Optical lens, optical fingerprint acquisition module and electronic equipment

Abstract

The invention provides an optical lens, an optical fingerprint acquisition module and electronic equipment, relates to the technical field of biological recognition, is applied to a fingerprint recognition scene, and realizes that the light transmittance of a light-transmitting element corresponding to a central area is smaller than the light transmittance of a light-transmitting element corresponding to a peripheral area by arranging an adjusting film on a light-transmitting substrate. When the optical lens where the light-transmitting element is located is arranged in the reflection light path, light energy in the middle position of an image can be reduced by means of the low light transmittance of the central area, and light energy in the edge position of the image can be maintained or even improved by means of the high light transmittance of the peripheral area. Therefore, the light energy difference between the middle position and the edge position of the image can be reduced, and the relative illumination of the image is improved. Moreover, during imaging, due to the reduction of the light energy in the middle of the image, the appropriate exposure time can be prolonged, so that the edge position of the image can record more biological characteristic information, and the biological recognition accuracy is improved.

Description

Technical Field

[0001] This application relates to the field of biometric information acquisition technology, and more specifically, to an optical lens, an optical fingerprint acquisition module, and an electronic device. Background Technology

[0002] With the development of portable terminal devices, such as mobile phones, the application of biometric technology is becoming increasingly widespread and in-depth. Taking electronic devices as an example, fingerprint recognition, fingerprint verification, and facial recognition are increasingly used in screen wake-up of display devices and identity authentication steps in various programs, improving the security of display devices and the flexibility of their use.

[0003] When a fingerprint module integrated under the display screen uses a lens-based imaging solution, there is a significant difference in brightness between the image edges and the center, resulting in lower edge brightness and higher center brightness, leading to lower relative illumination. As display resolution increases (to improve display quality) and the wide-angle capabilities of lenses are applied (to expand the fingerprint collection area), the edge brightness of the image will further decrease, making it difficult to meet the requirements for fingerprint recognition. Summary of the Invention

[0004] The purpose of this application is to address the shortcomings of the prior art by providing an optical lens, an optical fingerprint acquisition module, and an electronic device.

[0005] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows: In one aspect of this application, an optical lens is provided, the optical lens including a first lens and a light-transmitting element disposed in a reflective light path, the reflective light path being formed from reflected light from a fingerprint; The light-transmitting element includes a light-transmitting substrate and a conditioning film; The optical surface of at least one side of the light-transmitting substrate includes a central region and a peripheral region surrounding the central region. An adjustment membrane is provided in the central area and / or at least one peripheral area to adjust the light transmittance of the light-transmitting element in the central area to be less than the light transmittance of the light-transmitting element in the peripheral area.

[0006] Optionally, an adjustment membrane is provided in each peripheral area, the number of adjustment membranes being equal to the number of peripheral areas, and the adjustment membranes being antireflective membranes; Alternatively, an adjustment membrane can be installed in the central area, with one adjustment membrane, which is a light-blocking membrane.

[0007] Optionally, an adjustment membrane may be provided in the central area and each of the peripheral areas; The regulating film located in the central area is an anti-reflective film, and the regulating film located in the peripheral area is an anti-reflective film, and the light transmittance of the regulating film located in the central area is less than the light transmittance of the regulating film located in the peripheral area; or, the regulating film located in the central area is a light-blocking film, and the regulating film located in the peripheral area is an anti-reflective film.

[0008] Optionally, the regulating film located in the central area is a light-shielding film, and the regulating film located in the peripheral area is an anti-reflection film; The optical surface also includes a non-coated area located between the central region and the peripheral region, where no adjustment film is provided.

[0009] Optionally, when there are at least two peripheral areas and an adjustment film is provided in each peripheral area, the light transmittance of the adjustment film gradually increases along the direction from the center to the edge of the light-transmitting substrate.

[0010] Optionally, the antireflective coating includes alternating and stacked high-refractive-index layers and low-refractive-index layers, and the light transmittance of the antireflective coating is positively correlated with the total number of high-refractive-index layers and low-refractive-index layers contained in the antireflective coating.

[0011] Optionally, the optical surface of at least one side of the light-transmitting substrate is planar; Alternatively, the optical surface of at least one side of the light-transmitting substrate may be convex or concave along the optical axis of the light-transmitting element.

[0012] Optionally, the orthographic projection of the central region along the optical axis of the light-transmitting element is a circle, and the orthographic projection of the peripheral region along the optical axis of the light-transmitting element is an annulus.

