Fingerprint recognition substrate, fingerprint recognition method and display device

Abstract

The present application provides a fingerprint recognition substrate and a fingerprint recognition method and a display device, wherein the fingerprint recognition substrate includes: a substrate substrate; a plurality of point light sources arranged on one side of the substrate substrate, each point light source is used to emit signal light; an optical layer and a photosensitive layer stacked on the side of the substrate substrate away from the point light source, the optical layer is arranged close to the substrate substrate, the photosensitive layer includes a plurality of photosensitive units, the optical layer is used to make the signal light of each point light source reflected by the finger incident on different photosensitive units, and each photosensitive unit is used to receive the signal light emitted by the optical layer for fingerprint recognition. The technical solution of the present application arranges an optical layer between the point light source and the photosensitive layer, so that the signal light of each point light source reflected by the finger is incident on different photosensitive units, thereby ensuring that multiple point light sources with a close distance are illuminated at a single time without mixing the light, so that a fingerprint image with a larger area and more continuous can be obtained by a single imaging, thereby improving the efficiency of fingerprint recognition.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to a fingerprint recognition substrate, a fingerprint recognition method, and a display device. Background Art

[0002] Thanks to the breaking of the OLED (Organic Light Emitting Diode) production capacity bottleneck and the gradual improvement of OLED screen production technology maturity, production costs have gradually decreased. The current new optical fingerprint recognition technology has abandoned the traditional optical fingerprint light path structure and instead borrowed the light from the display screen as the light source. The current mainstream solution is to perform optical fingerprint recognition through a self-luminous OLED screen. Since the latest fingerprint imaging solution abandons the traditional light path structure, the thickness of the entire imaging system is reduced, and the cost of the imaging system is also reduced. This new optical fingerprint recognition technology without an optical path structure includes point light source imaging, line light source imaging and other solutions. Among them, point light source imaging uses the large-angle light emitted by the OLED to be fully reflected at the fingerprint valley position on the interface formed by the OLED and the finger, while the reflectivity at the fingerprint ridge position is lower. These reflected light rays are collected by the photosensitive sensing unit to generate a fingerprint pattern.

[0003] Because the fundamental principle of point light source imaging is to utilize total optical reflection, a fingerprint image is formed outside the full reflection angle. Within the full reflection angle, a darker circular area forms, and the fingerprint within this area cannot be effectively identified. Related technologies require multiple scans and imaging of the finger, and then stitching these multiple fingerprint images together to produce a continuous, complete fingerprint image. However, multiple imaging takes a long time, resulting in low fingerprint recognition efficiency and making it unsuitable for scenarios requiring high real-time performance. Summary of the Invention

[0004] The present invention provides a fingerprint recognition substrate, a fingerprint recognition method, and a display device to improve the efficiency of fingerprint recognition.

[0005] In order to solve the above problems, the present invention discloses a fingerprint recognition substrate, which includes:

[0006] substrate;

[0007] A plurality of point light sources are provided on one side of the substrate, each of the point light sources is used to emit signal light;

[0008] An optical layer and a photosensitive layer are stacked on the side of the base substrate away from the point light source, the optical layer is arranged close to the base substrate, and the photosensitive layer includes a plurality of photosensitive units. The optical layer is used to input the signal light of each point light source reflected by the finger into different photosensitive units, and each photosensitive unit is used to receive the signal light emitted by the optical layer for fingerprint recognition.

[0009] In an optional implementation, the optical layer includes a first light-shielding layer, the first light-shielding layer includes a plurality of first light-shielding units, each of the first light-shielding units includes a first light-shielding area and a first opening area, the orthographic projection of the first light-shielding area on the photosensitive layer covers a first preset number of photosensitive units, and the orthographic projection of the first opening area on the photosensitive layer covers a second preset number of photosensitive units.

[0010] In an optional implementation, the shape of the first opening area is a square, and the size of the first light-shielding layer satisfies the following formula: (a+b / 2)>2.7h1, wherein a is the side length of the first opening area, b is the interval width between two adjacent first opening areas, and h1 is the distance between the first light-shielding layer and the photosensitive layer.

[0011] In an optional implementation, the optical layer also includes a second light-shielding layer arranged on the side of the first light-shielding layer away from the base substrate, the second light-shielding layer includes a plurality of second light-shielding units, each of the second light-shielding units includes a second light-shielding area and a second opening area, the orthographic projection of the second light-shielding area on the photosensitive layer covers the second preset number of photosensitive units, and the orthographic projection of the second opening area on the photosensitive layer covers the first preset number of photosensitive units.

