optimized, and the contrast ratio of the ultrasonic fingerprint sensor for identifying the valley and ridge areas of the fingerprint is improved, so that the detection performance of the ultrasonic fingerprint sensor is optimized.

Description

Technical Field

[0001] The present invention relates to the field of ultrasonic sensors, and in particular to an ultrasonic fingerprint sensor detection method, an identification module and a storage medium. Background Art

[0002] Ultrasonic sensors utilize the direct and inverse piezoelectric properties of piezoelectric materials. Through the inverse piezoelectric effect, a high voltage output by the driver circuit excites the sensor to emit an ultrasonic signal. Through the direct piezoelectric effect, the reflected ultrasonic signal is converted into an electrical signal, thereby acquiring information about the sensing surface. After decades of development, ultrasonic sensors are now widely used in medical imaging, structural flaw detection, and biometric identification. For example, ultrasonic sensors can be applied to ultrasonic fingerprint modules, placed in specific areas of the screens of electronic devices, including but not limited to smartphones, for fingerprint recognition, user authentication, and enhanced product anti-interference and security.

[0003] In the current traditional detection method, there are interference signals in the echo signals received from the outside world, and the interference signals will affect the signal-to-noise ratio of the fingerprint image, thereby affecting the imaging effect. Summary of the Invention

[0004] The purpose of the embodiments of the present invention is to provide an ultrasonic fingerprint sensor detection method, recognition module and storage medium. By selecting a central unit in a pixel array, a set of transmitting units consisting of the central unit and peripheral pixel units jointly transmits the signal to enhance the transmission signal, and only the central unit is used to receive the echo signal, thereby optimizing the signal-to-noise ratio of the ultrasonic fingerprint sensor and improving the contrast of the ultrasonic fingerprint sensor in identifying the valley and ridge areas of the fingerprint.

[0005] To solve the above technical problems, an embodiment of the present invention provides an ultrasonic fingerprint sensor detection method, comprising: selecting several pixel units in a pixel array of an ultrasonic fingerprint sensor as a central unit; selecting several pixel units around the central unit to form a transmitting unit set together with the central unit; using the transmitting unit set to transmit a signal, and using the central unit to receive an echo signal corresponding to the transmitted signal; and repeatedly performing the steps of selecting the central unit and the corresponding transmitting unit set until all pixel units in the pixel array serve as the central unit to complete the reception of the echo signal.

[0006] An embodiment of the present invention also provides an ultrasonic fingerprint recognition module, comprising: an ultrasonic fingerprint sensor and a processor; the ultrasonic fingerprint sensor is used to execute the above-mentioned ultrasonic fingerprint sensor detection method when the ultrasonic fingerprint recognition module is triggered by an external object to obtain a plurality of echo signals; the processor is used to identify the fingerprint information of the external object based on the received echo signals.

[0007] An embodiment of the present invention further provides a computer-readable storage medium storing a computer program, which implements the above-mentioned ultrasonic fingerprint sensor detection method when executed by a processor.

[0008] Compared with the prior art, the embodiment of the present invention selects several pixel units as the central unit in the pixel array of the ultrasonic fingerprint sensor, and selects several pixel units around the central unit to form a transmitting unit set together with the central unit. Each pixel unit in the transmitting unit set is used to transmit a signal, and then only the central unit is used to receive the echo signal of the signal transmitted by the transmitting unit set and reflected by the external object. By synchronizing the transmission of signals by several pixel units around the central unit, the transmission signal can be enhanced, thereby increasing the strength of the received echo signal. In addition, by using only the central unit as the receiving unit for receiving the echo signal, it is possible to avoid receiving interference signals that affect the signal-to-noise ratio of the ultrasonic fingerprint sensor, thereby improving the contrast of the ultrasonic fingerprint sensor in identifying the valley and ridge areas of the fingerprint.

[0009] In addition, the selecting of a pixel unit as a central unit in the pixel array of the ultrasonic fingerprint sensor includes: selecting a plurality of pixel units at intervals in the pixel array, each pixel unit serving as a central unit; wherein each central unit constitutes a transmitting unit set; and the plurality of transmitting unit sets synchronously transmit signals, and utilize each pixel unit to receive a corresponding echo signal.