[0013] Optionally, the optical lens also includes an aperture stop, and an adjustment film is disposed on the optical surface of the light-transmitting element on the side away from the aperture stop.

[0014] Optionally, the light-transmitting element is a second lens.

[0015] Optionally, the area of ​​the optical surface of the light-transmitting element is greater than the area of ​​the light-incident or light-excising surface of any first lens.

[0016] In another aspect of this application, an optical fingerprint acquisition module is provided, including an image sensor and an optical lens of any of the above-mentioned types. The optical lens is located on the receiving side of the image sensor, and reflected light from the fingerprint is incident on the image sensor after passing through the optical lens.

[0017] In another aspect of this application, an electronic device is provided, including a display screen and an optical fingerprint acquisition module as described above, wherein the optical fingerprint acquisition module is located below the display screen.

[0018] The beneficial effects of this application include: This application provides an optical lens, an optical fingerprint acquisition module, and an electronic device applied in fingerprint recognition scenarios. In these scenarios, the light transmittance differs between areas on a light-transmitting substrate with and without an adjustment film, and / or, different areas on the light-transmitting substrate with adjustment films also exhibit differences in light transmittance due to variations in the films themselves. Based on this, by setting an adjustment film on the light-transmitting substrate, the light transmittance of the central region of the light-transmitting element is made lower than that of the peripheral region, thus creating a differentiated light transmittance setting between the central and peripheral regions. Utilizing this differentiated setting, when the optical lens containing the light-transmitting element is applied to the reflected light path of fingerprint acquisition, the lower light transmittance in the central region reduces the light energy at the center of the image, while the higher light transmittance in the peripheral region maintains or even increases the light energy at the image edges. This reduces the difference in light energy between the center and edges of the image, thereby improving the relative illumination of the image. Furthermore, during imaging, the reduced light energy in the center of the image allows for a suitable increase in exposure time, which in turn helps to record more biometric information at the edges of the image, facilitating the extraction of biometric information and improving the accuracy of biometric identification. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is one of the structural schematic diagrams of a light-transmitting element provided in an embodiment of this application; Figure 2 This is a schematic diagram of a light-transmitting element applied to a reflected light path, provided in an embodiment of this application. Figure 3 This is a second schematic diagram of the structure of a light-transmitting element provided in an embodiment of this application; Figure 4 This is the third schematic diagram of a light-transmitting element provided in the embodiments of this application; Figure 5 This is the fourth schematic diagram of a light-transmitting element provided in the embodiments of this application; Figure 6 for Figure 4 Cross-sectional view of AA in the middle; Figure 7 This is a comparison of the relative illumination of the images formed on the photosensitive surface by the two methods; Figure 8This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application.

[0021] Icons: 100 - Light-transmitting element; 110 - Light-transmitting substrate; 101 - Central area; 102 - Peripheral area; 103 - Non-coated area; 11 - Light rays with a smaller field of view; 12 - Light rays with a larger field of view; 121 - Anti-reflective coating; 122 - Light-shielding coating; 1211 - High refractive index layer; 1212 - Low refractive index layer; 20 - Optical fingerprint acquisition module; 21 - Optical lens. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] As display resolution increases, it negatively impacts light transmittance, particularly affecting light rays that would otherwise be incident on the image edges, resulting in increased obstruction and reduced edge brightness. It should be understood that the initial edge brightness was already at a level where extracting biometric information was difficult; further reduction increases the difficulty of extracting this information. Therefore, increasing display resolution significantly reduces image edge brightness, potentially worsening the image's relative illumination.

[0024] Driven by the need to expand the fingerprint collection area to improve user experience, a wide-angle lens was incorporated. However, it should be understood that a wide-angle lens results in greater attenuation of light incident on the image edges. This reduced edge brightness increases the difficulty of extracting biometric information, and when combined with other factors, it may even prevent the extraction of biometric information from the image edges altogether. Therefore, the use of a wide-angle lens reduces the edge brightness of the image, which may further worsen the image's relative illumination.

[0025] In view of this, one aspect of the embodiments of this application provides a light-transmitting element, wherein the optical lens includes a first lens and a light-transmitting element sequentially disposed in a reflected light path, the reflected light path being formed from reflected light from a fingerprint; the light-transmitting element includes a light-transmitting substrate and an adjustment film; the optical surface of at least one side of the light-transmitting substrate includes a central region and a peripheral region surrounding the central region; the adjustment film is disposed in the central region and / or at least one peripheral region to adjust the light transmittance of the light-transmitting element corresponding to the central region to be less than the light transmittance in the peripheral region.

