Lens system, fingerprint identification device and terminal equipment

Abstract

The application provides a lens system, a fingerprint identification device and a terminal device. The lens system comprises: a first lens and a second lens arranged in sequence from an object side to an image side; the first lens is a negative lens, the first lens has a concave surface facing the object side and a convex surface facing the image side, at least one surface of the first lens is aspherical; the second lens is a positive lens, the second lens has a convex surface facing the image side, at least one surface of the second lens is aspherical; the focal length f1 of the first lens and the focal length f2 of the second lens satisfy -5 < f1 / f2 < -2.61. Through the technical scheme, the surface type and the focal length distribution of the two lenses in the lens system are designed, so that the lens system has better imaging quality. Therefore, the lens system has lower cost, lower structural complexity and smaller size while having better imaging quality, which is conducive to the promotion and use of the lens system in the fingerprint imaging device or other imaging device.

Description

Technical Field

[0001] This application relates to the field of optical imaging, and more specifically, to lens systems, fingerprint recognition devices, and terminal devices. Background Technology

[0002] The emergence of optical under-display fingerprint recognition has enabled mobile phones to eliminate physical fingerprint buttons, increasing the freedom of mobile phone appearance design, increasing the screen-to-body ratio, and improving the aesthetic design. It has now become one of the best solutions for mobile phone fingerprint recognition.

[0003] With the booming development of the mobile phone industry, while optical under-display fingerprint technology is launching various new technologies to pursue higher performance, it is also very important to further simplify existing solutions and reduce costs.

[0004] Therefore, how to provide a low-cost and high-performance optical imaging system and fingerprint recognition device is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] This application provides a lens system, a fingerprint recognition device, and a terminal device, which have low cost and high imaging performance.

[0006] In a first aspect, a lens system is provided, comprising: a first lens and a second lens arranged sequentially from the object side to the image side; the first lens is a negative power lens, having a concave surface facing the object side and a convex surface facing the image side, and at least one surface of the first lens is aspherical; the second lens is a positive power lens, having a convex surface facing the image side, and at least one surface of the second lens is aspherical; the focal length f1 of the first lens and the focal length f2 of the second lens satisfy -5 <f1 / f2<-2.61。

[0007] The technical solution of this application provides a lens system including two lenses, which has lower cost, lower structural complexity, and smaller size. Furthermore, by designing the surface shape and optical power distribution of the two lenses in this lens system, superior image quality can be achieved. In summary, the lens system provided by this application combines superior image quality with lower cost, lower structural complexity, and smaller size, which is beneficial for its promotion and use in fingerprint imaging devices or other imaging devices.

[0008] In some possible implementations, the lens system is used to be positioned below the display screen of the electronic device, and the maximum image height Y' of the lens system on the imaging plane, the focal length f, and the distance TTL from the lower surface of the display screen to the imaging plane satisfy 0.35 < |Y' / (f*TTL)| < 0.58.

[0009] Through the technical solution of this embodiment, there is a high correlation among the maximum image height Y' of the lens system on the imaging surface, the focal length f of the lens system, and the distance TTL from the lower surface of the display screen to the imaging surface. It can not only affect the overall size of the lens system, but also affect the optical imaging performance of the lens system. By comprehensively considering the proportional relationship among these three, it is possible to ensure the overall optical imaging performance of the lens system provided by the embodiments of the present application while meeting the thickness space below the display screen.

[0010] In some possible embodiments, the focal length f of the lens system and the focal length f1 of the first lens satisfy -6 < f1 / f < -3; and / or, the focal length f of the lens system and the focal length f2 of the second lens satisfy 1.15 < f2 / f < 1.4.

[0011] Through the technical solution of this embodiment, the light power distribution of the lens system can be further optimized, enabling the lens system to obtain a more reasonable optical group structure, controlling the reasonable distribution of aberrations between the first lens and the second lens, and further improving the optical imaging quality of the lens system.

[0012] In some possible embodiments, the focal length f1 of the first lens and the radius of curvature r1 of the surface of the first lens facing the object side satisfy 4.1 < f1 / r1 < 8; and / or, the focal length f1 of the first lens and the radius of curvature r2 of the surface of the first lens facing the image side satisfy 1.8 < f1 / r2 < 5.2.