[0012] In an optional implementation, the shape of the first opening area is a square, and the sizes of the first light-shielding layer and the second light-shielding layer satisfy the following formula: (a+b / 2)>2.7(h1+h2), wherein a is the side length of the first opening area, b is the interval width between two adjacent first opening areas, h1 is the distance between the first light-shielding layer and the second light-shielding layer, and h2 is the distance between the second light-shielding layer and the photosensitive layer.

[0013] In an optional implementation, the orthographic projection of the second light-shielding area on the photosensitive layer covers the orthographic projection of the first opening area on the photosensitive layer, the shape of the second light-shielding area is a square, and the sizes of the first light-shielding layer and the second light-shielding layer satisfy the following formula: (ca)<0.9h1, and c<2.7h1, where c is the side length of the second light-shielding area.

[0014] In an optional implementation, the orthographic projection of the second light-shielding area on the photosensitive layer completely overlaps with the orthographic projection of the first opening area on the photosensitive layer and the photosensitive unit, the shape of the second light-shielding area is a square, and the sizes of the first light-shielding layer and the second light-shielding layer satisfy the following formula: b=2a, 0.37a≤h1<0.74a, 0≤h2

[0015] In an optional implementation, the optical layer includes a plurality of microlens units, and the orthographic projection of each microlens unit on the photosensitive layer covers a third preset number of photosensitive units, where the third preset number is greater than 1.

[0016] In order to solve the above problem, the present invention further discloses a fingerprint recognition device, which includes the fingerprint recognition substrate described in any embodiment.

[0017] In order to solve the above problems, the present invention further discloses a fingerprint recognition method, which is applied to the fingerprint recognition substrate described in any embodiment, and the method comprises:

[0018] When a finger is detected touching the fingerprint recognition substrate, the plurality of point light sources in the touch area are illuminated;

[0019] generating an initial fingerprint image according to the fingerprint electrical signal of the photosensitive unit, wherein the fingerprint electrical signal is generated by the photosensitive unit according to the received signal light;

[0020] extracting the fingerprint image of each point light source from the initial fingerprint image according to the corresponding relationship between each point light source and the photosensitive unit;

[0021] Performing homogenization processing on the fingerprint image of each point light source;

[0022] The fingerprint images of the point light sources after the homogenization process are spliced ​​to obtain a target fingerprint image.

[0023] In an optional implementation, the fingerprint image of each point light source includes a non-imaging area, and the step of lighting up the plurality of point light sources within the touch area includes:

[0024] The plurality of point light sources within the touch area are illuminated according to a preset arrangement rule, wherein the preset arrangement rule is that the non-imaging area of ​​each point light source is circumscribed.

[0025] In an optional implementation, the step of performing homogenization processing on the fingerprint image of each point light source includes:

[0026] ​Performing brightness correction on the fingerprint image of each of the point light sources using a pre-calibrated standard brightness distribution;

[0027] summing the brightness of each photosensitive unit in a photosensitive area in the fingerprint image of each point light source after brightness correction, and using the summed result as the brightness of the photosensitive area, wherein the photosensitive area includes the photosensitive units covered by the orthographic projection of the first light shielding unit on the photosensitive layer;

[0028] The step of stitching the fingerprint images of the point light sources after the homogenization process is completed comprises:

[0029] When the fingerprint images of the point light sources have an overlapping area, the brightness of the fingerprint images of the point light sources in the same photosensitive area in the overlapping area is averaged or weighted summed to obtain the brightness of the target fingerprint image in the same photosensitive area.

[0030] In an optional implementation, before the step of performing brightness correction on the fingerprint image of each of the point light sources using the pre-calibrated standard brightness distribution, the method further includes:

[0031] In a dark room, light up point light sources at different positions in turn;

[0032] Obtaining an original image of each of the point light sources according to a calibration electrical signal of the photosensitive unit, wherein the calibration electrical signal is generated by the photosensitive unit according to the received signal light;

[0033] The brightness of the sensing units at the same relative position in the original images of all the point light sources is averaged to obtain the standard brightness distribution, where the relative position is the position of the sensing unit relative to the corresponding point light source.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] The technical solution of the present application provides a fingerprint recognition substrate, a fingerprint recognition method, and a display device, wherein the fingerprint recognition substrate includes: a base substrate; a plurality of point light sources arranged on one side of the base substrate, each point light source being used to emit signal light; an optical layer and a photosensitive layer stacked on the side of the base substrate away from the point light sources, the optical layer being arranged close to the base substrate, the photosensitive layer including a plurality of photosensitive units, the optical layer being used to direct the signal light from each point light source reflected by the finger into a different photosensitive unit, each photosensitive unit being used to receive the signal light emitted by the optical layer for fingerprint recognition. The technical solution of the present application provides an optical layer between the point light source and the photosensitive layer, so that the signal light from each point light source reflected by the finger is incident on a different photosensitive unit, thereby ensuring that multiple point light sources at a close distance are illuminated at a single time without mixing the light, so that a larger and more continuous fingerprint image can be obtained by a single imaging, thereby improving the efficiency of fingerprint recognition. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0037] Figure 1 A schematic diagram showing the principle of point light source imaging in optical fingerprint recognition technology without an optical path structure;

