WO2022032479A1

WO2022032479A1 - Fingerprint recognition method and apparatus, and terminal device

Info

Publication number: WO2022032479A1
Application number: PCT/CN2020/108437
Authority: WO
Inventors: 胡泽望; 姚国峰; 沈健
Original assignee: 深圳市汇顶科技股份有限公司
Priority date: 2020-08-11
Filing date: 2020-08-11
Publication date: 2022-02-17

Abstract

A fingerprint recognition method and apparatus, and a terminal device (100). The terminal device (100) in the solution comprises a fingerprint recognition apparatus (10), the fingerprint recognition apparatus (10) comprises an optical image collection module (11), and the optical image collection module (11) comprises a pixel array. The fingerprint recognition method comprises: when it is detected that a finger of a user touches a fingerprint recognition area (115) of a terminal device (100), collecting multiple optical signals of a preset feature area in a pixel array by means of multiple instances of exposure (S101); according to the multiple optical signals of the preset feature area, determining whether the finger of the user covers the preset feature area (S102); if the finger of the user covers the preset feature area, collecting and acquiring a fingerprint image (S103); and verifying the identity of the user according to the fingerprint image (S104). Detection of optical signals of a preset feature area is performed to determine whether a finger of a user covers the preset feature area, and after the finger of the user covers the preset feature area, fingerprint image verification is performed, so that the problem of fingerprint failure or direct rejection caused by the fact that a finger of a user is not placed at a right position is avoided, and the false rejection rate of fingerprint recognition is thus reduced.

Description

Fingerprint identification method, device and terminal device

technical field

The present application relates to the technical field of fingerprint identification, and in particular, to a fingerprint identification method, device and terminal device.

Background technique

With the development of electronic technology and the gradual increase in the importance of information security, the security verification mechanism with biometric identification is more and more widely used in terminal equipment. Fingerprint recognition is one of the more effective and commonly used types. For terminal devices with a display screen, users expect a high screen-to-body ratio, and the under-screen optical fingerprint recognition solution can meet the two requirements of information security and high screen-to-body ratio at the same time.

In the prior art, when using the optical principle for fingerprint identification, the valleys and ridges of the finger have different reflectivity to the light incident on the finger, which can form a fingerprint pattern with light and dark contrast, and the feature information of the fingerprint image is extracted and compared. Fingerprint recognition is possible. However, in the current design of terminal equipment, all screens are used as display screens, and an area of the screen is used as a fingerprint recognition area. During the application process, when the finger pressing position does not cover the fingerprint recognition area or only covers part of the area , the acquired fingerprint image has less fingerprint feature information or even no finger feature information can be obtained. When the finger only covers part of the fingerprint recognition area, the light existing in the environment easily passes through the edge of the finger, and enters the optical image acquisition module of the fingerprint recognition module through the screen, which will cause the signal-to-noise ratio of the fingerprint image to decrease.

However, in the above-mentioned fingerprint identification solution, the terminal device will still perform fingerprint identification according to the normal process in the above-mentioned situations, which may easily lead to identification failure and increase the authenticity rejection rate.

SUMMARY OF THE INVENTION

The present application provides a fingerprint identification method, device and terminal device, which are used to solve the problems of easy identification failure and high rejection rate in the existing fingerprint identification scheme, ensure the accuracy of fingerprint identification, and avoid the problems caused by invalid pressing. High rejection rate.

In a first aspect, an embodiment of the present application provides a fingerprint identification method, which is applied to a terminal device. The terminal device includes a fingerprint identification device, and the fingerprint identification device includes an optical image acquisition module, and the optical image acquisition module includes a pixel array. , the method includes:

When detecting that the user's finger touches the fingerprint recognition area of the terminal device, collect multiple optical signals of the preset feature area in the pixel array through multiple exposures;

determining whether the user's finger covers the preset characteristic area according to a plurality of optical signals of the preset characteristic area;

If the user's finger covers the preset feature area, collecting a fingerprint image;

The identity of the user is verified based on the fingerprint image.

In a specific embodiment, the method further includes:

If the user's finger does not cover the preset feature area, prompt information is pushed, and the prompt information is used to prompt the user to reposition the finger, or the fingerprint recognition fails, or the fingerprint recognition process ends.

In a specific implementation manner, when it is detected that the user's finger touches the fingerprint recognition area of the terminal device, before collecting multiple optical signals of the preset feature area in the pixel array through multiple exposures, the Methods also include:

Obtain the current security level of fingerprint identification performed by the terminal device;

The preset feature area is determined from the preset at least one feature area according to the security level.

In a specific implementation manner, the collecting multiple signals of the preset feature area in the pixel array by multiple exposures includes:

The short exposure signal collection is performed for a preset number of times in the preset characteristic area with a first preset exposure time, so as to obtain a plurality of optical signals in the preset characteristic area.

In a specific implementation manner, the pixels in the preset characteristic area acquire the plurality of optical signals in a pixel stacking manner.

In a specific implementation manner, the determining whether the user's finger covers the preset feature region according to multiple light signals of the preset feature region includes:

According to the collected multiple optical signals of the preset feature area, a coefficient of variation of the optical signal intensity in the preset feature area is obtained, where the coefficient of variation is used to represent the intensity of the optical signal in the preset feature area degree of change;

If the coefficient of variation is greater than a preset coefficient of variation threshold, it is determined that the user's finger covers the preset feature area;

Otherwise, it is determined that the user's finger does not cover the preset feature area.

In a specific embodiment, the method further includes:

obtaining an ambient light signal where the terminal device is located;

The coefficient of variation threshold is determined according to the intensity of the ambient light signal.

In a specific implementation manner, the determining of the coefficient of variation threshold according to the intensity of the ambient light signal includes:

obtaining the coefficient of variation threshold corresponding to the intensity of the ambient light signal according to the preconfigured correspondence between the intensity of the ambient light signal and the threshold of the coefficient of variation;

or,

obtaining the difference between the intensity of the ambient light signal and the standard ambient light intensity according to the preset standard ambient light intensity and the standard variation coefficient threshold;

The threshold change value corresponding to the difference is increased or decreased on the standard coefficient of variation threshold to obtain the coefficient of variation threshold.

acquiring a first optical signal with the largest signal intensity and a second optical signal with the smallest signal intensity among the multiple optical signals collected in the preset characteristic area;

Whether the user's finger covers the preset feature area is determined according to the ratio of the decrease in the signal strength of the second optical signal compared to the first optical signal and a preset ratio.

In a specific implementation manner, if the excitation light source used in collecting the optical signal is an infrared light source, the determination of the intensity reduction ratio of the second optical signal compared with that of the first optical signal and a preset ratio is performed. Whether the user's finger covers the preset feature area, including:

If the ratio of the intensity reduction of the second optical signal compared to the first optical signal exceeds the preset ratio, and the appearance time of the first optical signal is later than the appearance time of the second optical signal, then determining that the user's finger covers the preset feature area;

In a specific implementation manner, if the excitation light source used when collecting the optical signal is visible light emitted by the screen of the terminal device, the ratio according to the decrease in the intensity of the second optical signal compared to the first optical signal and a preset ratio to determine whether the user's finger covers the preset feature area, including:

If the ratio of the intensity reduction of the second optical signal compared to the first optical signal exceeds the preset ratio, and the appearance time of the first optical signal is earlier than the appearance time of the second optical signal, then determining that the user's finger covers the preset feature area;

In a specific embodiment, the method further includes:

obtaining an ambient light signal where the terminal device is located;

The preset ratio is determined according to the intensity of the ambient light signal.

In a specific implementation manner, the determining the preset ratio according to the intensity of the ambient light signal includes:

obtaining the preset ratio corresponding to the intensity of the ambient light signal according to the preconfigured correspondence between the intensity of the ambient light signal and the ratio of the intensity change;

or,

obtaining the difference between the intensity of the ambient light signal and the standard ambient light intensity according to the preset standard ambient light intensity and the standard ratio of the intensity change;

The ratio change value corresponding to the difference value is increased or decreased from the standard ratio to obtain the preset ratio.

In a specific implementation manner, after determining that the user's finger covers the preset feature area, the method further includes:

determining whether the user's finger is a living body according to a plurality of light signals in the preset feature area and preset living body judgment conditions;

If the plurality of optical signals in the preset feature area satisfy the living body judgment condition, determining that the user's finger is a living body;

Otherwise, the user's finger is non-living;

Wherein, the living body judgment conditions include:

None of the last three optical signals collected in the plurality of optical signals is a second optical signal, and the second optical signal is an optical signal with the lowest signal intensity among the plurality of optical signals;

coefficients of variation of all optical signals following the second optical signal in the plurality of optical signals are greater than a first preset threshold;

The increase of the signal intensity of the optical signal detected last time among the plurality of optical signals compared with the signal intensity of the second optical signal is greater than a second preset threshold.