[0010] In addition, the selecting a plurality of pixel units in the pixel array at intervals includes: selecting a plurality of pixel units in the pixel array based on a preset interval, wherein the preset interval is greater than 1 / 5 of a thickness of a contact piece of an external object.

[0011] In addition, the selecting of a plurality of pixel units around the central unit includes: selecting a plurality of pixel units adjacent to the central unit, or selecting a plurality of pixel units separated from the central unit by one pixel unit.

[0012] In addition, the transmitting unit set is a centrally symmetrical figure or an axially symmetrical figure; wherein, when the transmitting unit set is a centrally symmetrical figure, the central unit is at the center position; when the transmitting unit set is an axially symmetrical figure, the symmetry axis passes through the central unit.

[0013] In addition, the use of the emission unit set to transmit signals includes: the emission signals of all pixel units in the emission unit set are focused at a target focus; the delay time of the excitation signal corresponding to each pixel unit is determined based on the distance between the target focus and each pixel unit in the emission unit set; and the emission signal of the emission unit set is controlled based on the delay time.

[0014] In addition, the projection of the target focus toward the pixel array is located at the center of the central unit.

[0015] In addition, the selecting of several pixel units in the pixel array of the ultrasonic fingerprint sensor as the central unit includes: selecting a row of pixel units or a column of pixel units in the pixel array as the central unit; wherein the pixel units in adjacent rows or adjacent columns of the central unit and the central unit together constitute the emission unit set. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplifications do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0017] Figure 1 It is a structural diagram of the fingerprint detection principle based on the ultrasonic fingerprint sensor;

[0018] Figure 2 is a flow chart of the ultrasonic fingerprint sensor detection method according to an embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of the structure in which the edge pixel unit is used as the central unit according to an embodiment of the present solution;

[0020] Figure 4 is a schematic diagram of a transmission unit collection diagram according to an embodiment of the present invention;

[0021] Figure 5 is a schematic diagram of another transmission unit collection diagram according to an embodiment of the present invention;

[0022] Figure 6 is a schematic diagram of another transmission unit collection diagram according to an embodiment of the present invention;

[0023] Figure 7 is a schematic diagram of another transmission unit collection diagram according to an embodiment of the present invention;

[0024] Figure 8 is a schematic diagram of another transmission unit collection diagram according to an embodiment of the present invention;

[0025] Figure 9 is a schematic structural diagram of a signal circuit of a pixel unit according to an embodiment of the present invention;

[0026] Figure 10 is a schematic structural diagram of a control circuit for a pixel array according to an embodiment of the present invention;

[0027] Figure 11 Schematic diagram of the structure of the focusing method of the ultrasonic fingerprint sensor detection method according to the embodiment of the present invention;

[0028] Figure 12 This is a comparison chart of echo signal strength under different configurations of transmitting unit sets in the embodiment of this solution;

[0029] Figure 13 This is a comparison chart of signal-to-noise ratios under different configurations of transmitting unit sets according to an embodiment of this solution;

[0030] Figure 14 It is an overall flow chart of the ultrasonic fingerprint sensor detection method according to the embodiment of this solution. DETAILED DESCRIPTION

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more apparent, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will appreciate that many technical details are provided in the embodiments of the present invention to help readers better understand the present application. However, even without these technical details and the various variations and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented.

[0032] The following embodiments are divided for the convenience of description and should not constitute any limitation on the specific implementation of the present invention. The various embodiments can be combined with each other and referenced to each other under the premise of no contradiction.

