Fingerprint recognition module, electronic device, fingerprint recognition method and device

Abstract

The present application provides a fingerprint recognition module, an electronic device, a fingerprint recognition method and a device. The fingerprint recognition module includes: an optical structure layer for transmitting the reflected light of the fingerprint on the display device; a photosensitive sensor array including a first photosensitive area and a second photosensitive area; the first photosensitive area is used to generate a first signal for fingerprint recognition according to the reflected light, and the second photosensitive area is used to generate a second signal for calculating the depth information of the fingerprint according to the reflected light, and the depth information is used for liveness recognition. In the embodiments of the present application, fingerprint recognition is realized by using the first photosensitive area, and liveness recognition is realized by detecting the height difference between the valleys and ridges of the fingerprint through the second photosensitive area. Liveness recognition and fingerprint recognition can be achieved, and the accuracy of liveness recognition can be improved, and real and fake fingers can be effectively distinguished.

Description

Technical Field

[0001] This application relates to the technical field of fingerprint recognition, and particularly to a fingerprint recognition module, an electronic device, a fingerprint recognition method and a device. Background Art

[0002] Currently, there are two types of screen fingerprint recognition technologies: optical detection and ultrasonic detection. Ultrasonic fingerprint detection has high accuracy and can identify real and fake fingers, but its cost is much higher than that of optical fingerprint recognition.

[0003] Currently, all optical fingerprint technologies use the different reflectivities of fingerprint valleys and ridges to light to achieve fingerprint acquisition. However, this method has the defect that it cannot effectively distinguish real and fake fingers. Summary of the Invention

[0004] The purpose of the embodiments of this application is to provide a fingerprint recognition module, an electronic device, a fingerprint recognition method and a device, which can simultaneously achieve living body recognition and fingerprint recognition.

[0005] In a first aspect, the embodiments of this application provide a fingerprint recognition module, which is used to be disposed under a display device and includes:

[0006] An optical structure layer, which is used to transmit the reflected light of the fingerprint on the display device;

[0007] A photosensitive sensor array, which includes a first photosensitive area and a second photosensitive area; the first photosensitive area is used to generate a first signal for fingerprint recognition according to the reflected light, and the second photosensitive area is used to generate a second signal for calculating the depth information of the fingerprint according to the reflected light, and the depth information is used for living body recognition.

[0008] The embodiments of this application can simultaneously achieve fingerprint recognition and living body recognition, and because the depth information of the fingerprint is used for living body recognition of the fingerprint, the accuracy of living body recognition can be improved.

[0009] Optionally, in the fingerprint recognition module of the embodiments of this application, the first photosensitive area is provided with a plurality of first photosensitive pixels, the second photosensitive area is provided with a plurality of second photosensitive pixels, and the area of each first photosensitive pixel in at least part of the first photosensitive pixels is larger than the area of each second photosensitive pixel.

[0010] In order to achieve living body recognition in the embodiments of this application, it should be ensured that the imaging interval distance between an adjacent group of valleys and ridges is greater than or equal to the width of four second photosensitive pixels. Therefore, the photosensitive sensor array for living body recognition needs high resolution, and the resolution of the first photosensitive area for fingerprint recognition is less than the resolution of the area for living body recognition, rather than all being uniformly high resolution. Therefore, the cost can be reduced.

[0011] Optionally, in the fingerprint recognition module described in the embodiments of the present application, the area of each second photosensitive pixel in at least some of the second photosensitive pixels is smaller than the area of each of the first photosensitive pixels.

[0012] In the embodiments of the present application, by increasing the area of the first photosensitive pixels, the number of the first photosensitive pixels can be reduced, thereby reducing the manufacturing cost of the first photosensitive pixels.

[0013] Optionally, in the fingerprint recognition module described in the embodiments of the present application, the area of each of the first photosensitive pixels is larger than the area of each of the second photosensitive pixels.

[0014] In the embodiments of the present application, by increasing the area of the first photosensitive pixels, the number of the first photosensitive pixels can be reduced, thereby reducing the manufacturing cost of the first photosensitive pixels.

[0015] Optionally, in the fingerprint recognition module described in the embodiments of the present application, the second photosensitive area is provided with a plurality of second photosensitive pixels, the second photosensitive pixels are rectangular, and the length of the short side of the second photosensitive pixels is less than or equal to β*p / 4, where β is the magnification of the optical structure layer and p is the empirical distance value between a pair of adjacent valleys and ridges of the fingerprint.

[0016] Optionally, in the fingerprint recognition module described in the embodiments of the present application, the second photosensitive pixels are square.

[0017] Optionally, in the fingerprint recognition module described in the embodiments of the present application, the depth information includes the depth information of the valleys of the fingerprint and / or the depth information of the ridges of the fingerprint.