In a second aspect, an embodiment of the present application provides a fingerprint identification device, the fingerprint identification device includes an optical image acquisition module, the optical image acquisition module includes a pixel array, and the device further includes:

The optical image acquisition module is configured to collect a plurality of optical signals of a preset feature area in the pixel array through multiple exposures when it is detected that the user's finger touches the fingerprint identification area of the fingerprint identification device;

a processing module, configured to determine whether the user's finger covers the preset feature region according to a plurality of optical signals in the preset feature region;

The optical image acquisition module is further configured to acquire a fingerprint image if the user's finger covers the preset feature area;

The processing module is further configured to verify the identity of the user according to the fingerprint image.

In a specific implementation manner, the device further includes: a display module, and the processing module is further configured to push prompt information through the display module if the user's finger does not cover the preset feature area, and the The prompt information is used to prompt the user to reposition the finger, or the fingerprint recognition fails, or to end the fingerprint recognition process.

In a specific embodiment, the processing module is further used for:

Obtain the security level of the fingerprint identification device currently performing fingerprint identification;

In a specific embodiment, the optical image acquisition module is specifically used for:

In a specific implementation manner, the optical image acquisition module is specifically configured to acquire the plurality of optical signals for the pixels in the preset characteristic area in a pixel superposition manner.

In a specific embodiment, the processing module is specifically used for:

In a specific embodiment, the processing module is further used for:

acquiring an ambient light signal where the fingerprint identification device is located;

In a specific embodiment, the processing module is specifically used for:

or,

In a specific embodiment, the processing module is specifically used for:

In a specific embodiment, if the excitation light source used when collecting the optical signal is an infrared light source, the processing module is specifically used for:

In a specific implementation manner, if the excitation light source used when collecting the optical signal is the visible light emitted by the screen of the terminal device, the processing module is specifically configured to:

In a specific embodiment, the processing module is further used for:

In a specific embodiment, the processing module is specifically used for:

or,

In a specific embodiment, the processing module is further used for:

Otherwise, the user's finger is non-living;

Wherein, the living body judgment conditions include:

The increase of the signal intensity of the last detected optical signal among the plurality of optical signals compared with the signal intensity of the second optical signal is greater than a second preset threshold.

In a third aspect, an embodiment of the present application provides a terminal device, including:

Processor, memory, display screen, touch control module, and fingerprint identification device;

the memory is used to store computer programs;

The fingerprint identification device includes an optical image acquisition module, and the optical image acquisition module includes a pixel array;

The processor executes the computer program stored in the memory, so that the terminal device executes the fingerprint identification method described in any one of the first face-to-face.

Optionally, a color filter is provided in the pixel array, and the wavelength band range through which the color filter passes includes a wavelength band used for fingerprint identification.

In a fourth aspect, an embodiment of the present application provides a storage medium, including: a readable storage medium and a computer program, where the computer program is stored in the readable storage medium, and the computer program is used to implement any one of the first aspect The fingerprint identification method described in item.

In the fingerprint identification method, device, and terminal device provided by the embodiments of the present application, the terminal device in this solution includes a fingerprint identification device, and the fingerprint identification device includes an optical image acquisition module, and the optical image acquisition module includes a pixel array. When reaching the fingerprint identification area of the terminal device, multiple optical signals of the preset feature area in the pixel array are collected through multiple exposures. Determine whether the user's finger covers the preset feature area according to multiple optical signals in the preset feature area. If the user's finger covers the preset feature area, a fingerprint image is collected and obtained, and the user's identity is verified according to the fingerprint image. If the user's finger does not cover the preset feature area If the feature area is set, a prompt message will be pushed to prompt the user to reposition the finger or end the fingerprint identification process. Through the detection of the optical signal of the preset feature area, it is determined that the user's finger covers the preset feature area, and the fingerprint image verification is performed after the coverage is completed. The problem of fingerprint failure or direct rejection caused by fingerprint identification reduces the rejection rate of fingerprint identification.

Description of drawings

FIG. 1 is a schematic diagram of a front structure of a terminal device provided by an embodiment of the present application;

2 is a schematic diagram of a partial cross-sectional structure of a terminal device along A-A' provided by an embodiment of the present application;

FIG. 3 is a schematic diagram of a fingerprint identification scenario provided by an embodiment of the present application;

4 is a schematic diagram of a fingerprint image collected during fingerprint identification according to an embodiment of the present application;

FIG. 5 is a schematic diagram of the composition and structure of a terminal device according to an embodiment of the present application;

FIG. 6 is a schematic flowchart of Embodiment 1 of the fingerprint identification method provided by the embodiment of the present application;

FIG. 7 is a schematic flowchart of Embodiment 2 of the fingerprint identification method provided by the embodiment of the present application;

8 is a schematic diagram of a preset feature area provided by an embodiment of the present application;

FIG. 9 is a schematic diagram of the signal strength of an optical signal according to an embodiment of the present application;

Fig. 10 is the working state schematic diagram of the terminal device fingerprint identification module that changes with time provided by the embodiment of the application;

FIG. 11 is a schematic flowchart of Embodiment 3 of the fingerprint identification method provided by the embodiment of the present application;

12 is a schematic diagram of a pixel array of an optical image collection module provided by an embodiment of the present application;

FIG. 13 is a schematic diagram of an optical signal intensity change provided by an embodiment of the present application;

FIG. 14 is a schematic structural diagram of Embodiment 1 of a fingerprint identification device provided by an embodiment of the present application;

FIG. 15 is a schematic structural diagram of Embodiment 2 of a fingerprint identification device provided by an embodiment of the present application;

FIG. 16 is a schematic structural diagram of a terminal device provided by an embodiment of the present application.

detailed description

In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments It is a part of the embodiments of the present application, but not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

With the development of electronic technology and the user's attention to information security, the mechanism of identifying and verifying the user's biometric features is widely used in terminal devices, and fingerprint recognition is a relatively common type. In the current process of fingerprint recognition using optical principles, when the user's finger does not cover the fingerprint recognition area or covers a small area, the terminal device will also perform fingerprint recognition according to the normal process, which may easily lead to fingerprint recognition failure and rejection of authenticity. rate increased.

In view of the problems existing in the prior art, the embodiments of the present application provide a fingerprint identification method, which can quickly determine whether a user's finger will cover certain characteristic areas of the image sensor, such as the central area of the fingerprint identification area, so as to ensure that the fingerprints obtained subsequently The image can have enough feature information and high enough signal-to-noise ratio.

The main idea of this solution is to set several fixed characteristic areas in the fingerprint recognition area by means of software or hardware. The fingerprint image recognition process is carried out in the follow-up time, so as to avoid the direct recognition failure due to the inappropriate position of the user's finger, which can ensure that the fingerprint image has sufficient feature information and signal-to-noise ratio, and avoid the problem of increasing the false rejection rate caused by invalid pressing.

The fingerprint identification method provided by the embodiment of the present application can be mainly applied to the field of optical fingerprint identification. Further, it can be applied to various terminal devices using optical fingerprint identification, such as mobile computing devices such as smart phones, notebook computers, tablet computers, game devices, etc., as well as electronic databases, automobiles, and bank automatic teller machines (automated teller machine, ATM). and other terminal devices that require fingerprint identification.

Fig. 1 is a schematic diagram of a front structure of a terminal device provided by an embodiment of the present application, and Fig. 2 is a schematic diagram of a partial cross-sectional structure of a terminal device provided by an embodiment of the present application along A-A'. As shown in FIG. 1 , on the front of a commonly used terminal device 100 (such as a mobile phone), a display screen 110 is included, and a fingerprint identification area 115 for fingerprint identification is provided therein. When the user's finger 140 touches the fingerprint identification area 115, fingerprint identification is performed. Process, if shown in 2, the figure shows that the valley 142 and ridge 141 of the finger reflect the light 150 incident on the finger, and the reflected light 151 passes through the display screen 150 and enters the pixels 122 in the pixel array 121, which can form a band There are fingerprint patterns with light and dark degrees, and the terminal device performs fingerprint identification through the acquired fingerprint patterns.

In the implementation of the fingerprint identification solution provided by the present application, the display screen 150 or other layers at least have a touch control function in the fingerprint identification area 115 for judging whether the pressing finger touches the fingerprint identification area 115, and the touch control Functions may be implemented by capacitive touch control or resistive touch control or pressure sensitive touch control, including but not limited to.