[0038] Figure 2 The image of the fingerprint formed by a point light source is shown;

[0039] Figure 3 A schematic diagram of single-shot imaging of a single point light source is shown;

[0040] Figure 4 The fingerprint image obtained by stitching two images is shown;

[0041] Figure 5 A schematic diagram of a fingerprint image obtained by stitching 12 images is shown;

[0042] Figure 6 A schematic diagram of a fingerprint image obtained by stitching two images is shown;

[0043] Figure 7 A schematic cross-sectional structure diagram of a fingerprint recognition substrate provided by an embodiment of the present application is shown;

[0044] Figure 8 A schematic cross-sectional structure diagram of an optical layer provided in one embodiment of the present application is shown;

[0045] Figure 9 A schematic cross-sectional structure diagram of another optical layer provided in one embodiment of the present application is shown;

[0046] Figure 10 A schematic diagram of the planar structure of a first light-shielding layer provided in one embodiment of the present application is shown;

[0047] Figure 11 A schematic diagram of the planar structure of the second light-shielding layer provided in one embodiment of the present application is shown;

[0048] Figure 12 A schematic cross-sectional structure diagram of another fingerprint recognition substrate provided in one embodiment of the present application is shown;

[0049] Figure 13 A schematic diagram showing the relationship between original objects in the related art is shown;

[0050] Figure 14 A schematic diagram showing the relationship between objects and images of a fingerprint recognition substrate provided in one embodiment of the present application is shown;

[0051] Figure 15 A simulated imaging diagram of four point light sources simultaneously lit up according to an embodiment of the present application is shown;

[0052] Figure 16 A schematic diagram of imaging of simulating finger pressing provided by an embodiment of the present application is shown;

[0053] Figure 17 A flowchart of a fingerprint recognition method according to an embodiment of the present invention is shown;

[0054] Figure 18 A schematic flow chart of a fingerprint recognition method provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0055] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0056] Reference Figure 1 The basic principle of point light source imaging is to use the total reflection of the incident light on the finger touch surface. The light with an incident angle greater than the total reflection angle is totally reflected in the fingerprint valley area due to the presence of air, forming a brighter signal on the photosensitive layer sensor; on the contrary, in the fingerprint ridge area, since the total reflection is destroyed, less light is reflected from the fingerprint ridge area to the photosensitive layer sensor, thus forming a darker signal on the photosensitive layer sensor. Therefore, a fingerprint image with alternating light and dark can be formed in the area outside the full reflection angle, such as Figure 2 As shown. Within the total reflection angle (light with an incident angle less than the total reflection angle), less light is reflected to the photosensitive layer sensor, so a darker circular area will be seen in the fingerprint image, as shown Figure 3 As shown, the black part is the non-imaging area, and the white circle is the fingerprint imaging area.

[0057] Since point light source imaging is magnified imaging, the image formed on the photosensitive layer sensor after the signal light of the point light source is reflected by the finger is an upright magnified image. Therefore, in order to avoid mutual interference between light sources, two light sources with a close distance cannot be lit at the same time. That is, the point light sources that are lit at the same time are in a discrete state on the object side. Figure 5 Schematic diagram of the distribution of object-side point light sources (4-point objects).

[0058] In practical applications, in order to obtain a complete fingerprint image, point light sources at different locations are generally illuminated multiple times. The non-imaging area of ​​each point light source is just covered by the imaging area of ​​other point light sources, so that a complete fingerprint image can be obtained. In this way, by illuminating point light sources at different locations during multiple imaging processes, the mutual influence between light sources is avoided from the time dimension. Figure 4 The fingerprint image obtained by stitching two images is shown. Figure 5 A schematic diagram of a fingerprint image obtained by stitching 12 images is also shown.

[0059] If only one point light source is lit at a time, refer to Figure 6 The schematic diagram of the fingerprint image obtained by stitching two single-point light source images is shown. A seamless fingerprint pattern can be obtained, but the imaging area is slightly smaller. In practical applications, if you want to obtain a fingerprint image of a larger area, multiple imaging is still required.

[0060] However, multiple imaging takes a long time and the fingerprint recognition efficiency is low, which cannot be used in scenarios with high real-time requirements.