[0018] Optionally, in the fingerprint recognition module described in the embodiments of the present application, the second photosensitive area includes a plurality of second photosensitive sub-areas, the optical structure layer includes a plurality of first optical elements, the plurality of first optical elements respectively correspond to the plurality of second photosensitive sub-areas, and each of the first optical elements is used to transmit the reflected light to the corresponding second photosensitive sub-area.

[0019] Optionally, in the fingerprint recognition module described in the embodiments of the present application, the second photosensitive sub-areas are rectangular; the second photosensitive sub-areas are provided with a plurality of second photosensitive pixels distributed in a matrix, and the number of rows and columns of the second photosensitive pixels in each of the second photosensitive sub-areas is greater than or equal to 4.

[0020] Optionally, in the fingerprint recognition module described in the embodiments of the present application, the second photosensitive area surrounds the first photosensitive area, or the second photosensitive area is disposed on one side or multiple sides of the first photosensitive area.

[0021] Optionally, in the fingerprint recognition module described in the embodiments of the present application, the first photosensitive area is rectangular, and the second photosensitive area is a hollow rectangle and is disposed around the first photosensitive area.

[0022] In a second aspect, an embodiment of the present application provides an electronic device, including the fingerprint recognition module described in any one of the above and a display device, and the fingerprint recognition module is disposed below the display device.

[0023] In a third aspect, an embodiment of the present application provides a fingerprint recognition method, which is applied to an electronic device, and the electronic device includes a fingerprint recognition module. The method includes:

[0024] Obtaining a second signal generated by the fingerprint recognition module according to the reflected light of the fingerprint to be measured;

[0025] Generating depth information of the fingerprint according to the second signal;

[0026] Performing fingerprint liveness recognition according to the depth information.

[0027] Optionally, in the fingerprint recognition method described in the embodiments of the present application, the depth information includes depth information of the valleys of the fingerprint and / or depth information of the ridges of the fingerprint.

[0028] Optionally, in the fingerprint recognition method described in the embodiments of the present application, the generating the depth information of the fingerprint according to the second signal includes:

[0029] Generating an image of the fingerprint according to the second signal;

[0030] Obtaining a first position signal of the ridge of the fingerprint imaged in the image through a first optical element and a second position signal of the ridge of the fingerprint imaged in the image through a second optical element;

[0031] Obtaining a third position signal of the valley of the fingerprint imaged in the image through a third optical element and a fourth position signal of the ridge of the fingerprint imaged in the image through a fourth optical element;

[0032] Generating depth information of the ridges of the fingerprint according to the first position signal and the second position signal;

[0033] Generating depth information of the valleys of the fingerprint according to the third position signal and the fourth position signal.

[0034] In a fourth aspect, an embodiment of the present application further provides a fingerprint recognition device, including:

[0035] An acquisition module, configured to acquire a second signal generated by the fingerprint recognition module sensing an image of the fingerprint to be measured;

[0036] A generation module, configured to generate depth information of the fingerprint according to the second signal;

[0037] An identification module, configured to perform fingerprint liveness identification according to the depth information. Description of the Drawings

[0038] To more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation of the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0039] Figure 1 It is a schematic diagram of the first structure of the fingerprint recognition module in some embodiments of the present application.

[0040] Figure 2 It is a schematic diagram of the second structure of the fingerprint recognition module in some embodiments of the present application.

[0041] Figure 3 It is a schematic diagram of the third structure of the fingerprint recognition module in some embodiments of the present application.

[0042] Figure 4 It is a schematic diagram of the structure of the photosensitive sensor array of a fingerprint recognition module in some embodiments of the present application.

[0043] Figure 5 It is a schematic diagram of the optical path when binocular ranging is used for the photosensitive sensor array of a fingerprint recognition module in some embodiments of the present application.

[0044] Figure 6 It is a flowchart of a fingerprint recognition method in some embodiments of the present application.

[0045] Figure 7 It is a schematic diagram of the structure of a fingerprint recognition device in some embodiments of the present application. Detailed Embodiments

[0046] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.

[0047] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "inner" and "outer" is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this application is usually placed when in use. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation on the present application. In addition, terms such as "first" and "second" are only used for distinguishing descriptions and cannot be construed as indicating or implying relative importance.

[0048] It should also be noted that unless otherwise clearly specified and defined, the terms "arranged" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0049] Please refer to Figure 1 , Figure 1 is a schematic structural diagram of a fingerprint recognition module in some embodiments of the present application. The fingerprint recognition module 20 is used to be arranged below the display device 10. The fingerprint recognition module 20 includes: an optical structure layer 201 for transmitting the reflected light of the fingerprint 100 on the display device 10; a photosensitive sensor array 202 including a first photosensitive area and a second photosensitive area; the first photosensitive area is used to generate a first signal for fingerprint recognition according to the reflected light, and the second photosensitive area is used to generate a second signal for calculating the depth information of the fingerprint according to the reflected light, and the depth information is used for liveness recognition.