FIG. 3 is a schematic diagram of a fingerprint recognition scenario provided by an embodiment of the present application. As shown in FIG. 3 , during the fingerprint recognition process, the alignment quality of the user's finger pressing position and the position of the fingerprint recognition area will affect the fingerprint obtained by the image acquisition module. images are affected. The situation shown in (a) on the left side of FIG. 3 is a situation in which the pressing position of the finger 140 and the fingerprint recognition area 115 are well aligned. The situation shown in (b) on the left side of FIG. 3 is a situation in which the alignment quality between the finger pressing position and the fingerprint recognition area is poor.

FIG. 4 is a schematic diagram of a fingerprint image collected during fingerprint identification according to an embodiment of the present application. As shown in FIG. 3 above, the fingerprint image collected by the optical image collection module in the two cases is shown in FIG. 4 . When the alignment quality between the pressing position of the finger 140 and the fingerprint recognition area 115 is good, in the fingerprint image obtained by the optical image acquisition module, the area with fingerprint information occupies a larger area of the entire image, and more feature information can be extracted. . On the contrary, when the alignment quality between the pressing position of the finger 140 and the fingerprint identification area 115 is poor, in the collected image, the area with fingerprint information occupies a smaller proportion of the entire image area, and less feature information can be extracted.

FIG. 5 is a schematic diagram of the composition and structure of a terminal device provided by an embodiment of the present application. Based on the situations shown in FIG. 3 and FIG. 4 above, the fingerprint identification solution proposed by the present application uses a shorter The exposure time quickly collects the light signals collected by the pixels in the characteristic area (images are not collected in this process), and further analyzes the signal changes to determine whether the user's finger covers the characteristic area, which can be one or more. For example, some pixels at the center of the pixel array may be selected as feature regions. When the finger covers the center of the fingerprint recognition area, the finger image collected by the optical image acquisition module for a long time exposure can ensure that the fingerprint information can cover the middle area of the fingerprint acquisition image, ensure that the fingerprint information accounts for a large proportion of the entire image, and can extract enough information. feature point information. Based on this idea, as shown in FIG. 5 , the terminal device to which the fingerprint identification method provided by the present application is applied at least needs to include: a touch control module, an excitation light source, an optical image acquisition module and a signal processing module.

In an implementation of the solution, it should be understood that the pixels of a feature area may be consecutive adjacent pixels of m rows and n columns, where m and n are both positive integers greater than or equal to 1. For different feature regions, the number of rows and columns of pixels may be different or the same, which is not limited in this solution.

The fingerprint identification method provided by the present application will be described in detail below through several specific embodiments.

FIG. 6 is a schematic flowchart of Embodiment 1 of the fingerprint identification method provided by the embodiment of the present application. As shown in FIG. 6 , the fingerprint identification method specifically includes the following steps:

S101: When it is detected that the user's finger touches the fingerprint identification area of the terminal device, collect multiple optical signals of the preset feature area in the pixel array through multiple exposures.

In this step, during the running process of the terminal device, in scenarios such as unlocking, payment, and login of some application programs, the user's identity can be verified by means of fingerprint recognition. In these cases, the terminal device will detect the user's touch operation. After detecting that the user's finger touches the fingerprint recognition area of the terminal device, the terminal device collects multiple optical signals at the preset feature area through multiple exposures in a short period of time. The multiple exposure collection here is only collected at the preset feature area, and it is not necessary to collect the entire fingerprint identification area.

During the optical signal collection process for the preset characteristic area, the pixels in the preset characteristic area may be subjected to signal collection in a pixel stacking manner to acquire multiple optical signals. For the pixels in the same feature area, the optical signal can be collected by partial pixel stacking (Binning) or all pixels stacking, so as to improve the signal intensity.

In the specific implementation of the solution, it should be understood that the preset characteristic area here may be one or more characteristic areas. In the design process of the terminal device, the area in the fingerprint identification area is marked, and multiple characteristic areas are marked, so that the detection of the characteristic area can be used to determine whether to perform the fingerprint identification process in the future before fingerprint identification.

In a specific implementation manner, the optical signals of which characteristic areas are acquired is related to the security level of the terminal device currently performing fingerprint identification. For example, for the unlocking scene of the terminal device, one or two characteristic areas can be set for detection. ; But for payment scenarios, the security level is higher, so four or five more feature areas can be set for detection. Different scenarios or different security levels can be pre-configured with characteristic areas to be detected, that is, the above-mentioned preset characteristic areas.

S102: Determine whether the user's finger covers the preset characteristic area according to the plurality of light signals in the preset characteristic area.

In this step, the terminal device may determine whether the user's finger covers the preset feature region by analyzing the features such as the intensity change of the light signal according to the plurality of optical signals detected from the preset feature region.

In the specific implementation of the fingerprint identification method, whether the user's finger covers the preset feature area can be determined at least in the following ways:

The first way is to obtain a coefficient of variation of the optical signal intensity in the preset feature area according to the collected optical signals in the preset feature area, where the coefficient of variation is used to represent the preset feature The degree of variation in the intensity of the light signal in the area. If the coefficient of variation is greater than a preset coefficient of variation threshold, it is determined that the user's finger covers the preset feature area; otherwise, it is determined that the user's finger does not cover the preset feature area.

In this solution, it should be understood that the coefficient of variation threshold can be adjusted, and the threshold of the coefficient of variation is different in different environments where the terminal equipment is located. When the ambient light signal strength is higher, the coefficient of variation threshold can be set larger; when the ambient light signal strength is lower, the coefficient of variation threshold can be set smaller. Specifically, the coefficient of variation threshold may be determined according to the intensity of the ambient light signal. For example, in one manner, the coefficient of variation threshold corresponding to the intensity of the ambient light signal is acquired according to a preconfigured correspondence between the intensity of the ambient light signal and the threshold of the coefficient of variation. In another manner, the difference between the intensity of the ambient light signal and the standard ambient light intensity is obtained according to a preset standard ambient light intensity and a standard coefficient of variation threshold, and then increases or decreases on the standard coefficient of variation threshold The threshold change value corresponding to the difference value is used to obtain the coefficient of variation threshold. That is to say, the coefficient of variation threshold can be either a fixed data or data that changes with the intensity of the ambient light, and the specific determination method is not limited in this solution.

The coefficient of variation threshold is positively or negatively correlated with the intensity of ambient light.

The second method is to acquire a first optical signal with the largest signal intensity and a second optical signal with the smallest signal intensity among the multiple optical signals collected in the preset characteristic area; The ratio and the preset ratio of the first optical signal signal strength reduction are determined to determine whether the user's finger covers the preset feature area.

In this manner, there are certain differences in the specific process of determining that the user's finger covers the preset feature area due to different excitation light sources. When the excitation light source is an infrared light source, as the contact area of the user's finger on the terminal device increases, the infrared light signal gradually becomes stronger, that is to say, the first light signal appears later than the second light signal, and at the same time If the ratio of the intensity reduction of the second optical signal compared to the first optical signal exceeds the preset ratio, it can be determined that the user's finger covers the preset feature area, otherwise it is determined that the user's finger does not cover the preset feature area.

When the excitation light source is the visible light emitted by the screen, as the contact area of the user's finger on the terminal device increases, the light signal reflected by the user's finger gradually becomes weaker, that is to say, the first light signal appears earlier than the second light signal. It can be determined that the user's finger covers the preset feature area, otherwise it is determined that the user's finger does not cover the preset feature area.

Similarly, in this solution, the preset ratio for determining the intensity of the optical signal reduction is also related to the environment where the terminal device is located, so the preset ratio can be determined in advance according to the environment where the terminal device is located. Specifically, the preset ratio is determined according to the acquired ambient light signal of the terminal device. Specifically, the preset ratio may be determined according to the intensity of the ambient light signal. For example, in one manner, the preset ratio corresponding to the intensity of the ambient light signal may be acquired according to the preconfigured correspondence between the intensity of the ambient light signal and the ratio of the intensity change. In another manner, the difference between the intensity of the ambient light signal and the standard ambient light intensity is acquired according to a preset standard ambient light intensity and a standard ratio of intensity change. Then, the ratio change value corresponding to the difference value is increased or decreased on the standard ratio to obtain the preset ratio. That is to say, the preset ratio can be either fixed data or data that changes with the intensity of ambient light, and the specific determination method is not limited in this solution.

S103: If the user's finger covers the preset feature area, collect and acquire a fingerprint image.

S104: Verify the identity of the user according to the fingerprint image.

In the above two steps, after the terminal device determines that the user's finger covers the preset feature area, the pixel array collects an image of the fingerprint recognition area with a long exposure time to obtain a fingerprint image. According to the comparison between the fingerprint image and the authorized feature information, if the fingerprint image matches the feature information, it is determined that the fingerprint authentication is successful, and if the fingerprint image does not match the feature information, it is determined that the fingerprint authentication fails.