[0061] In order to improve the efficiency of fingerprint recognition, an embodiment of the present application provides a fingerprint recognition substrate. Figure 7 , the fingerprint recognition substrate may include:

[0062] Base substrate 71;

[0063] and a plurality of point light sources 72 disposed on one side of the base substrate 71, each point light source 72 being configured to emit a signal light;

[0064] An optical layer 73 and a photosensitive layer 74 are stacked on the side of the base substrate 71 away from the point light source 72. The optical layer 73 is arranged close to the base substrate 71. The photosensitive layer 74 includes a plurality of photosensitive units 741. The optical layer 73 is used to input the signal light of each point light source 72 reflected by the finger into different photosensitive units 741. Each photosensitive unit 741 is used to receive the signal light emitted by the optical layer 73 for fingerprint recognition.

[0065] The fingerprint recognition substrate provided in this embodiment may be an OLED display substrate, and each point light source 72 may include a plurality of OLED pixel units.

[0066] The optical layer 73 may be a grating (eg Figure 8 or Figure 9 as shown) or microlens array (as Figure 12 The structure of the optical layer can only pass signal light within a specific angle range. The specific structure of the optical layer will be described in detail in the subsequent embodiments.

[0067] Reference Figure 7By setting an optical layer 73 between the substrate 71 and the photosensitive layer 74, it is possible to ensure that the signal light from each point light source 72 is incident on different photosensitive units 741, thereby avoiding interference between the point light sources 72 that are lit at the same time and are close to each other during imaging, and achieving that the light from different point light sources 72 is not mixed on the photosensitive layer 74. In this way, by lighting multiple point light sources 72 that are close to each other at a single time, a larger and denser fingerprint image can be obtained, such as Figure 14 shown.

[0068] The fingerprint recognition substrate provided in this embodiment provides an optical layer between the point light source and the photosensitive layer, so that the signal light from each point light source reflected by the finger is incident on different photosensitive units, thereby ensuring that multiple point light sources at relatively close distances are illuminated at a single time without light mixing, so that a larger area and more dense fingerprint image can be obtained in a single imaging, thereby improving fingerprint recognition efficiency.

[0069] In an optional implementation, the optical layer 73 includes a first light shielding layer 81. Figure 8 The cross-sectional structure diagram of the first light shielding layer 81 is shown. Figure 10 Schematic diagram of the planar structure of the first light-shielding layer 81 is shown. The first light-shielding layer 81 includes a plurality of first light-shielding units 101 . Each first light-shielding unit 101 includes a first light-shielding area 1011 and a first opening area 1012 .

[0070] In order to ensure that the range of images formed by light emitted from point light sources at different locations, after passing through the first light-shielding layer 81 and incident on the photosensitive layer 74, is consistent, the relative positions of the first light-shielding units 101 and the photosensitive units 741 can be fixed. For example, the orthographic projection of the first light-shielding area 1011 on the photosensitive layer 74 covers a first preset number of photosensitive units 741, and the orthographic projection of the first opening area 1012 on the photosensitive layer 74 covers a second preset number of photosensitive units 741.

[0071] Figure 10 The first preset number shown in FIG is 8, and the second preset number is 1. Figure 10 The orthographic projection of each first light-shielding unit 101 on the photosensitive layer 74 covers 3*3 photosensitive units 741 (as shown by the dotted line); the orthographic projection of the first light-shielding area 1011 on the photosensitive layer 74 covers 8 photosensitive units 741; the orthographic projection of the first opening area 1012 on the photosensitive layer 74 covers 1 photosensitive unit 741, and the first opening area 1012 is located at the center of the first light-shielding unit 101. The shape of the first opening area 1012 can be the same as that of the photosensitive unit 741, for example, it can be a square.

[0072] Since the incident angle range of the light that can effectively form an image from a point light source is 42° to 70°, in order to ensure that as much effective imaging light as possible is incident on the photosensitive layer 74, and at the same time ensure that the light emitted by the point light sources 72 at multiple positions is incident on different photosensitive units 741, refer to Figure 8 The size of the first light-shielding layer 81 can satisfy the following formula: (a+b / 2)>2.7h1, where a is the side length of the first opening area 1012, b is the interval width between two adjacent first opening areas 1012, and h1 is the distance between the first light-shielding layer 81 and the photosensitive layer 74. This can prevent light from different point light sources from mixing.

[0073] By setting a first light-shielding layer 81 between the base substrate 71 and the photosensitive layer 74, and reasonably setting the sizes of the first light-shielding area 1011 and the first opening area 1012, it can be ensured that only light with an incident angle within a specific range passes through the first light-shielding layer 81 into the photosensitive layer 74. The setting of the first light-shielding area 1011 can widen the spacing of the first opening area 1012, ensuring that light from different point light sources 72 can be distinguished, so that multiple point light sources at a relatively close distance can be lit at the same time, ensuring that the light from point light sources emitted at different positions does not interfere with each other. Finally, the image formed by each point light source can be restored through a software algorithm, thereby splicing a large-area fingerprint image.