[0050] In some embodiments, please refer to Figure 2 , in which the optical structure layer 201 may include an optical imaging layer 21 and a light-shielding layer 22. The light-shielding layer 22 is arranged on or above the photosensitive sensor array 202, and the optical imaging layer 21 is arranged on the light-shielding layer 22. The optical imaging layer 21 is used to transmit the reflected light of the finger on the upper surface of the display device 10. Among them, the optical imaging layer 21 is formed with a plurality of spaced optical elements 212, and the light-shielding layer 22 is provided with a plurality of light-passing holes 221. The plurality of light-passing holes 221 and the plurality of optical elements 212 are arranged in one-to-one correspondence and opposite to each other. The optical imaging layer 21 may be a microlens layer. Correspondingly, a plurality of microlens structures are arranged on the optical structure layer 20. Of course, it can be understood that the optical structure layer 201 can be replaced by other optical layers. For example, the optical structure layer 201 can be a collimating hole layer, and each optical element 212 is equivalent to a collimating hole on the collimating hole layer.

[0051] In some other embodiments, as Figure 3 shown, the optical structure layer 201 further includes a light-transmitting material layer 23. The light-transmitting material layer 23 is disposed on the photosensitive sensor array 202, and the light-shielding layer 22 is disposed on the light-transmitting material layer 23. The light-transmitting material layer 23 is used to fill the distance between the light-shielding layer and the photosensitive sensor array 202 based on the focal length of the optical element 212. Of course, the light-transmitting material layer 23 can also be arranged in other ways. It can be arranged on the upper surface of the light-shielding layer, or on the lower surface of the light-shielding layer, or light-transmitting material layers are arranged on both the upper surface and the lower surface of the light-shielding layer. Please continue to refer to Figure 3 , the photosensitive sensor array 202 has a photosensitive surface, and the photosensitive surface includes a first photosensitive area 202a and a second photosensitive area 202b; the first photosensitive area 202a is used to generate a first signal for fingerprint recognition according to the reflected light of the fingerprint. The second photosensitive area 202b is used to generate a second signal for calculating the depth information of the fingerprint according to the reflected light of the finger, and the depth information is used for liveness recognition. Among them, the fingerprint recognition and liveness recognition functions can be integrated in the photosensitive sensor array 202, or the fingerprint recognition and liveness recognition functions can be integrated in the chip of the electronic device.

[0052] In the embodiments of the present application, fingerprint recognition is realized by using the first photosensitive area, and the depth information of the valleys and ridges of the fingerprint is detected by the second photosensitive area to realize liveness recognition. Liveness recognition and fingerprint recognition can be realized simultaneously, and the accuracy of liveness recognition can be improved, and real and fake fingers can be effectively distinguished. Among them, the depth information may only include the depth information of the valleys of the fingerprint, or only include the depth information of the ridges of the fingerprint, or include both the depth information of the valleys and the depth information of the ridges of the fingerprint. For example, when the depth information only includes the depth information of the valleys of the fingerprint, a distance threshold can be set. The distance between the valleys of the fingerprint of a real finger and the photosensitive sensor array should be greater than the distance between the valleys of the fingerprint in the 2D picture and the photosensitive sensor array. Since the 2D picture is flat, the distance between the valleys of the fingerprint in the 2D picture and the upper surface of the display device is almost 0, and the distance threshold can be set as the distance between the upper surface of the display device and the photosensitive sensor array. When the detected distance corresponding to the depth information is greater than the distance threshold, it is determined that the fingerprint liveness recognition passes; when it is less than or equal to the distance threshold, the fingerprint liveness recognition fails.

[0053] For example, when the depth information only includes the depth information of the ridges of the fingerprint, a distance threshold can be set. Since the finger is elastic and makes more sufficient contact with the surface of the display device, the gap between the real finger and the upper surface of the display device should be smaller than the gap between the ridges of the fingerprint in the 2D image and the upper surface of the display device. Therefore, the distance between the ridges of the fingerprint of the real finger and the photosensitive sensor array should be smaller than the distance between the ridges of the fingerprint in the 2D image and the photosensitive sensor array. When the detected distance corresponding to the depth information is greater than the distance threshold, it is determined that the fingerprint liveness recognition fails; when it is less than or equal to the distance threshold, the fingerprint liveness recognition passes. Of course, the fingerprint liveness detection can also be realized according to the depth information of the valleys of the fingerprint and the depth information of the ridges. Specifically, the fingerprint liveness detection is performed according to the height difference between the valleys and ridges of the fingerprint.

[0054] Next, each component of the fingerprint recognition module 20 will be described in detail.