In this solution, if the user's finger does not cover the preset feature area, prompt information is pushed, and the prompt information is used to prompt the user to reposition the finger or end the fingerprint identification process. When the terminal device determines that the user's finger does not cover the preset feature area, it can determine that the user has not placed the finger in a suitable position, and the terminal device can remind the user to place the finger again, or remind the end of the fingerprint separation process without directly entering the verification process. .

The fingerprint identification method provided in this embodiment determines that the user's finger covers the preset feature area by detecting the optical signal of the preset feature area, and then performs fingerprint image verification after coverage. If the user's finger is not placed in a suitable position, the fingerprint recognition fails or the fingerprint is directly rejected, which reduces the rejection rate of fingerprint recognition.

On the basis of the above embodiments, the following describes the solution of the fingerprint identification method provided by the present application in the specific application process through several specific examples.

FIG. 7 is a schematic flowchart of Embodiment 2 of the fingerprint identification method provided by the embodiment of the application. As shown in FIG. 7 , in this example, the screen of the device is an organic light-emitting diode (Organic Light-Emitting Diode, OLED) screen as an example, The fingerprint identification method specifically includes the following steps:

S201: Enter the fingerprint identification scene.

In this step, when entering a fingerprint recognition scenario such as mobile payment, the terminal device prompts the user to perform fingerprint recognition. The prompting method can be lighting on the screen fingerprint identification area of the terminal device; text prompting can be performed on the display screen, etc., including but not limited to this method.

S202: The touch screen detects that the finger touches the fingerprint recognition area, and triggers the start of fingerprint recognition.

In this step, when the user's finger touches the fingerprint recognition area, and the touch control module of the screen detects that the finger touches the surface of the fingerprint recognition area, the start of fingerprint recognition is triggered.

S203: The light-emitting unit of the fingerprint identification area in the display screen emits light.

Specifically, the light-emitting unit in the fingerprint identification area on the display screen emits light for performing coverage detection of the feature area.

S204: The characteristic area pixel collects multiple optical signals with a short exposure time for multiple times.

In this step, the terminal device collects short exposure signals for a preset number of times with a first preset exposure time in the preset characteristic area, to obtain a plurality of optical signals in the preset characteristic area. The first preset exposure time can be set according to actual requirements.

In a specific implementation of this step, the spacing between adjacent ridges of a human finger is about 500 μm. In order to avoid that the light signal collected by the short exposure time of the feature area only comes from the valley of the finger or only from the ridge of the finger, it is necessary to ensure that the light signal collected from the selected feature area includes both the signal from the valley and the signal from the ridge. For example, when the signal collected by the feature area only comes from the valley of the finger, the light emitted on the screen is reflected on the surface of the valley, and the difference between the signal and the signal when the finger does not cover the feature recognition area is small. Therefore, the information reflected in the preset feature area after passing through the optical system of the fingerprint identification module can cover a range of at least 500 μm in length and width on the finger. For example, in a fingerprint identification system with an imaging magnification ratio of 1:1 (isometric image), a characteristic area composed of a plurality of pixels at least includes a square area with a side length of 500 μm. In the fingerprint identification module with an imaging magnification ratio of 1:4 (reduced image), the characteristic area composed of multiple pixels includes at least a square area with a side length of 125 μm. In this embodiment, FIG. 8 is a schematic diagram of a preset feature area provided by this embodiment of the application. As shown in FIG. 8 , the overall area 122 of the pixel array of the optical image acquisition module 120 in the fingerprint identification module consists of 200 rows and 200 columns. It consists of 40,000 adjacent pixels, each of which is a square with a side length of 7 μm. In this solution, the preset feature area 123 consists of 400 adjacent pixels in 20 rows and 20 columns. The preset feature area is located in the center of the pixel array, and the center of the preset feature area coincides with the center of the pixel array. The optical system adopted in this embodiment can form an image of the object in the fingerprint identification area into an image that is reduced to 1/5 of the original object on the pixel array. Therefore, the signal collected in the characteristic area can reflect the information within the size range of the fingerprint identification area-700μm*700μm. The 400 pixels in the feature area are in the form of pixel stacking, and the signal is continuously collected for multiple times with a short exposure time t1, where t1 is less than 10ms; for example, t1 can be 1ms, because the pixel stacking method is adopted, and the feature area has fewer pixels , high-frequency sampling can be performed with a short exposure time, and a strong optical signal can be obtained at the same time.

S205: Multiple optical signals are compared with the model.

S206: Determine whether the user's finger covers the pixels of the feature area.

In the specific implementation of this step, the optical signal collected multiple times is compared with a known model (the model here refers to the intensity variation model of the optical signal) to determine whether the finger covers the characteristic area; the model can be Trained through a large number of scenarios. FIG. 9 is a schematic diagram of the signal intensity of an optical signal provided by an embodiment of the present application. As shown in FIG. 9 , in a certain scene, the signal intensity collected by five short exposures with an exposure time of 1 ms in the preset feature area is shown in FIG. 9 . Change, Fig. 9 (a) shows the change when the finger covers the preset feature area. After the finger presses the screen, the reflectivity of the upper ridge of the finger to light is lower than that when the finger is not pressed. Therefore, as time changes, when the user's finger finally covers the feature area, the signal intensity has a decreasing process. Two feasible models for judging whether the user's finger presses the feature area are provided as follows:

1. When the finger covers the feature area, due to the influence of the finger on the emission of light emitted by the screen, specifically, the finger presses the feature area, the light reflected to the feature area is reduced, and the intensity of the light signal collected by the feature area is weakened. When the finger does not cover the feature area, the signal change is smaller. Therefore, the coefficient of variation can be calculated by the optical signals collected five times in the preset characteristic area. When the coefficient of variation is greater than a certain threshold (that is, the threshold of the coefficient of variation preset in the foregoing embodiment), such as 10%, at this time, the optical signal collected in the characteristic area is greatly affected by the pressing of the finger, and it is considered that the finger is covered during the pressing process. feature area. When the coefficient of variation is lower than 10%, the finger is considered to not cover the characteristic area.

In addition, the light signal collected by the feature area includes ambient light from non-screen light sources in addition to the light reflected from the screen surface. The existence of external ambient light will affect the intensity of the optical signal collected in the characteristic area. The threshold can be adjusted through an ambient light sensor provided on the terminal device. For example, when the ambient light is dark, the change of the light signal is mainly affected by the finger, and the threshold value of the coefficient of variation can be reduced to 8%. When the outside light is strong and the finger has not pressed the feature area, the light signal collected by the feature area is stronger than the signal collected when the outside ambient light is dark. When the finger presses the feature area, the external ambient light will not enter the feature area due to the occlusion of the finger. In this case, the external ambient light has a large contribution to the coefficient of variation, so the judgment threshold can be increased. For example, when the intensity of ambient visible light is 10,000 Lux (Lux), the threshold of the coefficient of variation needs to be adjusted to 15%. When the calculated coefficient of variation is higher than 15%, the finger is considered to cover the characteristic area; otherwise, the finger is considered to not cover the characteristic area. To sum up, in a specific implementation of the solution, the terminal device may obtain the ambient light signal where the terminal device is located in advance, and determine the coefficient of variation threshold according to the intensity of the ambient light signal. In a common implementation manner, the intensity of the ambient light signal is proportional to the threshold value of the coefficient of variation.

In this solution, no matter how many preset characteristic areas there are, for each characteristic area, it can be determined whether the user's finger covers the characteristic area by comparing the coefficient of variation of the optical signal intensity with the threshold of the coefficient of variation according to the above method. .

2. Determine whether the user's finger covers the preset according to the ratio of the intensity reduction between the first optical signal with the largest signal intensity and the second optical signal with the smallest signal intensity among the multiple optical signals collected in the preset feature area feature area.

In a specific implementation manner, the highest intensity of the signals collected multiple times in the preset feature area for a short exposure time is I1 (that is, the intensity of the aforementioned first optical signal), and the lowest intensity is I2 (that is, the intensity of the aforementioned second optical signal). strength). When the ratio of I2 is lower than that of I1 exceeds a threshold (that is, the preset ratio referred to in the foregoing embodiment). For example, the threshold value can be 30%, and when the time when the lowest intensity appears is later than the time when the highest intensity appears, it is considered that the finger is pressing on the feature area; Some ambient light sensors adjust this threshold. For example, when the ambient visible light intensity is 10,000 Lux (Lux), this threshold needs to be increased to 30%. That is to say, the terminal device may obtain the ambient light signal in advance, and determine the preset ratio according to the intensity of the ambient light signal.