[0026] The areas on the light-transmitting substrate with and without adjustment films will have different light transmittance due to the adjustment films, and / or different areas on the light-transmitting substrate with adjustment films will also have different light transmittance due to the different adjustment films. Based on this, by setting an unlimited number of adjustment films on the light-transmitting substrate, the light transmittance of the central area of ​​the light-transmitting element can be made lower than that of the peripheral area, thus creating a differentiated light transmittance setting between the central and peripheral areas of the light-transmitting element. Using this differentiated setting, when the optical lens containing the light-transmitting element is applied to the reflected light path of fingerprint acquisition, the lower light transmittance in the central area reduces the light energy in the center of the image, while the higher light transmittance in the peripheral area maintains or even increases the light energy at the image edges. This reduces the difference in light energy between the center and edges of the image, improving the relative illumination of the image. Furthermore, when using the optical lens for imaging, the reduced light energy in the center of the image allows for a longer exposure time, which helps to record more biometric information at the edges of the image, facilitating the extraction of biometric information and improving the accuracy of biometric identification.

[0027] Figure 1 This is a schematic diagram of the structure of a light-transmitting element provided in an embodiment of this application. Figure 1 The optical surface of one side of the light-transmitting element 100 is shown in the figure. Figure 2 for Figure 1 An example of the light-transmitting element 100 being used in a reflected light path.

[0028] The light-transmitting element 100 can be divided into a central region 101 and an unlimited number of peripheral regions 102. The peripheral regions 102 are located around the central region 101, surrounding the outer side of the central region 101. Thus, the central region 101 and the peripheral regions 102 can be arranged sequentially from the center to the edge of the light-transmitting element 100. Figure 1 In this context, a single peripheral region 102 surrounds the outer side of the central region 101; for example... Figure 3 As shown, multiple peripheral regions 102 are nested around the central region 101. The light transmittance of the light-transmitting element 100 corresponding to the central region 101 is less than the light transmittance of the light-transmitting element 100 corresponding to the peripheral regions 102.

[0029] To facilitate understanding, the application of the light-transmitting element 100 to the reflected light path will be explained: Please refer to the reference. Figure 2When the light-transmitting element 100 is placed in the reflected light path, a photosensitive surface L5 of the image sensor is provided on its light-emitting side. In this way, the incident light can pass through the light-transmitting element 100 before entering the image sensor. It should be understood that the middle position of the photosensitive surface L5 is the middle position of the image formed by the image sensor, and the edge position of the photosensitive surface L5 is the edge position of the image formed by the image sensor.

[0030] Light ray 11, with a smaller field of view (smaller angle between the ray and the optical axis), is usually incident on the center of the photosensitive surface L5 after lens adjustment. Light ray 12, with a larger field of view (larger angle between the ray and the optical axis), is usually incident on the edge of the photosensitive surface L5 after lens adjustment. (Continue referring to...) Figure 2 By utilizing the lower light transmittance of the light-transmitting element 100 corresponding to the central region 101, light rays 11 with a smaller field of view can penetrate the central region 101 with lower transmittance and ultimately incident on the center position of the photosensitive surface L5, thus reducing the light energy at the center of the image. Conversely, by utilizing the higher light transmittance of the light-transmitting element 100 corresponding to the peripheral region 102, light rays 12 with a larger field of view can penetrate the peripheral region 102 with higher transmittance and ultimately incident on the edge position of the photosensitive surface L5, thus maintaining or increasing the light energy at the image edge position. Based on this, the difference in light energy between the center and edge positions of the image can be reduced, improving the relative illumination of the image. Furthermore, during imaging, the reduced light energy at the center position allows for a longer exposure time, enabling more light to incident on the image edge positions. This allows the edge positions to record more biometric information, facilitating the extraction of biometric information and improving the accuracy of biometric identification.

[0031] To achieve the difference in light transmittance between the central region 101 and the peripheral region 102 of the light-transmitting element 100, an adjustment film can be deposited, which will be described below: Please continue to refer to Figure 1 The light-transmitting element 100 includes a light-transmitting substrate 110 and a regulating film ( Figure 1 (not shown in the image) The light-transmitting substrate 110 can serve as a structure to support the adjustment film. Therefore, the adjustment film can be disposed on at least one optical surface of the light-transmitting substrate 110, such as on one optical surface of the light-transmitting substrate 110, or on opposite optical surfaces of the light-transmitting substrate 110.