[0033] Ultrasonic fingerprint sensor detection method is usually used in ultrasonic fingerprint sensors to detect fingerprints, such as Figure 1As shown, the ultrasonic fingerprint sensor is attached to the back of the contact piece of an external object (such as a screen), and the external object (such as a finger) will touch the front of the contact piece. The ultrasonic fingerprint sensor includes a sensor substrate, a bottom electrode, a piezoelectric layer, a top electrode and a protective layer. The bottom electrode is a pixel array composed of a series of pixel electrodes, each pixel electrode corresponds to a pixel unit (a pixel unit is composed of a pixel electrode, a piezoelectric layer area corresponding to the vertical direction of the pixel electrode and a top electrode area), and the unit size is at the level of tens of microns. When the ultrasonic fingerprint sensor is in the acoustic emission mode, all pixel electrodes of the bottom electrode are grounded, and the top electrode is used to apply an excitation signal to excite the piezoelectric layer to emit an ultrasonic signal; when the ultrasonic signal is reflected from different areas (valleys, ridges) on the surface of the finger, the ultrasonic sensor switches to the acoustic receiving mode, the top electrode is grounded, and each pixel unit of the bottom electrode is used to receive the voltage echo signal generated when the returned ultrasonic signal acts on the piezoelectric layer. In traditional fingerprint detection methods, all pixel units jointly transmit ultrasonic signals and receive echo signals. Since the time for the ultrasonic wave to be reflected back from the valley and ridge areas is different, the ultrasonic signal sent by all pixel units can be formed as follows Figure 1 The ultrasonic waveform echo signal shown in the figure. However, since all pixel units transmit the ultrasonic signal together, the echo signal after reflection from the finger is not completely perpendicular to the screen. During the echo signal return process, the signals are superimposed and synthesized. As a result, the echo signal received by the pixel unit is not only the signal reflected from the finger area perpendicular to the pixel unit, but also superimposed with echo signals from other non-perpendicular directions. For fingerprint recognition, except for the echo signal reflected from the finger area perpendicular to the pixel unit, the remaining superimposed echo signals are interference signals. When analyzing based on the echo signal with interference signals, the signal-to-noise ratio of the ultrasonic fingerprint sensor is affected, thereby affecting the contrast of the ultrasonic fingerprint sensor's recognition of the fingerprint valley and ridge areas.

[0034] In order to reduce the reception of interference signals, the present invention proposes an ultrasonic fingerprint sensor detection method, such as Figure 2 As shown, the following steps are included:

[0035] Step 201: Select several pixel units in the pixel array of the ultrasonic fingerprint sensor as central units.

[0036] Specifically, according to the scheme of this embodiment, all pixel units in the pixel array need to be selected as the central unit. When selecting, the edge pixels of the pixel array can be selected as the central unit. The number of pixel units in the central unit can be single or multiple, and the number of pixel units contained in the central unit is selected according to different situations. When selecting the central unit at the same time, one central unit can be selected, or multiple central units can be selected at the same time to improve processing efficiency. When multiple central units are selected at the same time, the multiple central units will synchronously transmit and receive signals. In the subsequent steps, the selection rules of the central unit in different situations and the fingerprint detection process under different central unit selection rules will be specifically described.

[0037] Step 202: Select a number of pixel units around the central unit to form a set of emission units together with the central unit.

[0038] Specifically, when the central unit is an edge pixel unit, such as Figure 3 As shown in , when the edge pixel is taken as the center unit, several pixel units around the edge pixel are selected to form a set of emission units together with the center unit. When the center unit is a non-edge pixel unit, that is, when there are other pixel units around the selected center unit, as shown in Figure 4 , we can select the pixel units adjacent to the central unit in four directions to form a set of emission units. Or Figure 5 As shown in FIG, eight pixel units around the central unit can be selected to form a set of emission units. Figure 6 As shown, the pixel units of the two layers around the central unit can be selected (such as Figure 6 The fourteen pixel units shown in FIG. 1 together constitute an emission unit set. Or as Figure 7 As shown, the pixel units that are in contact with the four corners of the central unit are selected to form a set of emission units. Figure 8 As shown, on the basis of selecting the pixel units that are in contact with the four corners of the central unit, four pixel units that are separated from the pixel unit by one pixel unit are further selected to form a set of emission units. In summary, when selecting the pixel units that constitute the emission unit set, several pixel units adjacent to the central unit can be selected, or several pixel units separated from the central unit by one pixel unit can be selected. Such a selection can ensure that the signal emitted by the selected pixel unit can enhance the emission signal of the central unit. The emission unit set finally forms a centrally symmetrical figure or an axially symmetrical figure, wherein when the emission unit set is a centrally symmetrical figure, the central unit is at the center position; when the emission unit set is an axially symmetrical figure, the axis of symmetry passes through the central unit.