For comparison, (b) in FIG. 9 shows the change of signal intensity obtained by using a short exposure time of 1 ms when the user's finger does not effectively cover the feature area. When the finger is not covered, since the influence of the finger on the signal strength of the feature area is negligible, the variation of the signal received by the pixels in the feature area is small. Using the judgment methods of the above method 1 and method 2, it can be judged that the finger does not cover the characteristic area. The two solutions provided above are the solutions for judging whether the user's finger (fingerprint image) covers the feature area of the pixel array through a simplified model, and the actual model can be obtained by training a large number of scenarios.

S207: The pixel array acquires a fingerprint image with a long exposure time.

S208: Remind the user to reset the finger or terminate the fingerprint identification.

S209: fingerprint image feature information comparison.

S210: Whether the fingerprint image matches the feature information.

S211: The fingerprint authentication is successful.

S212: Fingerprint authentication fails.

In the above several steps, after it is determined that the user's finger covers the preset feature area in the pixel array, the entire pixel array acquires the user's fingerprint image with a longer exposure time t2, where t2 is greater than 4 times of t1, and t2 does not exceed 100ms (long exposure time). For example, t2 may be 40ms. Then, the characteristic information of the obtained fingerprint image is compared with the characteristic information of the stored authorized original fingerprint. When the feature information comparison is successful, it is determined that the fingerprint authentication is successful; when the feature information comparison fails, it is determined that the fingerprint authentication fails.

FIG. 10 is a schematic diagram of the working state of the fingerprint identification module of a terminal device provided by an embodiment of the application over time. As shown in FIG. 10 , it is a schematic diagram of the working state of the fingerprint identification module over time in a situation where a fingerprint covers a characteristic area. . When the touch signal is collected by the user's finger, the pixels in the preset feature area in the optical image collection module are triggered to start collecting the light signal with a short exposure time. After the signal processing module performs signal processing, it is judged that the user's finger covers the preset characteristic area, triggers a pixel array containing characteristic pixels to collect fingerprint images with a long exposure time, and judges whether the collected fingerprint image characteristic information matches to complete the fingerprint identification process.

However, if it is determined that the user's finger does not cover the pixel array feature area, the user's finger is not pressed in the correct position or the fingerprint recognition is terminated. For example, the determination method may be that the terminal prompts the user with text on the display screen "the finger is not pressed in the correct position, please press again".

In the implementation process of the whole scheme, since the short exposure time t1 used is significantly shorter than the long exposure time t2, the technical scheme of this embodiment can quickly and effectively determine whether the fingerprint image will cover the characteristic area of the pixel array. In this way, Before entering the fingerprint image collection and subsequent feature information comparison, it can determine whether the position of the user's finger is appropriate, and when the appropriate position is not covered, the user can be reminded to avoid the failure of fingerprint recognition due to the misplacement of the finger, and reduce rejection. sincere.

FIG. 11 is a schematic flowchart of the third embodiment of the fingerprint identification method provided by the embodiment of the application. As shown in FIG. 11 , in different application scenarios, verification of biometric information of different security levels is required, which can ensure a fast and safe terminal application. The fingerprint identification method specifically includes the following steps:

S301: Enter the fingerprint identification scene.

S302: Select the number and location of feature areas according to the security level of the scene.

S303: The touch screen detects that the finger touches the fingerprint recognition area, and triggers the start of fingerprint recognition.

In the above steps, in different application scenarios of the terminal device, verification of biometric information of different levels is required to ensure fast and safe terminal application. This embodiment exemplifies the possible selection and implementation of security levels in different security scenarios. For example, the security level required for payment by using a mobile phone is higher than the security level when the screen of the mobile phone is unlocked. When using fingerprint identification with a high security level, more fingerprint feature information may be required, so it is required that the fingerprint identification device can collect fingerprint images with sufficient feature information. For example, in the scenario of unlocking the mobile phone screen, the fingerprint image of the finger needs to have at least 13 matching feature points; in the scenario where the mobile phone performs large-amount payments, the fingerprint image obtained requires at least 15 matching feature points. The larger the number or range of the characteristic areas of the fingerprint recognition area covered by the finger, the more fingerprint information in the collected image can be guaranteed to cover more areas of the image, so that more feature point information can be extracted.

As described in the preceding steps, the terminal device determines and selects the number and/or location of the feature areas according to the scene security level of fingerprint identification.

S304: The light-emitting unit of the fingerprint identification area in the display screen emits light.

S305 : the pixels in the characteristic area collect multiple optical signals with a short exposure time for multiple times.

S306: Compare the multiple optical signals with the model.

S307: Determine whether the user's finger covers the pixels of the feature area.

In this embodiment, the terminal device uses a short exposure time to expose the pixels in the selected characteristic area to collect optical signals, and further judges whether the fingerprint image will cover the selected characteristic area in the scene. In different security level scenarios, the number and/or location of the feature areas is different. In short, in a higher security level scenario, the required number of feature areas is larger or has a larger range.

FIG. 12 is a schematic diagram of a pixel array of an optical image collection module provided by an embodiment of the present application. As shown in FIG. 12 , at a lower security level, for example, it may be a scenario of unlocking the screen of a mobile phone. 400 pixels in 123 are selected as the feature region, that is, one region is selected as the feature region (the selection position and size of the feature region in the first embodiment are the same). Under a higher security level, for example, in a mobile phone large-amount payment scenario, 400 pixels in each area of 124, 125, 126, and 127 are selected as the characteristic area, that is, the four areas are respectively used as the preset characteristic area. The center of the four feature areas is separated from the center of the pixel array by 80 pixels in the horizontal and vertical directions, respectively. The symmetry centers of the four feature regions coincide with the symmetry centers of the pixel array. The four preset feature regions are used to determine whether the finger covers the four feature regions, so as to ensure that the fingerprint image obtained in the final fingerprint identification has sufficient feature information and a high signal-to-noise ratio. When the

regions

124, 125, 126, and 127 are selected as the feature regions, the light signal changes obtained by the pixels in each region using a short exposure time are compared with the model separately to determine whether the finger covers each feature region. A finger is considered to cover the preset feature area when it is an area.

S308: The pixel array acquires a fingerprint image with a long exposure time.

S309: Remind the user to reset the finger or terminate the fingerprint identification.

S310 : fingerprint image feature information comparison.

S311: Whether the fingerprint image matches the feature information.

S312: The fingerprint authentication is successful.

S313: Fingerprint authentication fails.

The subsequent process is similar to that in the foregoing second embodiment.

In the fingerprint identification method provided in this embodiment, for fingerprint identification scenarios with different security levels, preset feature areas of different numbers and positions can be set, and the preset feature area can be detected before fingerprint authentication is performed, so that the user's finger can be judged. Whether the location is appropriate, whether it covers enough area to obtain the required feature information, and reminds the user when the appropriate location is not covered, improves the accuracy of fingerprint recognition, and avoids fingerprint recognition failure due to misplacement of the finger , reduce the rejection rate.

In the foregoing several examples, the process of fingerprint identification and detection is performed by using the light emitted by the screen of the terminal device itself as the excitation light source.

However, in the presence of a terminal device using an LCD screen, and the LCD screen is not transparent to visible light, this embodiment provides a new excitation light source. The excitation light source module used for fingerprint recognition in this solution is not the LCD display screen, and also It can be an infrared light source module with a wavelength of 940 nm located below the screen, that is to say, the excitation light source is an infrared light source. The process of the fingerprint identification method is similar to that shown in FIG. 7 . It should be pointed out that, in this embodiment, the optical signal collected by the image sensor comes from the infrared light scattered by the finger. At this time, the optical signal collected by the optical image collection module from the ridge of the finger is stronger than the signal from the valley of the finger. The opposite is the case in the embodiment shown in FIG. 7 . Therefore, the model for judging whether the user's finger will cover the characteristic area of the fingerprint identification module is different from the model in FIG. 7 . Compared with the embodiment shown in FIG. 7 , the two judgment models can be as follows:

1. Calculate the coefficient of variation of the optical signals collected multiple times with a short exposure time of the pixels in the characteristic area. When the coefficient of variation is greater than a certain threshold, such as 10%. At this time, the optical signal collected by the characteristic area is greatly affected by the finger pressing, and it can be considered that the finger covers the characteristic area during the pressing process. In addition, the light signal collected by the feature area includes not only the red light reflected from the finger, but also the external infrared light reflected from the non-finger. The presence of external light will affect the signal strength collected in the characteristic area, and the variation can be adjusted through the ambient light sensor on the terminal. For example, when the infrared light in the external environment is weak, the signal change is mainly affected by the finger. The threshold for the coefficient of variation can be raised to 12%. When the external light is strong and the finger does not press the preset feature area, the signal collected by the preset feature area comes from the external environment infrared light; when the finger presses the preset feature area, the external environment infrared light due to the finger The occlusion of less enters the preset feature area. In this case, the coefficient of variation of the signals collected for multiple times will be reduced due to the influence of ambient infrared light, and the threshold of the coefficient of variation can be lowered. For example, when the ambient infrared light intensity is 3000 Lux (Lux), the coefficient of variation threshold needs to be adjusted to 7%.