[0032] The light-transmitting substrate 110 has at least two optical surfaces. For example... Figure 2 In the light-transmitting substrate 110, the upper and lower surfaces are optical surfaces. The light-transmitting substrate 110 is made of a light-transmitting material, so when light enters from the optical surface on one side of the light-transmitting substrate 110, it can exit from the optical surface on the other side of the light-transmitting substrate 110.

[0033] When the central region 101 and the peripheral region 102 are focused on the optical surface of the light-transmitting substrate 110, at least one optical surface includes the aforementioned central region 101 and peripheral region 102. The central region 101 refers to the region through which the optical axis b passes, and the peripheral region 102 refers to the region located outside the central region 101. The central region 101 and the peripheral region 102 are arranged sequentially along direction a from the center to the edge of the light-transmitting substrate 110. For example... Figure 1 In the optical surface, a central region 101 and a peripheral region 102 are divided, and the central region 101 and the peripheral region 102 are arranged sequentially along the direction a from the center to the edge of the light-transmitting substrate 110.

[0034] The number of adjusting films should be set reasonably according to the needs, such as one, two, three, etc. The adjusting film can adjust the overall light transmittance of the light-transmitting element 100 at its location. For example, the light transmittance will differ between areas on the light-transmitting substrate 110 where the adjusting film is installed (which can be the central area 101 or the peripheral area 102) and areas without adjusting films (which can also be the central area 101 or the peripheral area 102). Different areas on the light-transmitting substrate 110 where adjusting films are installed (which can be the central area 101 and the peripheral area 102, or the peripheral area 102 and the peripheral area 102) will also have different light transmittance due to the different adjusting films.

[0035] Therefore, by providing an adjustment film in the central region 101 and / or at least one peripheral region 102, the light transmittance of the light-transmitting element 100 corresponding to the central region 101 can be made lower than the light transmittance of the light-transmitting element 100 corresponding to the peripheral region 102. For ease of understanding, the placement of the adjustment film will be schematically explained below with reference to the accompanying drawings: Optionally, an adjustment film is provided only in the peripheral region 102, and not in the central region 101. Specifically, the number of adjustment films is equal to the number of peripheral regions 102, with one adjustment film provided in each peripheral region 102. The adjustment film is an antireflective film 121. In this way, the light transmittance of the central region 101 without an adjustment film maintains the light transmittance of the light-transmitting substrate 110 itself, while the peripheral regions 102 with the antireflective film 121 can utilize the antireflective film 121 to increase the light transmittance of that region. This achieves a situation where the light transmittance of the light-transmitting element 100 corresponding to the central region 101 is less than the light transmittance of its corresponding peripheral region 102. For example... Figure 1The diagram shows a central region 101 and a peripheral region 102 surrounding the central region 101. The central region 101 does not have an adjustment film, while the peripheral region 102 has an anti-reflection film 121. This anti-reflection film 121 allows the light transmittance of the light-transmitting element 100 corresponding to the central region 101 to be less than the light transmittance of its corresponding peripheral region 102. For example... Figure 3 The image shows a central region 101 and two peripheral regions 102 surrounding the central region 101. The central region 101 is not provided with an adjustment film, but only the two peripheral regions 102 are provided with anti-reflection films 121. In this way, the anti-reflection films 121 can make the light transmittance of the light-transmitting element 100 corresponding to the central region 101 less than the light transmittance of its corresponding peripheral region 102.

[0036] It should be understood that when there are two or more instances of the number 102 in the surrounding area, it can be referred to... Figure 1 and Figure 3 Reasonable settings are made. For example, in some optional embodiments, when the antireflective film 121 is provided only in the peripheral area 102, and the number of adjustment films and peripheral areas 102 is at least two, the light transmittance of the adjustment film gradually increases along the direction from the center to the edge of the light-transmitting substrate 110. That is, the light transmittance of the light-transmitting element 100 is different for different peripheral areas 102, and generally shows a trend of gradually increasing light transmittance from the center to the edge. This allows for multi-region adjustment of the light energy in the direction from the center to the edge of the image, thereby improving the relative illumination of the image.