[0039] Step 203: Utilize the transmitting unit set to transmit a signal, and utilize the central unit to receive an echo signal corresponding to the transmitted signal.

[0040] Specifically, the signal circuit of the pixel unit of the ultrasonic fingerprint sensor is as follows: Figure 9 As shown. The pixel unit is composed of a top electrode, a piezoelectric layer and a bottom electrode. The top electrode of the pixel unit is grounded, and the bottom electrode is connected to the transmitting channel (TX) through a high-voltage switch on the one hand, and to the receiving channel (RX) through a low-voltage switch on the other hand. The transmitting channel mainly includes a pulse transmitting circuit, and the receiving channel mainly includes an amplifying circuit, a filtering circuit and a sampling circuit. When the high-voltage switch control is connected to the transmitting channel TX, the low-voltage switch control is connected to the ground GND. At this time, the ultrasonic fingerprint sensor is in the acoustic emission mode. When the low-voltage switch control is connected to the receiving channel RX, the high-voltage switch control is connected to the ground GND. At this time, the ultrasonic fingerprint sensor is in the acoustic receiving mode. The transmitting channel and the receiving channel are finally connected to the imaging system to realize the system's control of the transmitting and receiving channels, and then realize the switching between the acoustic emission mode and the acoustic receiving mode.

[0041] Step 204: Determine whether all pixel units in the pixel array have completed receiving the echo signal as the central unit. If the determination result is no, return to step 201 and repeat steps 201 to 203. If the determination result is yes, proceed to step 205: Complete the reception of the echo signal of all pixel units.

[0042] Specifically, the pixel array control circuit of the ultrasonic fingerprint sensor is as follows: Figure 10 As shown, the top electrodes of the sensor are commonly grounded, and the bottom electrodes of the sensor are pixel electrodes arranged in an array. Each pixel unit can be controlled by controlling the pixel electrodes, that is, the transmission and reception signals of each pixel unit can be individually controlled by the row selection circuit and the column selection circuit, thereby achieving the situation where only the transmission unit set transmits signals when other pixel units do not transmit signals, and only the echo signal received by the central pixel is saved.

[0043] Compared with the prior art, the embodiment of the present invention selects several pixel units as the central unit in the pixel array of the ultrasonic fingerprint sensor, and selects several pixel units around the central unit to form a transmitting unit set together with the central unit. Each pixel unit in the transmitting unit set is used to transmit a signal, and then only the central unit is used to receive the echo signal of the signal transmitted by the transmitting unit set and reflected by the external object. By synchronizing the transmission of signals by several pixel units around the central unit, the transmission signal can be enhanced, thereby increasing the strength of the received echo signal. In addition, by using only the central unit as the receiving unit for receiving the echo signal, it is possible to avoid receiving interference signals that affect the signal-to-noise ratio of the ultrasonic fingerprint sensor, thereby improving the contrast of the ultrasonic fingerprint sensor in identifying the valley and ridge areas of the fingerprint.

[0044] Furthermore, when selecting a pixel unit as a central unit in the pixel array of an ultrasonic fingerprint sensor, multiple pixel units can be selected at intervals within the pixel array, with each pixel unit serving as a central unit. Each central unit forms a transmitting unit set. The multiple transmitting unit sets synchronously transmit signals and receive corresponding echo signals using each pixel unit. When selecting multiple central units simultaneously, the multiple pixel units are selected within the pixel array based on a preset interval greater than 1 / 5 of the thickness of the contact member of the external object (e.g., a screen). This prevents interference between the signals of the multiple central units, which could affect the signal-to-noise ratio (SNR) of the received echo signals. The selected multiple central units can each be assigned surrounding pixel units according to different rules, thereby forming transmitting unit sets with different patterns. Specifically, the selection rules for surrounding pixel units can be determined based on the location of the central unit. When the central unit is at an edge, pixel units in directions other than the edge are selected to form the transmitting unit set. When the central unit is not at an edge, pixel units surrounding the central unit are selected to form the transmitting unit set. The transmitting unit set composed of the selected multiple central units transmits signals synchronously, reducing the number of repetitions required to select the central unit, thereby saving time to complete echo signal collection and improving fingerprint detection efficiency.