[0074] Furthermore, in order to reduce the incidence of stray light, the optical layer 73 may further include a second light shielding layer 91 disposed on the side of the first light shielding layer 81 away from the base substrate 71, as shown in FIG. Figure 9 The cross-sectional structure diagram of the first light-shielding layer and the second light-shielding layer is shown. Figure 11 Schematic diagram of the planar structure of the second light-shielding layer is shown. The second light-shielding layer 91 includes a plurality of second light-shielding units 111 . Each second light-shielding unit 111 includes a second light-shielding area 1111 and a second opening area 1112 .

[0075] Similarly, to ensure that the range of images formed by light emitted from point light sources at different locations, after passing through the first light-shielding layer 81 and incident on the photosensitive layer 74, is consistent, the relative positions of the second light-shielding units 111 and the photosensitive units 741 can be fixed. For example, the orthographic projection of the second light-shielding area 1111 on the photosensitive layer 74 covers a second predetermined number of photosensitive units 741, and the orthographic projection of the second opening area 1112 on the photosensitive layer 74 covers a first predetermined number of photosensitive units 741.

[0076] Figure 11 The first preset number shown in FIG is 8, and the second preset number is 1. Figure 11The orthographic projection of each second light-shielding unit 111 on the photosensitive layer 74 covers 3*3 photosensitive units 741 (as shown by the dotted line); the orthographic projection of the second opening area 1112 on the photosensitive layer 74 covers 8 photosensitive units 741; the orthographic projection of the second light-shielding area 1111 on the photosensitive layer 74 covers 1 photosensitive unit 741 and is located at the center of the second light-shielding unit 111. The shape of the second light-shielding area 1111 can be the same as that of the photosensitive unit 741, for example, a square.

[0077] When the optical layer 73 includes the first light shielding layer 81 and the second light shielding layer 91, in order to ensure that as much effective imaging light as possible is incident on the photosensitive layer 74, and at the same time ensure that the light emitted by the point light sources 72 at multiple positions is incident on different photosensitive units 741 respectively, Figure 9 The sizes of the first light-shielding layer 81 and the second light-shielding layer 91 can satisfy the following formula: (a+b / 2)>2.7(h1+h2), wherein a is the side length of the first opening area 1012, b is the interval width between two adjacent first opening areas 1012, h1 is the distance between the first light-shielding layer 81 and the second light-shielding layer 91, and h2 is the distance between the second light-shielding layer 91 and the photosensitive layer 74. This can ensure that light from different point light sources is not mixed.

[0078] To further reduce stray light, refer to Figure 9 , the orthographic projection of the second light-shielding area 1111 on the photosensitive layer 74 can cover the orthographic projection of the first opening area 1012 on the photosensitive layer 74 (c>a), and at the same time, the orthographic projection of the second light-shielding area 1111 on the photosensitive layer 74 can cover a photosensitive unit (c>d), and the sizes of the first light-shielding layer 81 and the second light-shielding layer 91 can further satisfy the following formula: (ca)<0.9h1, and c<2.7h1, where c is the side length of the second light-shielding area 1111.

[0079] In a specific implementation, the orthographic projection of the second light-shielding area 1111 on the photosensitive layer 74 can completely overlap with the orthographic projection of the first opening area 1012 on the photosensitive layer 74 and the photosensitive unit 741 (i.e., a=c=d). The shape of the second light-shielding area 1111 can be a square, and the dimensions of the first light-shielding layer 81 and the second light-shielding layer 91 can satisfy the following formula: b=2a, 0.37a≤h1<0.74a, 0≤h2

[0080] ​By disposing a first light-shielding layer 81 and a second light-shielding layer 91 between the substrate 71 and the photosensitive layer 74, and rationally sizing the first light-shielding region 1011, the first aperture region 1012, the second light-shielding region 1111, and the second aperture region 1112, it is possible to ensure that only light within a specific range of incident angles passes through the first light-shielding layer 81 and enters the photosensitive layer 74. The provision of the first light-shielding region 1011 widens the spacing between the first aperture regions 1012, ensuring that light from different point light sources 72 can be distinguished, while also reducing stray light intake and improving imaging quality. It should be noted that the second light-shielding layer 91 is not required. In applications where stray light is less critical, the second light-shielding layer 91 can be omitted or formed directly on the photosensitive layer 74 (i.e., h2 = 0).

[0081] In another optional implementation, refer to Figure 12 , the optical layer 73 may include a plurality of micro lens units 121 , that is, the optical layer 73 is a micro lens array.

[0082] Similarly, in order to ensure that the range of images formed by light emitted from point light sources at different locations is consistent when incident on the photosensitive layer 74 after passing through the microlens array, the relative positions of the microlens units 121 and the photosensitive units 741 can be fixed. For example, the orthographic projection of each microlens unit 121 on the photosensitive layer 74 covers a third predetermined number of photosensitive units 741, and the third predetermined number can be greater than 1.