[0037] Optionally, an adjustment film is provided only in the central region 101, and no adjustment film is provided in the peripheral region 102. Specifically, an adjustment film is provided in the central region 101, and the number of adjustment films is one, which is a light-shielding film 122. In this way, the light transmittance of the peripheral region 102 without the adjustment film remains the same as that of the light-transmitting substrate 110 itself, while the central region 101 with the light-shielding film 122 can reduce the light transmittance of that region by utilizing the light-blocking property of the light-shielding film 122, so that the light transmittance of the light-transmitting element 100 corresponding to the central region 101 is less than the light transmittance of its corresponding peripheral region 102. For example Figure 1 The diagram shows a central region 101 and a peripheral region 102 surrounding the central region 101. A light-shielding film 122 is provided only in the central region 101, while no adjusting film is provided in the peripheral region 102. This allows the light-shielding film 122 to ensure that the light transmittance of the light-transmitting element 100 corresponding to the central region 101 is less than the light transmittance of its corresponding peripheral region 102. It should be understood that when there are two or more peripheral regions 102, reference can be made to... Figure 1 Configure it appropriately.

[0038] Optionally, an adjustment film is provided in both the central region 101 and each peripheral region 102, and all adjustment films are antireflective films 121. Specifically, the adjustment film located in the central region 101 is an antireflective film 121, and the adjustment film located in the peripheral region 102 is an antireflective film 121. The light transmittance of the adjustment film located in the central region 101 is less than the light transmittance of the adjustment film located in the peripheral region 102, so that the light transmittance of the light-transmitting element 100 corresponding to the central region 101 is less than the light transmittance of its corresponding peripheral region 102. For example... Figure 1 The diagram shows a central region 101 and a peripheral region 102 surrounding the central region 101. An antireflective film 121 is provided in the central region 101 and an antireflective film 121 is provided in the peripheral region 102. The light transmittance of the two antireflective films 121 is different. By utilizing the difference in the antireflective films 121, the light transmittance of the light-transmitting element 100 corresponding to the central region 101 is less than the light transmittance of its corresponding peripheral region 102.

[0039] It should be understood that when there are two or more instances of the number 102 in the surrounding area, it can be referred to... Figure 1 Reasonable settings are made. For example, in some optional embodiments, when there are two or more peripheral regions 102, and each peripheral region 102 is provided with an antireflective film 121, the light transmittance of the film gradually increases along the direction from the center to the edge of the light-transmitting substrate 110. That is, the light transmittance of the light-transmitting element 100 varies for different peripheral regions 102, and generally shows a trend of gradually increasing light transmittance from the center to the edge. This allows for multi-regional adjustment of the light energy from the center to the edge of the image, improving the relative illumination of the image. For example... Figure 4 The diagram shows a central region 101 and two peripheral regions 102 surrounding the central region 101. An antireflective film 121 is provided in the central region 101, and an antireflective film 121 is provided in each of the two peripheral regions 102. The light transmittance of these three antireflective films 121 is different. By utilizing the difference in the antireflective films 121, the light transmittance of the light-transmitting element 100 corresponding to the central region 101 is less than the light transmittance of its corresponding peripheral region 102.

[0040] Optionally, adjusting films are provided in the central region 101 and each peripheral region 102, with the adjusting film in the central region 101 being a light-shielding film 122 and the adjusting film in the peripheral regions 102 being an anti-reflection film 121. This ensures that the light transmittance of the light-transmitting element 100 corresponding to the central region 101 is less than the light transmittance of its corresponding peripheral region 102. For example... Figure 1The diagram shows a central region 101 and a peripheral region 102 surrounding the central region 101. A light-shielding film 122 is provided in the central region 101, and an anti-reflection film 121 is provided in the peripheral region 102. Since the light-shielding film 122 has a negative impact on light transmittance, while the anti-reflection film 121 has a positive impact on light transmittance, the difference between the anti-reflection film 121 and the light-shielding film 122 can be used to make the light transmittance of the light-transmitting element 100 corresponding to the central region 101 less than the light transmittance of its corresponding peripheral region 102.

[0041] It should be understood that when there are two or more instances of the number 102 in the surrounding area, it can be referred to... Figure 1 Configure it appropriately.

[0042] For example, in some optional embodiments, when the adjustment film in the central region 101 is a light-shielding film 122, the number of peripheral regions 102 is two or more, and each peripheral region 102 is provided with an anti-reflection film 121, the light transmittance of the adjustment film gradually increases along the direction from the center to the edge of the light-transmitting substrate 110. That is, the light transmittance of the light-transmitting element 100 is different in different peripheral regions 102, and generally shows a trend of gradually increasing light transmittance from the center to the edge. This enables multi-region adjustment of the light energy in the direction from the center to the edge of the image, thereby improving the relative illumination of the image.