[0055] Specifically, the optical imaging layer 21 can be a single-layer lens structure or a multi-layer lens structure. In this embodiment, the optical imaging layer 21 is a single-layer lens structure. The optical imaging layer 21 includes a transparent material layer 211 and a plurality of optical elements 212 formed on the upper surface of the transparent material layer 211. The optical elements 212 and the transparent material layer 211 can be an integral structure, and the optical imaging layer 21 can be made of light-transmitting glass. The optical elements 212 can be imaging lenses. The plurality of optical elements 212 are arranged at intervals. Of course, the specific layout manner of the plurality of optical elements 212 should correspond to the arrangement of the first photosensitive region 202a and the second photosensitive region 202b of the photosensitive sensor array 202 below. Among them, the optical imaging layer 21 transmits the first reflected light of the valleys and ridges of the fingerprint 100 and the second reflected light of the valleys and ridges through the plurality of optical elements 212, so that the first reflected light and the second reflected light are transmitted to the photosensitive sensor array 202.

[0056] Among them, the plurality of optical elements 212 include a plurality of first optical elements and a plurality of second optical elements. The plurality of first optical elements correspond to the second photosensitive region 202b for imaging the valleys and ridges of the fingerprint on the second photosensitive region 202b according to the reflected light. The plurality of second optical elements correspond to the first photosensitive region 202a for imaging the valleys and ridges of the fingerprint on the first photosensitive region 202a according to the reflected light. Of course, the first signal includes a first photosensitive signal generated by sensing the reflected light of the valleys and ridges of the fingerprint. The second signal includes a second photosensitive signal generated by sensing the reflected signals of the valleys and ridges of the fingerprint. The electronic device can generate an image of the corresponding fingerprint based on the first photosensitive signal and the second photosensitive signal of the fingerprint, and then obtain the position signals corresponding to the valley image and the ridge image of the fingerprint according to the fingerprint image.

[0057] Of course, it can be understood that the optical imaging layer 21 should not be limited to lens imaging, and can also be an optical structure using the principle of pinhole imaging. For example, the optical element can be a pinhole for imaging.

[0058] Among them, the light-shielding layer 22 can be obtained by coating and patterning a light-shielding material on the lower surface of the optical imaging layer 21. Of course, it can be understood that the light-shielding layer 22 can also be formed by coating on the upper surface of the light-transmitting material layer 23, or by deposition and patterning (for example, first using physical vapor deposition to form a light-shielding material layer, and then using a photolithography process to perform patterning to obtain the corresponding light-shielding layer 22 with a plurality of light-transmitting holes 221). Of course, it is not limited to this. The light-shielding layer 22 can also be a light-shielding ink layer or a light-shielding metal layer, or a light-shielding layer of other materials.

[0059] Among them, the light-transmitting material layer 23 is formed of a light-transmitting material with good light-transmitting performance. The light-transmitting material layer 23 is used to construct an appropriate imaging distance between the photosensitive sensor array 202 and the optical imaging layer 21. The thickness of the light-transmitting material layer 23 can be adjusted based on the need for the imaging distance.

[0060] Among them, the photosensitive sensor array 202 includes a silicon-based substrate and a plurality of photosensitive elements disposed on the silicon-based substrate. The plurality of photosensitive elements are distributed in a rectangular array. The plurality of photosensitive elements form a photosensitive surface of the photosensitive sensor array 202. The second photosensitive area 202b of the photosensitive surface is disposed around the first photosensitive area 202a of the photosensitive surface. Alternatively, the second photosensitive area 202b can be disposed on one side or multiple sides of the first photosensitive area 202a. For example, the second photosensitive area 202b can also be disposed side by side with or intersect the first photosensitive area 202a. In this embodiment, the second photosensitive area 202b is disposed around the first photosensitive area 202a (as Figure 4 shown).

[0061] Specifically, the first photosensitive area 202a can be rectangular, for example, it can be square or rectangular. Of course, it can also be of other shapes.

[0062] The first photosensitive area 202a includes a plurality of first photosensitive sub-areas 2021a. Each first photosensitive sub-area 2021a corresponds to one or more second optical elements respectively, and the corresponding first photosensitive sub-area 2021a and the second optical element are disposed opposite to each other. The second optical element is used to image the fingerprint to be measured in its corresponding first photosensitive sub-area 2021a. The first photosensitive sub-area 2021a generates a corresponding first signal according to the reflected light of the fingerprint.

[0063] Among them, the first photosensitive sub-region 2021a is provided with a plurality of first photosensitive pixels 20211a, and the plurality of first photosensitive pixels 20211a are closely arranged in a matrix. Each first photosensitive pixel 20211a is rectangular or square in shape. Of course, it is not limited thereto.

[0064] Among them, the second photosensitive region 202b is in the shape of a hollow rectangle, such as a square or a rectangle. Of course, it can also be other shapes. The second photosensitive region 202b is provided with a plurality of second photosensitive sub-regions 2021b. The plurality of second photosensitive sub-regions 2021b correspond to the plurality of first optical elements. Among them, each first optical element is used to image a fingerprint in the corresponding second photosensitive sub-region according to the reflected light of the fingerprint, and the second photosensitive sub-region 2021b is used to generate a second signal according to the reflected light of the fingerprint. The number of the plurality of second photosensitive sub-regions 2021b can be two or more than two. The at least two second photosensitive sub-regions 2021b can measure the depth information of the valleys and ridges based on the binocular ranging principle or the n-eye ranging principle.