In the specific implementation of this solution, the terminal device can obtain the ambient light signal in advance, and then determine the coefficient of variation threshold according to the intensity of the ambient light signal; wherein, the intensity of the ambient light signal is related to the intensity of the ambient light signal. The coefficient of variation is proportional to the threshold size.

2. The highest intensity of the optical signal collected by the terminal device in the preset feature area for a short exposure time is I4 (the intensity of the first optical signal), and the lowest intensity is I5 (the intensity of the second optical signal). When I5 is lower than I4 by more than one When the threshold value (ie, the preset ratio) is set, and the time when the highest intensity appears is later than the time when the lowest intensity appears, it is considered that the finger is pressing on the characteristic area. For example, the threshold may be 40%. In addition, similar to that described in the previous comparison model, this threshold can be adjusted through the ambient infrared light sensor provided by the terminal. Specifically, when the ambient light intensity is strong, the threshold value needs to be lowered, and when the ambient infrared light intensity is weak, the preset ratio needs to be increased, that is, the threshold value at which the signal strength is reduced.

In different terminal devices, the models for judging whether the user's finger covers the preset feature area in the fingerprint recognition area are not necessarily the same, and the models can be updated according to changes in the terminal device.

Combining with the content of the foregoing embodiments, it can be seen that the excitation light source used when the terminal device collects the optical signal is an infrared light source, and the ratio of the intensity reduction of the second optical signal with the lowest intensity to the first optical signal with the highest intensity exceeds the preset ratio. and the appearance time of the first optical signal is later than the appearance time of the second optical signal, it can be determined that the user's finger covers the preset feature area; otherwise, it is determined that the user's finger does not cover the preset feature area. Set feature area.

However, when the excitation light source used by the terminal device to collect the optical signal is the visible light emitted by the screen of the terminal device, if the intensity of the second optical signal with the lowest intensity decreases compared to the first optical signal with the highest intensity by a ratio that exceeds the intensity reduction ratio of the second optical signal with the lowest intensity The preset ratio, and the appearance time of the first optical signal is earlier than the appearance time of the second optical signal, then it is determined that the user's finger covers the preset feature area; otherwise, it is determined that the user's finger does not cover the entire area. the preset feature area.

In the fingerprint identification method provided in this embodiment, for terminal devices that use LCD and other non-transparent natural light, the infrared light source can also be used as the excitation light source to quickly and effectively determine whether the fingerprint image will cover the characteristic area of the pixel array. Before entering the fingerprint image collection and subsequent feature information comparison, it can judge whether the position of the user's finger is appropriate, and when the appropriate position is not covered, the user can be reminded to avoid the failure of fingerprint recognition caused by the misplacement of the finger, and reduce the Refusal.

On the basis of any of the above-mentioned embodiments, in order to further ensure the safety of the terminal device during use, the embodiment of the present application also provides a method for determining whether the user's finger of the touch operation is a living body in a fingerprint identification process.

The solution for detecting whether the user's finger is a living body is described below by taking the case that the excitation light source in the terminal device is the visible light emitted by the screen of the terminal device.

When the user presses the screen, the pressure felt on the surface of the living finger continuously increases with the pressing, and the blood flow in the capillaries in the finger will flow to the edge of the pressing finger under the influence of the pressure. During this process, the absorption of non-red light by hemoglobin on the surface of the finger gradually weakens, and the color of the finger gradually changes from relatively reddish to relatively white. For non-living fingerprints, this process does not exist because there is no blood flow change. Therefore, this change can be used to identify whether the finger is a living body while determining whether the finger will cover the characteristic area of the optical image acquisition module.

In an implementation of the solution, in the optical image acquisition module of the terminal device, a color filter can be set for the pixels in the above-mentioned preset characteristic area, and the wavelength band range transmitted by the color filter includes the wavelength band used for fingerprint identification. Pixels in different feature regions may have the same or different color filters. Or different pixels in the same feature area may also have different color filters, which is not limited to this solution.

The main function of the color filter is to improve the signal-to-noise ratio of the optical signal. Taking this solution as an example, when the user's finger presses the screen, the hemoglobin on the surface of the finger gradually weakens the absorption of non-red light, that is, the absorption of blue and green light. The absorption of light is weakened. If the pixel in the characteristic area is provided with a blue or green color filter, the reflection of blue or green light will be enhanced in the process of gradually turning white during the pressing process of the finger.

Specifically, according to the model training, it is possible to determine the change of the characteristics of the living finger when fingerprint recognition is performed, obtain the living judgment condition, and configure the living judgment condition in the terminal device. In the process of fingerprint recognition, after the terminal device collects multiple optical signals in the preset feature area, it determines whether the user's finger is a living body. Specifically, if the collected optical signals of the preset feature area satisfy the living body judgment condition, it is determined that the user's finger is a living body; otherwise, the user's finger is a non-living body.

In a specific implementation, acquiring the judgment condition may include: none of the multiple optical signals (for example, three optical signals) collected last in the multiple optical signals are not the second optical signal, and the second optical signal is The optical signal with the lowest signal intensity among the plurality of optical signals; the coefficient of variation of all the optical signals after the second optical signal with the lowest signal intensity among the plurality of optical signals is greater than the first preset threshold; the plurality of optical signals The increase of the signal intensity of the last detected optical signal in the signal compared to the signal intensity of the second optical signal is greater than the second preset threshold.

In the specific implementation of this solution, for example, the terminal device in the embodiment shown in FIG. 7 may be used, and the positions and numbers of the selected feature areas are the same. In a certain scene, the short exposure time of the preset feature area in the pixel array is 0.5ms, and the signals are continuously collected 8 times. The intensity change of the obtained optical signal is shown in FIG. 13 . FIG. 13 provides an embodiment of the present application with a Schematic diagram of the change of light signal intensity. Wherein (a) in Fig. 13 shows the signal change acquired by the living finger. First, it is judged whether the finger covers the characteristic area through the judgment model in the first embodiment. After judging whether the finger is covering the feature area, it is further judged whether the finger is from a living finger. A criterion for judging whether a finger is from a living body is as follows:

1. The last three optical signals in the optical signals collected multiple times are not the lowest intensity signals;

2. Calculate the coefficient of variation for the lowest signal and subsequent optical signals. The coefficient of variation must be greater than a threshold. This threshold can be 8%. The specific value of the threshold can be set according to the actual situation.

3. Among the optical signals collected for multiple times, the increase of the last collected optical signal exceeds a certain threshold compared with the signal with the lowest intensity. This threshold can be 30%, and the specific value of the threshold can be set according to the actual situation;

The terminal device may determine that the user's finger is a living body when it is determined that the detected multiple optical signals of the preset feature area meet the above three conditions simultaneously, otherwise, it may determine that the finger is not a living body.

(b) in FIG. 13 shows the signal variation acquired by a non-living finger. Similar to the living fingerprint, the same judgment method as in the first embodiment can be used to judge that the finger covers the characteristic area. However, when the above-mentioned judgment model is used to further judge whether the finger is from a living body, the signals collected multiple times with a short exposure time do not satisfy the aforementioned three conditions. Accordingly, it can be determined that the fingerprint is a non-living fingerprint.

The fingerprint identification method provided in this embodiment not only can determine whether the user's finger covers the characteristic area to improve the unlocking efficiency through the methods provided by any of the foregoing embodiments, but also provides a method for determining whether the fingerprint is a living fingerprint, which can effectively improve the unlocking efficiency. The security level of fingerprint recognition.

FIG. 14 is a schematic structural diagram of Embodiment 1 of the fingerprint identification device provided by the embodiment of the application. As shown in FIG. 14 , the fingerprint identification device 10 includes an optical image acquisition module 11, and the optical image acquisition module 11 includes a pixel array. The device also includes:

The optical image acquisition module 11 is configured to collect a plurality of optical signals of a preset feature area in the pixel array through multiple exposures when it is detected that the user's finger touches the fingerprint identification area of the terminal device;

A processing module 12, for determining whether the user's finger covers the preset feature region according to a plurality of light signals of the preset feature region;

The optical image acquisition module 11 is further configured to acquire a fingerprint image if the user's finger covers the preset feature area;

The processing module 12 is further configured to verify the identity of the user according to the fingerprint image.

The fingerprint identification device 10 may be implemented as a terminal device, or may be a module in the terminal device. In this solution, it should be understood that the processing module 12 can implement the touch control module and signal processing shown in FIG. 5 in the foregoing embodiment. The functions that the module needs to implement are summarized here.