[0043] For example, in some alternative implementations, such as Figure 5 As shown, when the adjusting film in the central region 101 is a light-shielding film 122, and each peripheral region 102 is provided with an anti-reflection film 121, the optical surface also includes a non-coated region 103 located between the central region 101 and all peripheral regions 102. No adjusting film is provided in the non-coated region 103. The non-coated region 103 maintains the light transmittance of the light-transmitting substrate 110. The central region 101 is located inside the non-coated region 103, and the light-shielding film 122 provided thereon reduces the light transmittance. The peripheral regions 102 are located outside the non-coated region 103, and the anti-reflection film 121 provided thereon increases the light transmittance.

[0044] In some alternative embodiments, the light-shielding film 122 may be a light-absorbing film, a reflective film, or a completely opaque film.

[0045] In some alternative embodiments, when an adjusting membrane is provided within the central region 101, the adjusting membrane may cover the entire area of ​​the central region 101, or it may only cover a portion of the central region 101. The same applies to the peripheral region 102, therefore, it will not be described further.

[0046] In some alternative implementations, such as Figure 6As shown, the antireflective coating 121 includes alternating and stacked high-refractive-index layers 1211 and low-refractive-index layers 1212. The light transmittance of the antireflective coating 121 is positively correlated with the total number of high-refractive-index layers 1211 and low-refractive-index layers 1212 contained in the antireflective coating 121. For example... Figure 6 In the central region 101, the antireflective coating 121 has the lowest light transmittance, so it contains only one high-refractive-index layer 1211 and one low-refractive-index layer 1212. The antireflective coating 121 in the peripheral region 102 adjacent to the central region 101 has intermediate light transmittance, so it contains two high-refractive-index layers 1211 and two low-refractive-index layers 1212. The antireflective coating 121 in the outermost peripheral region 102 has the highest light transmittance, so it contains three high-refractive-index layers 1211 and three low-refractive-index layers 1212. It should be understood that when there are multiple high-refractive-index layers 1211 and low-refractive-index layers 1212, the heights of the high-refractive-index layers 1211 and the heights of the low-refractive-index layers 1212 can be different.

[0047] Optionally, the optical surfaces on both sides of the light-transmitting substrate 110 are planar, so that the light-transmitting substrate 110 does not have a converging or diverging effect on incident light.

[0048] Optionally, when the optical surface of one side of the light-transmitting substrate 110 is flat and the other side is convex or concave along the optical axis of the light-transmitting element 100, it can have a certain converging or diverging effect on the incident light.

[0049] Optionally, when the optical surfaces on both sides of the light-transmitting substrate 110 are convex or concave along the optical axis of the light-transmitting element 100, they can have a certain converging or diverging effect on the incident light.

[0050] When the optical surface of at least one side of the light-transmitting substrate 110 is convex or concave along the optical axis of the light-transmitting element 100, it can serve as a second lens in an optical lens.

[0051] like Figure 7 As shown, a comparison diagram of the relative illumination of images formed on the photosensitive surface L5 using two different schemes is presented. The two schemes include a scheme without the light-transmitting element 100 of this application in the reflected light path (corresponding to the relative illumination distribution before optimization) and a scheme with the light-transmitting element 100 of this application in the reflected light path (corresponding to the relative illumination distribution after optimization). Figure 7 It can be clearly seen that the larger the field of view, the closer the light is to the edge of the light-transmitting substrate. The light transmittance of the central area corresponding to the large field of view is less than that of the peripheral area corresponding to the small field of view. The optimized relative illumination is significantly improved.

[0052] Optionally, the shapes of the central area 101 and the surrounding area 102 can be reasonably selected according to actual needs. For example... Figure 1 In the image, the orthographic projection of the central region 101 along the optical axis of the light-transmitting element is a circle, and the orthographic projection of the peripheral region 102 along the optical axis of the light-transmitting element is an annulus. This can achieve better results when optimizing the relative illumination of the image.

[0053] In another aspect of the embodiments of this application, an optical lens is provided, the optical lens including a first lens disposed in a reflective light path and a light-transmitting element, the reflective light path being formed from reflected light from a fingerprint; wherein, the light-transmitting element is the aforementioned light-transmitting element.