[0083] In a specific implementation, a microlens array can be laminated beneath the OLED, and a photosensitive layer 74 can be laminated beneath the microlens array, with an air layer between the microlens array and the photosensitive layer 74. The microlens units 121 converge parallel light, distinguishing light incident from different angles and preventing light from different point sources from mixing. Because the microlens array's aperture ratio for light is much greater than that of the aforementioned light-shielding layer, using a microlens array as an optical layer can achieve a higher signal-to-noise ratio.

[0084] The fingerprint recognition substrate provided in the embodiment of the present application can simultaneously illuminate multiple point light sources that are close to each other. The arrangement rules of these point light sources need to ensure that the imaging light of each point light source on the image side can be distinguished, which requires ensuring that the non-imaging area of ​​each point light source is tangent to the image side. By illuminating multiple point light sources according to this arrangement rule, a more compact object-side image and image-side image can be obtained. Figure 13 It shows the original object relationship diagram without the optical layer. Figure 14 The schematic diagram of the relationship between the objects and images in the optical layer is shown. Figure 14 The object space image and image space image in are more dense.

[0085] Reference Figure 15The figure shows the simulation effect of four point light sources forming images at the same time. During the simulation, the light from the point light sources at different positions is represented by different colors. From the local enlarged figure, it can be seen that there is no light mixing between the point light sources at different positions.

[0086] Another embodiment of the present application further provides a fingerprint recognition device, which includes the fingerprint recognition substrate described in any embodiment.

[0087] It should be noted that the fingerprint recognition device in this embodiment can be a product or component such as a display panel, electronic paper, a mobile phone, a tablet computer, a television, a laptop computer, a digital photo frame, or a navigator.

[0088] Another embodiment of the present application further provides a fingerprint recognition method, which is applied to the fingerprint recognition substrate described in any embodiment, referring to Figure 17 and Figure 18 , the fingerprint recognition method may include:

[0089] Step 1701: When a finger is detected touching the fingerprint recognition substrate, multiple point light sources within the touch area are illuminated.

[0090] In a specific implementation, the fingerprint image of each point light source includes a non-imaging area. Multiple point light sources within the touch area can be illuminated according to a preset arrangement rule, where the preset arrangement rule circumscribes the non-imaging area of ​​each point light source. Lighting multiple point light sources according to this arrangement rule can produce a more compact object-side image and image-side image.

[0091] Step 1702: Generate an initial fingerprint image according to the fingerprint electrical signal of the photosensitive unit, wherein the fingerprint electrical signal is generated by the photosensitive unit according to the received signal light.

[0092] Reference Figure 16 The schematic diagram of imaging of a simulated finger pressing a fingerprint recognition substrate is shown. It can be seen from the figure that the fingerprint image obtained by direct imaging is in an aliasing state. The initial fingerprint image needs to be processed to obtain the target fingerprint image.

[0093] Step 1703: extracting the fingerprint image of each point light source from the initial fingerprint image according to the correspondence between each point light source and the photosensitive unit.

[0094] Because the signal light from each point light source enters a different photosensitive unit after passing through the optical layer, the final photosensitive unit can be determined based on the position of the point light source and the propagation path of the signal light, thereby obtaining a correspondence between the point light source and the photosensitive unit. Based on this correspondence between the point light source and the photosensitive unit, the fingerprint image of each point light source can be extracted from the initial fingerprint image.

[0095] Step 1704: Perform uniform processing on the fingerprint image of each point light source.

[0096] In an optional implementation method, this step may specifically include: first, using a pre-calibrated standard brightness distribution to perform brightness correction on the fingerprint image of each point light source; in the fingerprint image of each point light source after the brightness correction, the brightness of each photosensitive unit in the photosensitive area is summed, and the summation result is used as the brightness of the photosensitive area, wherein the photosensitive area includes the photosensitive unit covered by the positive projection of the first shading unit on the photosensitive layer.

[0097] In a specific implementation, when a finger is detected pressing the fingerprint recognition substrate, multiple point light sources are simultaneously illuminated according to a preset arrangement rule to obtain an initial fingerprint image; then, the center of the imaging of each point light source in the initial fingerprint image (i.e., the center of the non-dark area) is located, and with this center position as a reference, Rmax photosensitive units are extrapolated up, down, left, and right (Rmax is the maximum radius that a single point light source can image) to form a rectangle. The initial fingerprint image is cropped according to the rectangular area, and based on the correspondence between each point light source and the photosensitive unit, the fingerprint image Icrop_n of each point light source can be extracted. The fingerprint image Icrop_n(i, j) of each point light source is brightness corrected using the pre-calibrated standard brightness distribution Istandard(i, j). The correction formula is as follows:

[0098]

[0099] Where Vmax is the maximum value of the system's collected signal. For example, if the system is a 16-bit acquisition system, Vmax is 65535. Thresh is the threshold for determining whether the brightness signal in the standard brightness distribution is valid. Brightness correction can make the brightness of the fingerprint image of each point light source more uniform.