The fingerprint identification device provided in this embodiment can implement the technical solutions in any of the foregoing method embodiments. The implementation principle and technical effect are similar. The characteristic area is set in the pixel array by means of software. Set the detection of the light signal in the characteristic area, confirm that the user's finger covers the preset characteristic area, and then perform fingerprint image verification after covering, remind the user when it is not covered, and avoid fingerprinting when the user's finger is not placed in a suitable position. Identify the problems that lead to fingerprint failure or direct rejection, and reduce the rejection rate of fingerprint identification.

FIG. 15 is a schematic structural diagram of Embodiment 2 of the fingerprint identification device provided by the embodiment of the application. As shown in FIG. 15 , on the basis of the foregoing embodiment, the fingerprint identification device 10 further includes:

The display module 13, the processing module 12 is further configured to push the prompt information through the display module 13 if the user's finger does not cover the preset feature area, and the prompt information is used to prompt the user to reposition the finger position , or to end the fingerprinting process.

On the basis of the above embodiment shown in FIG. 14 or FIG. 15 , the processing module 12 is also used for:

Acquiring the security level of the fingerprint identification device 10 currently performing fingerprint identification;

Optionally, the optical image acquisition module 11 is specifically used for:

Optionally, the optical image acquisition module 11 is specifically configured to acquire the plurality of optical signals for the pixels in the preset feature area in a pixel stacking manner.

Optionally, the processing module 12 is specifically used for:

Optionally, the processing module 12 is also used for:

acquiring the ambient light signal where the fingerprint identification device 10 is located;

Optionally, the intensity of the ambient light signal is positively correlated or negatively correlated with the coefficient of variation threshold.

Optionally, the processing module 12 is specifically used for:

or,

Optionally, the processing module 12 is specifically used for:

Optionally, if the excitation light source used when collecting the optical signal is an infrared light source, the processing module 12 is specifically used for:

Optionally, if the excitation light source used when collecting the optical signal is the visible light emitted by the screen of the fingerprint identification device, the processing module 12 is specifically used for:

Optionally, the processing module 12 is also used for:

Optionally, the processing module 12 is specifically used for:

or,

Optionally, the processing module 12 is also used for:

Otherwise, the user's finger is non-living;

Wherein, the living body judgment conditions include:

In the specific implementation of any of the above embodiments, it should be understood that acquiring the ambient light signal by the processing module 12 means that the processing module 12 acquires the ambient light signal collected by the sensor for collecting ambient light. For example, the processing module 12 Receive the ambient light signal sent by the ambient light sensor.

The fingerprint identification device provided by any of the above embodiments is used to implement the technical solutions in the foregoing method embodiments, and the implementation principles and technical effects thereof are similar, and are not repeated here.

FIG. 16 is a schematic structural diagram of a terminal device provided by an embodiment of the present application. As shown in FIG. 16 , the terminal device 20 provided by this embodiment includes:

processor 21, memory 22, display screen 23, touch control module 24, and fingerprint identification device 25;

The memory 22 is used to store computer programs;

The fingerprint identification device 25 includes an optical image acquisition module, and the optical image acquisition module includes a pixel array;

The processor 21 executes the computer program stored in the memory 22, so that the terminal device executes the technical solutions provided in any of the foregoing method embodiments.

The above-mentioned components of the terminal device 10 may be connected through a bus. Optionally, a color filter is provided in the pixel array, and the wavelength band range through which the color filter passes includes a wavelength band used for fingerprint identification.

The memory 22 may be a separate storage unit, or may be a storage unit integrated in the processor 21 . The number of processors 21 is one or more.

In the above implementation of the terminal device 20, the memory and the processor are electrically connected directly or indirectly to realize data transmission or interaction, that is, the memory and the processor can be connected through an interface or integrated together. For example, these elements can be electrically connected to each other through one or more communication buses or signal lines, such as can be connected through a bus. The memory stores computer-executed instructions for implementing the data access control method, including at least one software function module that can be stored in the memory in the form of software or firmware, and the processor executes various software programs and modules by running the software programs and modules stored in the memory. Functional application and data processing.

The memory can be, but is not limited to, random access memory (Random Access Memory, referred to as: RAM), read-only memory (Read Only Memory, referred to as: ROM), programmable read-only memory (Programmable Read-Only Memory, referred to as: PROM) ), Erasable Programmable Read-Only Memory (EPROM, referred to as: EPROM), Electrically Erasable Read-Only Memory (Electric Erasable Programmable Read-Only Memory, referred to as: EEPROM), etc. The memory is used to store the program, and the processor executes the program after receiving the execution instruction. Further, the software programs and modules in the above-mentioned memory may also include an operating system, which may include various software components and/or drivers for managing system tasks (such as memory management, storage device control, power management, etc.), and may Intercommunicate with various hardware or software components to provide the operating environment for other software components.

The processor may be an integrated circuit chip with signal processing capability. The above-mentioned processor may be a general-purpose processor, including a central processing unit (Central Processing Unit, CPU for short), an image processor, etc., and may implement or execute the methods, steps, and logical block diagrams disclosed in the embodiments of the present application.

The present application further provides a storage medium, including: a readable storage medium and a computer program, where the computer program is stored in the readable storage medium, and the computer program is used to implement the technical solutions in any of the foregoing method embodiments .

It can be understood that, the various numbers and numbers involved in the embodiments of the present application are only for the convenience of description, and are not used to limit the scope of the embodiments of the present application. In the embodiments of the present application, the size of the sequence numbers of the above-mentioned processes does not imply the sequence of execution, and the execution sequence of each process should be determined by its functions and internal logic, and should not constitute the implementation process of the embodiments of the present application. any restrictions.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present application. Scope.

Claims

A fingerprint identification method, characterized in that it is applied to a terminal device, the terminal device includes a fingerprint identification device, the fingerprint identification device includes an optical image acquisition module, and the optical image acquisition module includes a pixel array, and the method includes :

When detecting that the user's finger touches the fingerprint recognition area of the terminal device, collect multiple optical signals of the preset feature area in the pixel array through multiple exposures;

determining whether the user's finger covers the preset characteristic area according to a plurality of optical signals of the preset characteristic area;

If the user's finger covers the preset feature area, collecting a fingerprint image;

The identity of the user is verified based on the fingerprint image.
The method according to claim 1, wherein the method further comprises:

If the user's finger does not cover the preset feature area, prompt information is pushed, and the prompt information is used to prompt the user to reposition the finger, or to end the fingerprint identification process.
The method according to claim 1, wherein when it is detected that the user's finger touches the fingerprint recognition area of the terminal device, collecting a plurality of lights in a preset feature area in the pixel array through multiple exposures Before the signal, the method further includes:

Obtain the current security level of fingerprint identification performed by the terminal device;

The preset feature area is determined from the preset at least one feature area according to the security level.
The method according to any one of claims 1 to 3, wherein the collecting a plurality of signals of a preset feature area in the pixel array by multiple exposures comprises:

The short exposure signal collection is performed for a preset number of times in the preset characteristic area with a first preset exposure time, so as to obtain a plurality of optical signals in the preset characteristic area.
The method according to claim 4, wherein the pixels in the preset characteristic area acquire the plurality of optical signals in a pixel stacking manner.
The method according to claim 4, wherein the determining whether the user's finger covers the preset characteristic area according to a plurality of optical signals in the preset characteristic area comprises:

According to the collected multiple optical signals of the preset feature area, a coefficient of variation of the optical signal intensity in the preset feature area is obtained, where the coefficient of variation is used to represent the intensity of the optical signal in the preset feature area degree of change;

If the coefficient of variation is greater than a preset coefficient of variation threshold, it is determined that the user's finger covers the preset feature area.
The method according to claim 6, wherein the method further comprises:

obtaining an ambient light signal where the terminal device is located;

The coefficient of variation threshold is determined according to the intensity of the ambient light signal.
The method according to claim 7, wherein the determining the coefficient of variation threshold according to the intensity of the ambient light signal comprises:

obtaining the coefficient of variation threshold corresponding to the intensity of the ambient light signal according to the preconfigured correspondence between the intensity of the ambient light signal and the threshold of the coefficient of variation;

or,

obtaining the difference between the intensity of the ambient light signal and the standard ambient light intensity according to the preset standard ambient light intensity and the standard variation coefficient threshold;

The threshold change value corresponding to the difference is increased or decreased on the standard coefficient of variation threshold to obtain the coefficient of variation threshold.
The method according to claim 4, wherein the determining whether the user's finger covers the preset characteristic area according to a plurality of optical signals in the preset characteristic area comprises:

acquiring a first optical signal with the largest signal intensity and a second optical signal with the smallest signal intensity among the multiple optical signals collected in the preset characteristic area;