[0065] Among them, each second photosensitive sub-region 2021b includes a plurality of second photosensitive pixels 20211b, and the plurality of second photosensitive pixels 20211b can be closely distributed in a rectangular array in each second photosensitive sub-region 2021b. The second photosensitive pixel 20211b can be rectangular in shape, such as a rectangle or a square. Of course, it can also be other shapes. As Figure 5 shown, both CD and EF contain a pair of valley-ridge information. According to the requirements of the Nyquist sampling frequency, at least four second photosensitive pixels should be used to collect this pair of valley-ridges. Therefore, the size of the second photosensitive pixels needs to be set relatively small. For example, the area of each first photosensitive pixel 20211a in at least part of the first photosensitive pixels 20211a is larger than the area of each of the second photosensitive pixels 20211b. Or, the area of each of the second photosensitive pixels in at least part of the second photosensitive pixels is smaller than the area of each of the first photosensitive pixels. Of course, as a preferred implementation, the area of each first photosensitive pixel is larger than the area of each of the second photosensitive pixels. For example, the area of each first photosensitive pixel is set to x, and the area of each second photosensitive pixel is set to y, where x is greater than y.

[0066] For example, the side length of the first photosensitive pixel 20211a can be twice the side length of the second photosensitive pixel 20211b, so that the number of first photosensitive pixels with the same area can be reduced, thereby achieving the purpose of reducing costs.

[0067] When binocular ranging is adopted, the multiple second photosensitive sub-regions 2021b include at least a pair of corresponding second photosensitive sub-regions 2021b. A fingerprint image can be generated based on the second photosensitive signals generated by the at least a pair of corresponding second photosensitive sub-regions 2021b, and then position signals of a first ridge image and a second ridge image can be determined in the fingerprint image, so that the interval distance between the first ridge image and the second ridge image can be calculated, and further the depth information of the fingerprint ridges can be calculated. Similarly, position signals of a first valley image and a second valley image can be calculated based on the fingerprint image, so that the interval distance between the first valley image and the second valley image can be calculated, and further the depth information of the fingerprint valleys can be calculated.

[0068] Of course, it can be understood that the at least a pair of corresponding second photosensitive sub-regions 2021b may include one or more pairs of corresponding second photosensitive sub-regions, so that multiple groups of corresponding second photosensitive sub-regions can be used to calculate the depth information of multiple valleys and the depth information of multiple ridges, and then the average value can be taken to improve the accuracy of live body recognition and avoid misjudgment.

[0069] Specifically, when binocular ranging is adopted, the detection principle of the depth information is as Figure 5As shown in the figure, points A and B respectively represent a set of adjacent valleys and ridges of the fingerprint, and the height difference between the valley and the ridge is represented by d. MN constitutes the equivalent image plane of the optical imaging layer 21, and the actual image plane M1N1 is on the photosensitive surface of the photosensitive sensor array 202. Among them, point C1 corresponds to the first ridge image, point D1 corresponds to the first valley image, point E1 corresponds to the second ridge image, F1 corresponds to the second valley image, point C corresponds to the equivalent image of the first ridge image, point D corresponds to the equivalent image of the first valley image, point E corresponds to the equivalent image of the second ridge image, and F corresponds to the equivalent image of the second valley image. Among them, triangle C1E1A is similar to triangle O1O2A. Therefore, according to the triangle similarity theorem, it can be obtained that: C1E1 / O1O2 = GM1 / GO1; where, C1E1 is the interval distance between the first ridge image and the second ridge image. Since the position signals of the first ridge image and the second ridge image can be obtained from the image of the fingerprint generated by the induction, the interval distance C1E1 between the first ridge image and the second ridge image can be calculated accordingly. O1O2 is the interval distance between the two first optical elements corresponding to the two second photosensitive sub-regions 2021b, and it is a constant value. GM1 is the distance value between the ridge of the fingerprint and the photosensitive sensor array 202. GO1 is the distance value between the ridge of the fingerprint and the corresponding second optical element. Since GM1 = O1M1 + GO1, O1M1 is the distance value between the second optical element and the photosensitive sensor array 202, and it is a constant, generally the focal length of the second optical element. GM1 = O1M1 + GO1 can be substituted into the relational expression C1E1 / O1O2 = GM1 / GO1 to calculate the value of GM1, that is, the depth information of the ridge of the fingerprint relative to the photosensitive sensor array 202. Of course, it can be understood that in some embodiments, if the ridge of the fingerprint is in direct contact with the upper surface of the display device, the distance value between the upper surface of the display device and the photosensitive sensor array 202 can also be used as the depth information of the ridge of the fingerprint.