[0100] Then, the brightness signals in the fingerprint image of each point light source after brightness correction are accumulated. This accumulation method is to sum the brightness of each photosensitive unit in the photosensitive area, and use the summed result as the brightness of the photosensitive area, thereby obtaining a low-resolution fingerprint image. The photosensitive area corresponds to the first light-shielding unit and includes the photosensitive units covered by the orthographic projection of the first light-shielding unit on the photosensitive layer.

[0101] For example, in Figure 10 In the embodiment, the photosensitive area corresponding to the first light-shielding unit includes 9 photosensitive units, and the brightness of the 9 photosensitive units can be summed to obtain the brightness value of the corresponding photosensitive area.

[0102] Step 1705: stitching the fingerprint images of the point light sources after the homogenization process to obtain the target fingerprint image.

[0103] When the fingerprint images of the point light sources overlap, the brightness of the fingerprint images of the point light sources located in the same photosensitive area within the overlapping area is averaged or weighted summed to obtain the brightness of the target fingerprint image in the same photosensitive area. The weight value of each point light source in the weighted summation can be determined based on the distance between the same photosensitive area and each point light source.

[0104] In an optional implementation, the steps for pre-calibrating to obtain a standard brightness distribution are as follows: first, in a dark room, light up the point light sources at different positions in turn; obtain the original image of each point light source based on the calibration electrical signal of the photosensitive unit, wherein the calibration electrical signal is generated by the photosensitive unit based on the received signal light; then, average the brightness of the sensing units with the same relative position in the original images of all point light sources to obtain a standard brightness distribution, where the relative position is the position of the sensing unit relative to the corresponding point light source.

[0105] In a specific implementation, the imaging system can be placed in a darkroom and point light sources at different positions are sequentially illuminated. Each time a point light source is illuminated, the center position of the point light source is located on the image captured by the photosensitive layer sensor. Using this position as a reference, Rmax photosensitive units are extrapolated up, down, left, and right (Rmax is the maximum radius that a single point light source can image) to form a rectangle. The original image captured each time is cropped with this rectangle to form a series of equal-sized and similar images. Then, the brightness of these images is averaged, that is, the brightness of the photosensitive units in the same position relative to the point light source in these images is averaged to obtain the brightness distribution of the single point light source imaged on each photosensitive unit, that is, the standard brightness distribution Istandard.

[0106] The fingerprint recognition method provided in this embodiment first extracts the fingerprint images of each point light source from the initial fingerprint image, then performs brightness correction and superposition processing on the fingerprint images of each point light source, and then splices the fingerprint images of each point light source after superposition processing, so as to achieve a single imaging to obtain a large and dense fingerprint image (such as Figure 18 As shown), the fingerprint recognition efficiency is improved and the scene requirements with high real-time requirements for fingerprint recognition are met.

[0107] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0108] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device that includes a series of elements includes not only those elements, but also other elements that are not explicitly listed, or also includes elements that are inherent to such process, method, commodity or device. In the absence of further restrictions, an element defined by the statement "comprises a..." does not exclude the presence of other identical elements in the process, method, commodity or device that includes the element.

[0109] The above is a detailed introduction to a fingerprint recognition substrate, a fingerprint recognition method, and a display device provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A fingerprint recognition substrate, characterized in that: The fingerprint recognition substrate includes: A substrate; A plurality of point light sources disposed on one side of the substrate, each of the point light sources being configured to emit signal light; An optical layer and a photosensitive layer stacked on the side of the substrate facing away from the point light sources, the optical layer being disposed close to the substrate, the photosensitive layer including a plurality of photosensitive units, the optical layer being configured to incident the signal light of each of the point light sources reflected by a finger to different photosensitive units, and each of the photosensitive units being configured to receive the signal light emitted by the optical layer for fingerprint recognition; The optical layer includes a first light-shielding layer, the first light-shielding layer including a plurality of first light-shielding units, each of the first light-shielding units including a first light-shielding region and a first opening region, the positive projection of the first light-shielding region on the photosensitive layer covering a first preset number of photosensitive units, and the positive projection of the first opening region on the photosensitive layer covering a second preset number of photosensitive units; The optical layer further includes a second light-shielding layer disposed on the side of the first light-shielding layer facing away from the substrate, the second light-shielding layer including a plurality of second light-shielding units, each of the second light-shielding units including a second light-shielding region and a second opening region, the positive projection of the second light-shielding region on the photosensitive layer covering the second preset number of photosensitive units, and the positive projection of the second opening region on the photosensitive layer covering the first preset number of photosensitive units.