Whether the user's finger covers the preset feature area is determined according to the ratio of the decrease in the signal strength of the second optical signal compared to the first optical signal and a preset ratio.
The method according to claim 9, wherein, if the excitation light source used when collecting the optical signal is an infrared light source, the method according to the ratio of the intensity reduction of the second optical signal compared with that of the first optical signal and the prediction Setting a scale to determine whether the user's finger covers the preset feature area, including:

If the ratio of the intensity reduction of the second optical signal compared to the first optical signal exceeds the preset ratio, and the appearance time of the first optical signal is later than the appearance time of the second optical signal, then It is determined that the user's finger covers the preset feature area.
The method according to claim 9, wherein if the excitation light source used when collecting the optical signal is visible light emitted by the screen of the terminal device, comparing the first optical signal according to the second optical signal The ratio of signal strength reduction and the preset ratio to determine whether the user's finger covers the preset feature area, including:

If the ratio of the intensity reduction of the second optical signal compared to the first optical signal exceeds the preset ratio, and the appearance time of the first optical signal is earlier than the appearance time of the second optical signal, then It is determined that the user's finger covers the preset feature area.
The method according to any one of claims 9 to 11, wherein the method further comprises:

obtaining an ambient light signal where the terminal device is located;

The preset ratio is determined according to the intensity of the ambient light signal.
The method according to claim 12, wherein the determining the preset ratio according to the intensity of the ambient light signal comprises:

obtaining the preset ratio corresponding to the intensity of the ambient light signal according to the preconfigured correspondence between the intensity of the ambient light signal and the ratio of the intensity change;

or,

obtaining the difference between the intensity of the ambient light signal and the standard ambient light intensity according to the preset standard ambient light intensity and the standard ratio of the intensity change;

The ratio change value corresponding to the difference value is increased or decreased from the standard ratio to obtain the preset ratio.
The method according to any one of claims 1 to 3, wherein after determining that the user's finger covers the preset feature area, the method further comprises:

determining whether the user's finger is a living body according to a plurality of light signals in the preset feature area and preset living body judgment conditions;

If the plurality of optical signals in the preset feature area satisfy the living body judgment condition, determining that the user's finger is a living body;

Otherwise, the user's finger is non-living;

Wherein, the living body judgment conditions include:

None of the last three optical signals collected in the plurality of optical signals is a second optical signal, and the second optical signal is an optical signal with the lowest signal intensity among the plurality of optical signals;

coefficients of variation of all optical signals following the second optical signal in the plurality of optical signals are greater than a first preset threshold;

The increase of the signal intensity of the optical signal detected last time among the plurality of optical signals compared with the signal intensity of the second optical signal is greater than a second preset threshold.
A fingerprint identification device, characterized in that the fingerprint identification device includes an optical image acquisition module, the optical image acquisition module includes a pixel array, and the device further includes:

The optical image acquisition module is configured to collect a plurality of optical signals of a preset feature area in the pixel array through multiple exposures when detecting that the user's finger touches the fingerprint identification area of the fingerprint identification device;

a processing module, configured to determine whether the user's finger covers the preset feature region according to a plurality of optical signals in the preset feature region;

The optical image acquisition module is further configured to acquire a fingerprint image if the user's finger covers the preset feature area;

The processing module is further configured to verify the identity of the user according to the fingerprint image.
The device according to claim 15, characterized in that, the device further comprises: a display module, and the processing module is further configured to, if the user's finger does not cover the preset feature area, push the message through the display module Prompt information, where the prompt information is used to prompt the user to reposition the finger, or to end the fingerprint identification process.
The apparatus according to claim 15, wherein the processing module is further configured to:

Obtain the security level of the fingerprint identification device currently performing fingerprint identification;

The preset feature area is determined from the preset at least one feature area according to the security level.
The device according to any one of claims 15 to 17, wherein the optical image acquisition module is specifically used for:

The short exposure signal collection is performed for a preset number of times in the preset characteristic area with a first preset exposure time, so as to obtain a plurality of optical signals in the preset characteristic area.
The device according to claim 18, wherein the optical image acquisition module is specifically configured to acquire the plurality of optical signals for pixels in the preset characteristic area in a pixel superposition manner.
The device according to claim 18, wherein the processing module is specifically configured to:

According to the collected multiple optical signals in the preset feature area, a coefficient of variation of the optical signal intensity in the preset feature area is obtained, where the coefficient of variation is used to represent the intensity of the optical signal in the preset feature area degree of change;

If the coefficient of variation is greater than a preset coefficient of variation threshold, it is determined that the user's finger covers the preset feature area;

Otherwise, it is determined that the user's finger does not cover the preset feature area.
The apparatus according to claim 20, wherein the processing module is further configured to:

acquiring the ambient light signal where the fingerprint identification device is located;

The coefficient of variation threshold is determined according to the intensity of the ambient light signal; wherein, the intensity of the ambient light signal is proportional to the threshold of the coefficient of variation.
The device according to claim 21, wherein the processing module is specifically configured to:

obtaining the coefficient of variation threshold corresponding to the intensity of the ambient light signal according to the preconfigured correspondence between the intensity of the ambient light signal and the threshold of the coefficient of variation;

or,

obtaining the difference between the intensity of the ambient light signal and the standard ambient light intensity according to the preset standard ambient light intensity and the standard variation coefficient threshold;

The threshold change value corresponding to the difference is increased or decreased on the standard coefficient of variation threshold to obtain the coefficient of variation threshold.
The device according to claim 18, wherein the processing module is specifically configured to:

acquiring a first optical signal with the largest signal intensity and a second optical signal with the smallest signal intensity among the multiple optical signals collected in the preset characteristic area;

Whether the user's finger covers the preset feature area is determined according to the ratio of the decrease in the signal strength of the second optical signal compared to the first optical signal and a preset ratio.
The device according to claim 23, wherein, if the excitation light source used when collecting the optical signal is an infrared light source, the processing module is specifically used for:

If the ratio of the intensity reduction of the second optical signal compared to the first optical signal exceeds the preset ratio, and the appearance time of the first optical signal is later than the appearance time of the second optical signal, then determining that the user's finger covers the preset feature area;

Otherwise, it is determined that the user's finger does not cover the preset feature area.
The device according to claim 23, wherein if the excitation light source used when collecting the optical signal is visible light emitted by the screen of the fingerprint identification device, the processing module is specifically used for:

If the ratio of the intensity reduction of the second optical signal compared to the first optical signal exceeds the preset ratio, and the appearance time of the first optical signal is earlier than the appearance time of the second optical signal, then determining that the user's finger covers the preset feature area;

Otherwise, it is determined that the user's finger does not cover the preset feature area.
The device according to any one of claims 23 to 25, wherein the processing module is further configured to:

acquiring an ambient light signal where the fingerprint identification device is located;

The preset ratio is determined according to the intensity of the ambient light signal.
The apparatus according to claim 26, wherein the processing module is specifically configured to:

obtaining the preset ratio corresponding to the intensity of the ambient light signal according to the preconfigured correspondence between the intensity of the ambient light signal and the ratio of the intensity change;

or,

obtaining the difference between the intensity of the ambient light signal and the standard ambient light intensity according to the preset standard ambient light intensity and the standard ratio of the intensity change;

The ratio change value corresponding to the difference value is increased or decreased from the standard ratio to obtain the preset ratio.
The device according to any one of claims 15 to 17, wherein the processing module is further configured to:

determining whether the user's finger is a living body according to a plurality of light signals in the preset characteristic area and a preset living body judgment condition;

If the plurality of optical signals in the preset feature area satisfy the living body judgment condition, determining that the user's finger is a living body;

Otherwise, the user's finger is non-living;

Wherein, the living body judgment conditions include:

None of the last three optical signals collected in the plurality of optical signals is a second optical signal, and the second optical signal is an optical signal with the lowest signal intensity among the plurality of optical signals;

coefficients of variation of all optical signals following the second optical signal in the plurality of optical signals are greater than a first preset threshold;

The increase of the signal intensity of the last detected optical signal among the plurality of optical signals compared to the signal intensity of the second optical signal is greater than a second preset threshold.
A terminal device, characterized in that it includes:

Processor, memory, display screen, touch control module, and fingerprint identification device;

the memory is used to store computer programs;

The fingerprint identification device includes an optical image acquisition module, and the optical image acquisition module includes a pixel array;

The processor executes the computer program stored in the memory, so that the terminal device executes the fingerprint identification method according to any one of claims 1 to 14.
The terminal device according to claim 29, wherein a color filter is provided in the pixel array, and a wavelength band range through which the color filter passes includes a wavelength band used for fingerprint identification.
A storage medium, comprising: a readable storage medium and a computer program, wherein the computer program is stored in the readable storage medium, and the computer program is used to implement any one of claims 1 to 14. fingerprint identification method.