[0054] like Figure 8 An optical lens 21 is shown. When the optical lens 21 is positioned in the reflected light path, reflected light from a fingerprint is transmitted through a first lens and a light-transmitting element (the order of the first lens and the light-transmitting element in the reflected light path is not restricted). The first lens can optically modulate the reflected light (e.g., convergence, divergence), while the light-transmitting element has the aforementioned optical characteristics: the light transmittance in the central region of the light-transmitting element is lower than that in the peripheral region. Based on this, the optical lens, by utilizing the optical characteristics of the light-transmitting element, can reduce the light energy in the center of the image and maintain or even increase the light energy at the edge of the image during imaging, thereby reducing the light energy difference between the center and edge of the image and improving the relative illumination of the image. Furthermore, due to the reduction in light energy in the center of the image, a suitable exposure time can be increased, which helps to record more biometric information at the edge of the image, facilitating the extraction of biometric information and improving the accuracy of biometric identification.

[0055] In some possible implementations, the light-transmitting element 100 may be Figure 8 Any lens in the optical lens shown, such as lens one L1, lens two L2, or lens three L3, can be used. Of course, the remaining lenses can also serve as first lenses. For example, when lens one L1 serves as the light-transmitting element, lens two L2 and lens three L3 serve as two first lenses. In this way, the light-transmitting element 100 can both modulate light and optimize relative illumination, thereby avoiding the need to add new components due to the light-transmitting element 100 and facilitating its application in small spaces.

[0056] In some possible implementations, the number of first lenses in the optical lens can be one, two, or more. As before, the order of the first lenses and light-transmitting elements in the reflected light path is not limited; the first lenses and light-transmitting elements can be arranged sequentially (e.g., ...). Figure 8 In this configuration, when lens 3 (L3) serves as the light-transmitting element, lens 1 (L1) and lens 2 (L2) serve as the two first lenses, or the light-transmitting element and the first lens are arranged sequentially (e.g., ...). Figure 8In this configuration, when lens L1 serves as the light-transmitting element, lenses L2 and L3 serve as two first lenses. Alternatively, the light-transmitting element can be positioned at any location between at least two first lenses (e.g., ...). Figure 8 In this configuration, when lens 2 L2 serves as the light-transmitting element, lens 1 L1 and lens 3 L3 serve as two first lenses.

[0057] In some possible implementations, an aperture stop is also provided in the optical lens. The aperture stop can be located between any two first lenses or between a first lens and a second lens in the optical lens, or at the top or bottom of a lens group consisting of at least two first lenses, or at the top or bottom of a lens group consisting of at least one first lens and a second lens. Considering the blocking effect of the aperture stop on light, the variation in the incident position of light at different field of view angles near the aperture stop is small, making it difficult to adjust the transmittance of different regions from the incident position. Therefore, when setting the light-transmitting element 100, it should be kept as far away from the aperture stop as possible. More specifically, the side surface of the light-transmitting element 100 with the adjustment film can be kept away from the aperture stop. In this way, the variation in the incident position of light at different field of view angles on the light-transmitting element 100 is relatively large, thereby facilitating the adjustment of the light transmittance of the aforementioned different regions through the adjustment film, and realizing targeted adjustment of the transmittance of light at different field of view angles at the light-transmitting element 100.

[0058] For example Figure 8 The optical lens includes three lenses (lens L1, lens L2 and lens L3), the aperture stop STO is set between lens L2 and lens L3, the light transmission element 100 can be lens L1 (as a second lens), and the adjustment film can be located on the side surface of lens L1 opposite to the aperture stop STO.

[0059] In some possible implementations, to facilitate the deposition of the aforementioned adjustment film, the area of ​​the optical surface on which it is located can be maximized, that is, the diameter of the lens of the light-transmitting element is larger than the diameter of any one of the first lenses, for example... Figure 8 As shown, the light-transmitting element 100 can be a lens L1 with the largest lens diameter.

[0060] Another aspect of the embodiments of this application, such as Figure 8 As shown, an optical fingerprint acquisition module 20 is provided, including an image sensor and any of the above-mentioned optical lenses. The optical lens is located on the receiving side of the image sensor. The reflected light from the fingerprint is first modulated by the lens and then incident on the photosensitive surface L5 of the image sensor for imaging.

[0061] In another aspect of the embodiments of this application, an electronic device is provided, such as... Figure 8As shown, it includes a display screen L0 and an optical fingerprint acquisition module 20 of any of the above types, with the optical fingerprint acquisition module 20 located below the display screen L0.

[0062] When the target object touches the upper surface of the display screen, part of the light reflected by the target object can pass through the display screen L0 and be incident on the optical fingerprint acquisition module 20 to form an image, thereby realizing the acquisition of the target object's biometric information.

[0063] It should be understood that the target object in this application may be the palm or other hand in addition to the fingers. Therefore, the biometric information of the target object includes, but is not limited to, fingerprint information, palm print information, finger vein information, etc.