[0045] Furthermore, for scenarios requiring shorter scan times, to further shorten the time required to collect echo signals, a row or column of pixels in the pixel array can be selected as the central unit. The pixels in the adjacent rows or columns of the central unit, along with the central unit, form a collection of transmitting units. This allows the system to complete the scan by simply performing row or column scans sequentially, significantly reducing scanning time.

[0046] In addition, when ultrasonic waves propagate in a medium, the sound waves emitted by different array elements will have a time difference due to the difference in paths. In order to enhance the sound pressure intensity, a specific delay time (Δt) can be applied to each array element so that the emission signals of all pixel units in the emission unit set are focused at the target focus, such as Figure 11 Specifically, the delay time of the excitation signal corresponding to each pixel unit can be determined according to the distance between the target focus and each pixel unit in the transmitting unit set; and the transmitting unit set can be controlled to transmit signals according to the delay time.

[0047] For example, when an N-dimensional emission unit set is selected for scanning, if the projection of the target focus position onto the emission unit set coincides with the center of the emission unit set, the excitation signal delay time of each pixel unit in the emission unit set can be set to:

[0048]

[0049] Where F represents the focal length (the distance from the projection of the target focus position to the emitting unit set), k represents the number of pixels between the pixel unit and the center pixel in the emitting unit set (for example, if the pixel unit is adjacent to the center pixel, k is 1; if the pixel unit is one pixel away from the center unit, k is 2), d is the array spacing, and c is the speed of ultrasound in the medium.

[0050] In addition, in order to ensure that the projection of the target focus toward the pixel array is located at the center of the central unit in different patterns of emission unit sets, the position of the focused target focus can be controlled by controlling the delay time.

[0051] For example, in order to ensure that the position of the target focus is deflected by a certain angle (θ) compared to the direction of sound propagation, the excitation signal delay time of each pixel unit in the emission unit set can be set to:

[0052]

[0053] By controlling the size change of the excitation signal delay time, the emission signals of all pixel units in the emission unit set can be controlled to be focused at any position. Therefore, when the central pixel is at any position in the emission unit set graph, the focus target position can be controlled to be directly above the central pixel, which plays the role of enhancing the emission signal and improves the flexibility of selecting the central pixel and the emission unit set.

[0054] Compared to the traditional solution where all pixel units transmit ultrasonic signals and receive echo signals, the detection method in the embodiment of the present invention significantly improves the performance of ultrasonic fingerprint sensors. Currently, the signal-to-noise ratio (SNR) of the fingerprint image is often used to characterize the performance of ultrasonic fingerprint sensors. The calculation formula is:

[0055]

[0056] in, is the average value of the dark stripe (fingerprint ridge area) signal in the image, σDark is the standard deviation of the dark stripe signal in the image, is the average value of the bright streaks (valleys) in the image, and σLight is the standard deviation of the dark streak signal. In applications such as ultrasonic fingerprint imaging, SNR is closely related to the resolution and contrast of the image. The higher the SNR, the greater the contrast between dark and light streaks in the fingerprint image.

[0057] like Figure 12As shown in the figure, the average value of the echo voltage signal received by a single pixel unit in the fingerprint ridge area and valley area under the detection method in the embodiment of the present invention and the traditional detection method. It can be seen that when the five adjacent pixels are transmitting simultaneously, the echo voltage value received by the center pixel of the array is already equal to the echo voltage value corresponding to the simultaneous transmission of the signal by all pixels. The ridge area echo voltage value corresponding to the simultaneous transmission of the signal by seven adjacent pixels is higher than the ridge area echo voltage value corresponding to the simultaneous transmission of the signal by all pixels. Figure 13 The figure shows the SNRs corresponding to the detection method according to the embodiment of the present invention and the traditional detection method. When two or more adjacent pixel units are used as signal transmission units, the SNR of the fingerprint image is superior to the SNR corresponding to the traditional method of synchronous transmission of all pixels (15.69dB). Preferably, when three adjacent pixel units are used as signal transmission units, the SNR of the fingerprint image is 22.5dB, an improvement of 119% compared to the traditional method. Therefore, the solution of the present invention has a significant effect on the performance optimization of ultrasonic fingerprint sensors.