2. The fingerprint recognition substrate according to claim 1, characterized in that: The shape of the first opening region is square, and the size of the first light-shielding layer satisfies the following formula: (a + b / 2) > 2.7h1, where a is the side length of the first opening region, b is the interval width between two adjacent first opening regions, and h1 is the distance between the first light-shielding layer and the photosensitive layer.

3. The fingerprint recognition substrate according to claim 1, characterized in that: The shape of the first opening region is square, and the sizes of the first light-shielding layer and the second light-shielding layer satisfy the following formula: (a + b / 2) > 2.7(h1 + h2), where a is the side length of the first opening region, b is the interval width between two adjacent first opening regions, h1 is the distance between the first light-shielding layer and the second light-shielding layer, and h2 is the distance between the second light-shielding layer and the photosensitive layer.

4. The fingerprint recognition substrate according to claim 3, characterized in that: The positive projection of the second light-shielding region on the photosensitive layer covers the positive projection of the first opening region on the photosensitive layer, the shape of the second light-shielding region is square, and the sizes of the first light-shielding layer and the second light-shielding layer satisfy the following formula: (c - a) < 0.9h1, and c < 2.7h1, where c is the side length of the second light-shielding region.

5. The fingerprint recognition substrate according to claim 3, characterized in that: The positive projection of the second light-shielding region on the photosensitive layer completely overlaps with the positive projection of the first opening region on the photosensitive layer and the photosensitive units respectively, the shape of the second light-shielding region is square, and the sizes of the first light-shielding layer and the second light-shielding layer satisfy the following formula: b = 2a, 0.37a ≤ h1 < 0.74a, 0 ≤ h2 < h1, where c is the side length of the second light-shielding region.

6. The fingerprint recognition substrate according to claim 1, characterized in that: The optical layer includes a plurality of microlens units, and the orthographic projection of each of the microlens units on the photosensitive layer covers a third preset number of photosensitive units, where the third preset number is greater than 1.

7. A fingerprint recognition device, characterized in that: The fingerprint recognition device comprises the fingerprint recognition substrate according to any one of claims 1 to 6.

8. A fingerprint recognition method, characterized in that: Applied to the fingerprint recognition substrate according to any one of claims 1 to 6, the method comprising: When a finger is detected touching the fingerprint recognition substrate, a plurality of point light sources in the touch area are illuminated; Generate an initial fingerprint image according to the fingerprint electrical signal of the photosensitive unit, wherein the fingerprint electrical signal is generated by the photosensitive unit according to the received signal light; Extracting the fingerprint image of each of the point light sources from the initial fingerprint image according to the corresponding relationship between each of the point light sources and the photosensitive unit; Performing homogenization processing on the fingerprint images of each of the point light sources; The fingerprint images of the point light sources after the homogenization process are spliced ​​to obtain a target fingerprint image.

9. The fingerprint recognition method according to claim 8, characterized in that: The fingerprint image of each point light source includes a non-imaging area, and the step of lighting up the plurality of point light sources in the touch area includes: The plurality of point light sources within the touch area are lit according to a preset arrangement rule, wherein the preset arrangement rule is that the non-imaging area of ​​each point light source is circumscribed.

10. The fingerprint recognition method according to claim 8, characterized in that: The step of homogenizing the fingerprint images of the point light sources comprises: Using a pre-calibrated standard brightness distribution, the fingerprint image of each point light source is subjected to brightness correction; In the fingerprint image of each point light source after brightness correction, the brightness of each photosensitive unit in the photosensitive area is summed, and the summed result is used as the brightness of the photosensitive area, wherein the photosensitive area includes the photosensitive unit covered by the orthographic projection of the first light shielding unit on the photosensitive layer; The step of stitching the fingerprint images of the point light sources after the homogenization process is completed comprises: When the fingerprint images of the point light sources have overlapping areas, the brightness of the fingerprint images of the point light sources in the same photosensitive area in the overlapping area is averaged or weighted summed to obtain the brightness of the target fingerprint image in the same photosensitive area.

11. The fingerprint recognition method according to claim 10, characterized in that: Before the step of using the pre-calibrated standard brightness distribution to perform brightness correction on the fingerprint image of each of the point light sources, the method further includes: In a dark room, light up point light sources at different positions one by one; Obtaining an original image of each of the point light sources according to a calibration electrical signal of the photosensitive unit, wherein the calibration electrical signal is generated by the photosensitive unit according to the received signal light; The brightness of the sensing units at the same relative position in the original images of all the point light sources is averaged to obtain the standard brightness distribution, where the relative position is the position of the sensing unit relative to the corresponding point light source.

Images