[0064] The display L0 can be an Organic Light Emitting Diode (OLED) display or a Liquid Crystal Display (LCD), etc. A fingerprint recognition method can be preset in this electronic device. This method typically includes steps such as fingerprint image acquisition, preprocessing, feature extraction, and feature matching. Some or all of these steps can be implemented using traditional Computer Vision (CV) algorithms, or using deep learning algorithms based on Artificial Intelligence (AI). Fingerprint recognition technology can be applied to portable or mobile terminals such as smartphones, tablets, and gaming devices, as well as other electronic devices such as smart locks, cars, and bank ATMs for fingerprint unlocking, fingerprint payment, fingerprint attendance, and identity authentication.

[0065] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0066] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0067] It should also be noted that in the apparatus, equipment, and methods of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions of this application.

[0068] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0069] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. An optical lens, characterized in that, The optical lens includes a first lens and a light-transmitting element disposed in the reflected light path, wherein the reflected light path is formed from reflected light from the fingerprint; The light-transmitting element includes a light-transmitting substrate and a regulating film; The optical surface of at least one side of the light-transmitting substrate includes a central region and a peripheral region surrounding the outside of the central region; The adjustment film is provided in the central region and / or at least one of the peripheral regions to adjust the light transmittance of the light-transmitting element corresponding to the central region to be less than the light transmittance of the light-transmitting element corresponding to the peripheral region.

2. The optical lens as described in claim 1, characterized in that, One adjustment membrane is provided in each of the peripheral areas, and the number of adjustment membranes is equal to the number of peripheral areas. The adjustment membrane is an anti-reflection membrane. Alternatively, the regulating film may be provided in the central region, wherein there is one regulating film, and the regulating film is a light-shielding film.

3. The optical lens as described in claim 1, characterized in that, One regulating membrane is provided in the central region and in each of the peripheral regions; The regulating film located in the central area is an anti-reflection film, the regulating film located in the peripheral area is an anti-reflection film, and the light transmittance of the regulating film located in the central area is less than the light transmittance of the regulating film located in the peripheral area; or, the regulating film located in the central area is a light-blocking film, and the regulating film located in the peripheral area is an anti-reflection film.

4. The optical lens as described in claim 3, characterized in that, The regulating film located in the central area is a light-shielding film, and the regulating film located in the peripheral area is an anti-reflection film; The optical surface also includes a non-coated region located between the central region and the peripheral region, where the adjustment film is not disposed.

5. The optical lens as described in any one of claims 2 to 4, characterized in that, When the number of the peripheral regions is at least two and one adjustment film is provided in each of the peripheral regions, the light transmittance of the adjustment film gradually increases along the direction from the center to the edge of the light-transmitting substrate.

6. The optical lens as described in any one of claims 2 to 4, characterized in that, The antireflective coating comprises alternating and stacked high-refractive-index layers and low-refractive-index layers, and the light transmittance of the antireflective coating is positively correlated with the total number of high-refractive-index layers and low-refractive-index layers contained in the antireflective coating.

7. The optical lens according to any one of claims 1 to 4, characterized in that, The optical surface of at least one side of the light-transmitting substrate is planar; Alternatively, the optical surface of at least one side of the light-transmitting substrate may be convex or concave along the optical axis of the light-transmitting element.

8. The optical lens according to any one of claims 1 to 4, characterized in that, The orthographic projection of the central region along the optical axis of the light-transmitting element is circular, and the orthographic projection of the peripheral region along the optical axis of the light-transmitting element is annular.

9. The optical lens according to any one of claims 1 to 4, characterized in that, The optical lens also includes an aperture stop, and the adjustment film is disposed on the optical surface of the light-transmitting element on the side away from the aperture stop.

10. The optical lens according to any one of claims 1 to 4, characterized in that, The light-transmitting element is a second lens.

11. The optical lens according to any one of claims 1 to 4, characterized in that, The area of ​​the optical surface of the light-transmitting element is greater than the area of ​​the light-incident or light-exiting surface of any of the first lenses.

12. An optical fingerprint acquisition module, characterized in that, It includes an image sensor and the optical lens as described in any one of claims 1 to 11, wherein the optical lens is located on the receiving side of the image sensor, and reflected light from the fingerprint enters the image sensor after passing through the optical lens.

13. An electronic device, characterized in that, It includes a display screen and an optical fingerprint acquisition module as described in claim 12, wherein the optical fingerprint acquisition module is located below the display screen.

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