[0058] Finally, in order to facilitate understanding of the overall concept of the present invention, the overall process of the detection method is described as follows: Figure 14 As shown, the process includes:

[0059] (a) Reset phase: This phase is the initialization phase of the control circuit, completing the reset of all registers or flip-flops in the circuit;

[0060] (b) Ultrasonic transmission phase: The control circuit selects a specified pixel unit and N surrounding pixel units in the pixel array through row and column selection lines. At this time, the common top electrode of the sensor is grounded, and the high-voltage switch under the selected pixel unit switches from ground to the transmission channel, generating an ultrasonic signal under the drive of the transmission pulse voltage;

[0061] (c) Echo reception stage: The ultrasonic signal is reflected from the finger contact surface back to the sensor. At this time, the control circuit selects the designated pixel unit in step (b) through the row and column selection lines. At this time, the common top electrode of the sensor is grounded, and the low-voltage switch under the designated pixel unit switches from ground to the receiving channel. Driven by the returning ultrasonic wave, the bottom electrode of the designated pixel senses a charge or voltage signal;

[0062] (d) Signal reading stage: The charge or voltage signal sensed by the specified pixel unit is sampled by the analog-to-digital converter (ADC) after detection, amplification, and filtering, and then stored in the chip memory;

[0063] (e) Loop execution: The control circuit repeatedly executes the transmit, receive, and read functions for the specified pixel and its surrounding N pixels in the X and Y directions of the sensor array (e.g., the X direction is the row direction and the Y direction is the column direction), with the number of pixels as the step size. This completes data acquisition for all pixels.

[0064] This approach maximizes ultrasonic emission intensity by selecting one to N adjacent pixel units surrounding a designated pixel unit (the central unit) as a common sound pressure emission set (the emission unit set). During signal reception, only the echo signal from the selected pixel unit (the central unit) is read. This operation is performed simultaneously on multiple pixel units within the pixel array, ultimately completing a complete traversal of the sensor array units, shortening traversal scanning time and improving detection efficiency.

[0065] Furthermore, compared to the traditional all-transmit-all-receive approach, this solution can reduce device power consumption. The signal-to-noise ratio of fingerprint images is more than doubled compared to traditional solutions, significantly improving fingerprint detection contrast and enhancing fingerprint recognition efficiency.

[0066] In addition, with respect to the focusing method, the deflection focusing method proposed in the present invention does not need to strictly limit the array arrangement pattern of the emission unit set, thereby improving the flexibility of detection, simplifying circuit design, and reducing device cost and power consumption.

[0067] The steps of the various methods above are divided only for the purpose of clear description. When implemented, they can be combined into one step or some steps can be split and decomposed into multiple steps. As long as they include the same logical relationship, they are within the scope of protection of the present invention. Adding insignificant modifications or introducing insignificant designs to the algorithm or process without changing the core design of the algorithm and process are all within the scope of protection of the invention.

[0068] Another feasible embodiment of the present invention relates to an ultrasonic fingerprint recognition module, comprising: an ultrasonic fingerprint sensor and a processor; the ultrasonic fingerprint sensor is used to execute the above-mentioned ultrasonic fingerprint sensor detection method when the ultrasonic fingerprint recognition module is triggered by an external object to obtain a plurality of echo signals; the processor is used to identify the fingerprint information of the external object based on the received echo signals.

[0069] Ultrasonic fingerprint recognition modules are mainly used in smartphones, tablets, smart door locks and other devices for biometric identity authentication, including biometric fingerprint recognition in scenarios such as mobile phone unlocking, mobile payment, and device encryption.