[0070] Similarly, since triangle D1F1B is similar to triangle O1O2B, therefore, according to the triangle similarity theorem, the relational expression can be obtained: KM1 / KO1 = D1F1 / O1O2.

[0071] Among them, since KM1 = KO1 + O1M1, substituting KM1 = KO1 + O1M1 into the relational expression KM1 / KO1 = D1F1 / O1O2 can calculate the value of KM1, that is, the depth information of the valley of the fingerprint relative to the photosensitive sensor array 202.

[0072] Among them, according to the requirements of the Nyquist sampling frequency, there should be at least four second photosensitive pixels 20211b to capture the images of this pair of adjacent valleys and ridges, so as to form a pair of valley images and ridge images. For example, the second photosensitive sub-region 2021b is rectangular, and the second photosensitive sub-region 2021b is provided with a plurality of second photosensitive pixels distributed in a matrix, and the number of rows and columns of the second photosensitive pixels in each second photosensitive sub-region is greater than or equal to 4. Of course, if the second photosensitive sub-region is square, the number of rows and columns of the second photosensitive pixels 20211b in each second photosensitive sub-region 2021b is equal to 4.

[0073] Please continue to refer to Figure 5 , according to the geometric relationship, the relational expressions can be obtained: GA / MC = GO1 / MO1, KB / MD = KO1 / MO1.

[0074] According to the above relational expressions, it can be obtained that: CD = MD - MC = KB*MO1 / KO1 - GA*MO1 / GO1. Among them, KB and GA are the corresponding relationships between the optical elements and the fingerprint, which can be defined in advance as constants, MO1 is the focal length f of the optical element, GO1 is the distance from the upper surface of the display device 10 to the optical element (approximately equal to the distance from the ridge of the fingerprint to the optical element), and KO1 is the distance from the valley of the fingerprint to the optical element. After calculating the lengths of CD and EF, when designing the photosensitive sensor array, it should be ensured that the widths of CD and EF are greater than or equal to 4 times the side length of the second photosensitive pixel 20211b, so as to ensure that the resolution of the second photosensitive sub-region 2021b meets the requirements of live body recognition. That is to say, when the second photosensitive pixel 20211b is square, the short side length of the second photosensitive pixel 20211b is less than or equal to β*p / 4, where β is the magnification of the optical structure layer and p is the empirical pitch value of a pair of adjacent valleys and ridges of the fingerprint. The empirical pitch value is obtained based on the valley and ridge pitches of fingerprints of various age groups and ethnic groups statistically analyzed from big data. When the second photosensitive pixel 20211b is square, the side length of the second photosensitive pixel 20211b is less than or equal to β*p / 4. Of course, the smaller the size of the second photosensitive pixel 20211b, the higher the accuracy of live body judgment.

[0075] Please continue to refer to Figures 1-3As shown in the figure, an embodiment of the present application further provides an electronic device. The electronic device includes a display device 10 and a fingerprint recognition module 20 disposed below the display device 10. Among them, the display device 10 may be an OLED (Organic Light-Emitting Diode, for short) display device. Of course, it may also be other display devices, such as a QLED display device. When the display device 10 is an OLED display device, it is usually composed of a transparent substrate and a light-emitting functional layer disposed on the transparent substrate. The light-emitting functional layer includes a cover glass, a polarizer and a touch panel (POL&Touch), an encapsulation layer, and a corresponding control circuit (not shown in the figure). Among them, the transparent substrate may be a glass substrate or a transparent substrate made of a flexible material, such as a PI substrate. Of course, the display device 10 may also be a liquid crystal display device. Correspondingly, the area of the display device 10 opposite to the fingerprint recognition module 20 is set as a light-transmitting area, so that the reflected light of the finger can reach the fingerprint recognition module 20 through the light-transmitting area for corresponding fingerprint recognition and liveness recognition.

[0076] Please refer to Figure 6 , Figure 6 is a flowchart of a fingerprint recognition method in some embodiments of the present application, which is applied to an electronic device, and the electronic device may be the electronic device in any of the above embodiments. Among them, the fingerprint recognition method includes the following steps:

[0077] S101. Obtain a second signal generated by the fingerprint recognition module sensing the image of the fingerprint to be measured.

[0078] S102. Generate depth information of the fingerprint according to the second signal.

[0079] S103. Perform fingerprint liveness recognition according to the depth information.

[0080] Among them, in step S101, the second signal is generated by a photosensitive sensor array sensing the image formed by the fingerprint to be measured in the second photosensitive area of the photosensitive sensor array. Among them, the image of the fingerprint includes the valley image and the ridge image of the fingerprint. Step S101 is specifically: respectively obtain the second position signals generated by adjacent two second photosensitive sub-areas sensing the valley image of the fingerprint; respectively obtain the second position signals generated by adjacent two second photosensitive sub-areas sensing the ridge image of the fingerprint.