[0070] Compared with the related art, the ultrasonic fingerprint recognition module provided by the embodiment of the present invention realizes the recognition of biometric fingerprints through the detection method provided by the aforementioned embodiment. Therefore, it also has the technical effects provided by the aforementioned embodiment and will not be described in detail here.

[0071] An embodiment of the present invention relates to a computer-readable storage medium storing a computer program, which implements the above method embodiment when executed by a processor.

[0072] That is, those skilled in the art will understand that all or part of the steps in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a program, which is stored in a storage medium and includes a number of instructions for causing a device (which may be a single-chip microcomputer, chip, etc.) or a processor to execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, etc., various media that can store program code.

[0073] Those skilled in the art will appreciate that the above embodiments are specific embodiments for implementing the present invention, and that in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present invention.

Claims

1. A method for detecting an ultrasonic fingerprint sensor, characterized in that: include: Selecting a number of pixel units as central units in the pixel array of the ultrasonic fingerprint sensor; Selecting a plurality of pixel units around the central unit to form an emission unit set together with the central unit; Using the transmitting unit set to transmit a signal, and using the central unit to receive an echo signal corresponding to the transmitted signal; The step of selecting the central unit and the corresponding set of transmitting units is repeatedly performed until all pixel units in the pixel array serve as the central unit to complete the reception of the echo signal.

2. The ultrasonic fingerprint sensor detection method according to claim 1, characterized in that: The step of selecting a pixel unit as a central unit in a pixel array of the ultrasonic fingerprint sensor includes: Selecting a plurality of pixel units at intervals in the pixel array, each pixel unit serving as a central unit; wherein each central unit constitutes an emission unit set; The plurality of transmitting units transmit signals synchronously, and each pixel unit receives a corresponding echo signal.

3. The ultrasonic fingerprint sensor detection method according to claim 2, characterized in that: The step of selecting a plurality of pixel units at intervals in the pixel array comprises: A plurality of pixel units are selected in the pixel array based on a preset interval, the preset interval being greater than 1 / 5 of a thickness of a contact member of an external object.

4. The ultrasonic fingerprint sensor detection method according to claim 1, characterized in that: The selecting of a plurality of pixel units around the central unit includes: A plurality of pixel units adjacent to the central unit are selected, or a plurality of pixel units separated from the central unit by one pixel unit are selected.

5. The ultrasonic fingerprint sensor detection method according to claim 1 or 4, characterized in that: The emission unit set is a centrally symmetrical figure or an axially symmetrical figure; When the emission unit set is a centrally symmetrical figure, the central unit is located at the center; when the emission unit set is an axially symmetrical figure, the axis of symmetry passes through the central unit.

6. The ultrasonic fingerprint sensor detection method according to claim 1, characterized in that: The transmitting signal by using the transmitting unit set includes: The emission signals of all pixel units in the emission unit set are focused at the target focus; Determining the delay time of the excitation signal corresponding to each pixel unit according to the distance between the target focus and each pixel unit in the emission unit set; The transmitting unit set is controlled to transmit a signal according to the delay time.

7. The ultrasonic fingerprint sensor detection method according to claim 6, characterized in that: The projection of the target focus toward the pixel array is located at the center of the central unit.

8. The ultrasonic fingerprint sensor detection method according to claim 1, characterized in that: The step of selecting a plurality of pixel units as central units in the pixel array of the ultrasonic fingerprint sensor includes: A row of pixel units or a column of pixel units in the pixel array is selected as the central unit; wherein the pixel units in adjacent rows or columns of the central unit and the central unit together constitute the emission unit set.

9. An ultrasonic fingerprint recognition module, characterized in that: include: Ultrasonic fingerprint sensor and processor; The ultrasonic fingerprint sensor is configured to execute the ultrasonic fingerprint sensor detection method according to any one of claims 1 to 8 to obtain a plurality of echo signals when the ultrasonic fingerprint recognition module is triggered by an external object; The processor is configured to identify fingerprint information of the external object according to the received echo signal.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the ultrasonic fingerprint sensor detection method according to any one of claims 1 to 8 is implemented.

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