[0081] Among them, in step S102, the depth information includes the depth information of the valleys of the fingerprint and / or the depth information of the ridges of the fingerprint. Step S102 includes:

[0082] S1021. Generate an image of the fingerprint based on the second signal; S1022. Obtain a first position signal of the ridges of the fingerprint imaged in the image through a first optical element and a second position signal of the ridges of the fingerprint imaged in the image through a second optical element; S1023. Obtain a third position signal of the valleys of the fingerprint imaged in the image through a third optical element and a fourth position signal of the ridges of the fingerprint imaged in the image through a fourth optical element; S1024. Generate depth information of the ridges of the fingerprint based on the first position signal and the second position signal; S1025. Generate depth information of the valleys of the fingerprint based on the third position signal and the fourth position signal. Wherein, the image of the fingerprint includes the photosensitive signal intensity of each pixel point and the position signal of the pixel point. Among them, the interval distance of the ridges of the fingerprint imaged at two different positions can be calculated according to the first position signal and the second position signal, and the interval distance of the valleys of the fingerprint imaged at two different positions can be calculated according to the third position signal and the fourth position signal. The method for calculating depth information based on the interval distance has been described in detail in the above embodiments, and thus will not be elaborated here.

[0083] It can be understood that in some embodiments, the corresponding depth information can be calculated by calculating the position signals of the valley image and the ridge image in the images formed by two adjacent optical elements. That is, the first optical element is adjacent to the second optical element, the third optical element is the same optical element as the first optical element, and the fourth optical element is the same optical element as the second optical element.

[0084] Among them, in step S103, fingerprint liveness recognition can be performed based on the depth information of the valleys of the fingerprint. For example, a distance threshold can be set. The distance between the valleys of the fingerprint of a real finger and the photosensitive sensor array should be greater than the distance between the valleys of the fingerprint in the 2D picture and the photosensitive sensor array. Since the 2D picture is flat, the distance between the valleys of the fingerprint in the 2D picture and the upper surface of the display device is almost 0. The distance threshold can be set as the distance between the upper surface of the display device and the photosensitive sensor array. When the detected distance corresponding to the depth information is greater than the distance threshold, it is determined that the fingerprint liveness recognition passes; when it is less than or equal to the distance threshold, the fingerprint liveness recognition fails.

[0085] Fingerprint liveness recognition can also be performed based on the depth information of the ridges of the fingerprint. For example, a distance threshold can be set. Since the finger is elastic and makes more sufficient contact with the surface of the display device, the gap between the real finger and the upper surface of the display device should be smaller than the gap between the ridges of the fingerprint in the 2D image and the upper surface of the display device. Therefore, the distance between the ridges of the fingerprint of the real finger and the photosensitive sensor array should be smaller than the distance between the ridges of the fingerprint in the 2D image and the photosensitive sensor array. When the detected distance corresponding to the depth information is greater than the distance threshold, it is determined that the fingerprint liveness recognition fails; when it is less than or equal to the distance threshold, the fingerprint liveness recognition passes.

[0086] Of course, fingerprint liveness detection can also be implemented based on the depth information of the valleys and ridges of the fingerprint. Specifically, step S103 includes: S1031, calculating the height difference information between the valleys and ridges of the fingerprint according to the depth information of the valleys and the depth information of the ridges of the fingerprint; S1032, performing fingerprint liveness recognition according to the height difference information. Among them, when the height difference between the valleys and ridges is greater than the preset threshold, it is determined that the fingerprint liveness recognition passes; when the height difference between the valleys and ridges is less than or equal to the preset threshold, it is determined that the fingerprint liveness recognition fails.

[0087] Please refer to Figure 7 , Figure 7 is a schematic structural diagram of a fingerprint recognition device in some embodiments of the present application. The fingerprint recognition device includes: an acquisition module 301, configured to acquire a second signal generated by the fingerprint recognition module sensing an image of a fingerprint to be measured; a generation module 302, configured to generate depth information of the fingerprint according to the second signal; and an identification module 303, configured to perform fingerprint liveness recognition according to the depth information.

[0088] The above are only embodiments of the present application and are not used to limit the protection scope of the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A fingerprint recognition module, which is used to be arranged under a display device, and is characterized in that, Comprising: An optical structure layer for transmitting the reflected light of the fingerprint on the display device, the optical structure layer including a plurality of first optical elements; A photosensitive sensor array including a first photosensitive area and a second photosensitive area; the first photosensitive area is used to generate a first signal for fingerprint recognition according to the reflected light, and the second photosensitive area is used to generate a second signal for calculating the depth information of the fingerprint according to the reflected light, the depth information is used for liveness recognition, and the depth information includes the depth information of the valleys of the fingerprint and / or the depth information of the ridges of the fingerprint; The fingerprint recognition module is configured to: Generate an image of the fingerprint according to the second signal; Obtain a first position signal of the ridge of the fingerprint imaged in the image through the first optical element and a second position signal of the ridge of the fingerprint imaged in the image through the second optical element; Obtain a third position signal of the valley of the fingerprint imaged in the image through the third optical element and a fourth position signal of the valley of the fingerprint imaged in the image through the fourth optical element; Generate the depth information of the ridge of the fingerprint according to the first position signal and the second position signal; Generate the depth information of the valley of the fingerprint according to the third position signal and the fourth position signal.

2. The fingerprint recognition module according to claim 1, and is characterized in that, The first photosensitive area is provided with a plurality of first photosensitive pixels, and the second photosensitive area is provided with a plurality of second photosensitive pixels, The area of each first photosensitive pixel in at least part of the first photosensitive pixels is larger than the area of each second photosensitive pixel; or, the area of each second photosensitive pixel in at least part of the second photosensitive pixels is smaller than the area of each first photosensitive pixel.

3. The fingerprint recognition module according to claim 2, and is characterized in that, The area of each first photosensitive pixel is larger than the area of each second photosensitive pixel.

4. The fingerprint recognition module according to claim 1, and is characterized in that, The second photosensitive area is provided with a plurality of second photosensitive pixels, the second photosensitive pixels are rectangular, and the length of the short side of the second photosensitive pixel is less than or equal to β*p / 4, where β is the magnification of the optical structure layer and p is the empirical pitch value of a pair of adjacent valleys and ridges of the fingerprint.

5. The fingerprint recognition module according to claim 4, and is characterized in that, The second photosensitive pixel is square.

6. The fingerprint recognition module according to any one of claims 1-5, and is characterized in that, The second photosensitive area includes a plurality of second photosensitive sub-areas, the optical structure layer includes a plurality of first optical elements, and the plurality of first optical elements respectively correspond to the plurality of second photosensitive sub-areas, and each first optical element is used to transmit the reflected light to the corresponding second photosensitive sub-area.

7. The fingerprint recognition module according to claim 6, and is characterized in that, The second photosensitive sub-area is rectangular; the second photosensitive sub-area is provided with a plurality of second photosensitive pixels distributed in a matrix, and the number of rows and columns of the second photosensitive pixels in each second photosensitive sub-area is greater than or equal to 4.

8. The fingerprint recognition module according to any one of claims 1-5, and is characterized in that, The second photosensitive area is disposed around the first photosensitive area, or the second photosensitive area is disposed on one side or multiple sides of the first photosensitive area.

9. The fingerprint recognition module according to claim 8, and is characterized in that, The first photosensitive area is rectangular, and the second photosensitive area is in a hollow rectangular shape and disposed around the first photosensitive area.

10. An electronic device, and is characterized in that, Comprising the fingerprint recognition module according to any one of claims 1-9 and a display device, and the fingerprint recognition module is disposed below the display device.

11. A fingerprint recognition method, and is characterized in that, Applied to an electronic device, the electronic device includes a fingerprint recognition module, and the method includes: Obtain a second signal generated by the fingerprint recognition module based on the reflected light of the fingerprint; Generate depth information of the fingerprint according to the second signal; the depth information includes depth information of fingerprint valleys and / or depth information of fingerprint ridges; Perform fingerprint liveness recognition according to the depth information; The generating the depth information of the fingerprint according to the second signal includes: Generate an image of the fingerprint according to the second signal; Obtain a first position signal of the fingerprint ridge imaged in the image through a first optical element and a second position signal of the fingerprint ridge imaged in the image through a second optical element; Obtain a third position signal of the fingerprint valley imaged in the image through a third optical element and a fourth position signal of the fingerprint valley imaged in the image through a fourth optical element; Generate depth information of the fingerprint ridge according to the first position signal and the second position signal; Generate depth information of the fingerprint valley according to the third position signal and the fourth position signal.

12. The fingerprint recognition method according to claim 11, wherein, The performing fingerprint liveness recognition according to the depth information includes: Calculate height difference information between the fingerprint valleys and ridges according to the depth information of the fingerprint valleys and the depth information of the fingerprint ridges; Perform fingerprint liveness recognition according to the height difference information.

13. A fingerprint recognition device, wherein, It includes: An acquisition module, configured to obtain a second signal generated by the fingerprint recognition module according to the reflected light of the fingerprint to be measured; A generation module, configured to generate depth information of the fingerprint according to the second signal; the depth information includes depth information of fingerprint valleys and / or depth information of fingerprint ridges; An identification module, configured to perform fingerprint liveness recognition according to the depth information; The generation module is specifically configured to: Generate an image of the fingerprint according to the second signal; Obtain a first position signal of the fingerprint ridge imaged in the image through a first optical element and a second position signal of the fingerprint ridge imaged in the image through a second optical element; Obtain a third position signal of the fingerprint valley imaged in the image through a third optical element and a fourth position signal of the fingerprint valley imaged in the image through a fourth optical element; Generate depth information of the fingerprint ridge according to the first position signal and the second position signal; Generate depth information of the fingerprint valley according to the third position signal and the fourth position signal.

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