[0013] Through the technical solution of this embodiment, by designing the proportional relationship between the radii of curvature of the two surfaces of the first lens and the focal length of the first lens, the surface shape and optical performance of the first lens can be further optimized. Through the reasonable curvature distribution and surface shape design of the first lens, the aberrations generated by the large-angle incident light brought by the large FOV can be effectively corrected, reducing the imaging pressure on the subsequent optical elements and effectively improving the imaging quality.

[0014] In some possible embodiments, the focal length f2 of the second lens and the radius of curvature r3 of the surface of the second lens facing the object side satisfy 0.2 < f2 / r3 < 0.4; and / or, the focal length f2 of the second lens and the radius of curvature r4 of the surface of the second lens facing the image side satisfy -1.8 < f2 / r4 < -1.6.

[0015] Through the technical solution of this embodiment, by designing the proportional relationship between the radii of curvature of the two surfaces of the second lens and the focal length of the second lens, the surface shape and optical performance of the second lens can be further optimized. Through the reasonable curvature distribution and surface shape design of the second lens, while further correcting aberrations, the distortion generated by the lens system can be controlled.

[0016] In some possible embodiments, the radius of curvature r1 of the surface of the first lens facing the object side and the radius of curvature r2 of the surface of the first lens facing the image side satisfy 0.4 < r1 / r2 < 0.65; and / or, the radius of curvature r3 of the surface of the second lens facing the object side and the radius of curvature r4 of the surface of the second lens facing the image side satisfy -8.5 < r3 / r4 < -3.5.

[0017] Through the technical solution of this embodiment, by designing the proportional relationship of the radii of curvature of the two surfaces of the first lens and the second lens, the surface shapes and optical properties of the first lens and the second lens can be further optimized. A reasonable curvature design of the first lens and the second lens can reduce the sensitivity of the lens. That is, even if the first lens and the second lens have certain production and assembly tolerances during production and assembly, the optical imaging performance of the first lens and the second lens can be guaranteed. Through the technical solution of this embodiment, the production yield of the lens system can be improved.

[0018] In some possible embodiments, the thickness CT1 of the first lens on the optical axis and the thickness CT2 of the second lens on the optical axis satisfy 0.3 < CT1 / CT2 < 0.59.

[0019] Through the technical solution of this embodiment, the thicknesses of the first lens and the second lens on the optical axis can characterize the strengths of the first lens and the second lens. When the thickness is relatively thick, the strengths of the first lens and the second lens are greater. Therefore, the overall lens system can be more robust, effectively preventing external force damage and enhancing the service life of the lens system. In addition, by designing the ratio of the thicknesses of the first lens and the second lens on the optical axis, the optical properties of the two lenses can also be made to match each other, thereby enhancing the overall imaging performance of the lens system.

[0020] In some possible embodiments, the refractive index n1 of the first lens satisfies 1.5 < n1 < 1.6, and the dispersion coefficient v1 of the first lens satisfies 53 < v1 < 60; and / or, the refractive index n2 of the second lens satisfies 1.5 < n2 < 1.6, and the dispersion coefficient v2 of the second lens satisfies 53 < v2 < 60.

[0021] Through the technical solution of this embodiment, the first lens and the second lens can be lenses with a low refractive index and a low dispersion coefficient. The refractive index and the dispersion coefficient are also important for the imaging quality of the lens. Using the first lens and the second lens with a lower refractive index and smaller dispersion to design the lens system can effectively reduce the dispersion of the lens system and provide an appropriate balance of aberration.

[0022] In some possible embodiments, the lens system further includes: an aperture disposed between the first lens and the second lens.

[0023] Through the technical solution of this embodiment, the aperture can be used to adjust the size of the light signal or the imaging range. By setting the aperture to adjust the light signal or the imaging range, the light signal carrying fingerprint information can be imaged on the surface of the fingerprint image sensor to the greatest extent, so that the fingerprint image sensor can obtain more fingerprint information and further improve the resolution of fingerprint recognition.

[0024] In some possible implementations, the lens system further includes an infrared light filter disposed on the image-facing side of the second lens.

[0025] The technical solution of this embodiment uses an IR filter to prevent infrared light from interfering with imaging. For example, when the lens system is used in a fingerprint recognition device, the IR filter can prevent fingerprint recognition failure caused by strong ambient light when the user is outdoors.

[0026] In some possible implementations, the lens system further includes a filter bonding adhesive for bonding an infrared filter to the imaging surface of the lens system.

[0027] The technical solution of this embodiment makes it easy to install IR filters in the lens system, thereby reducing the installation cost of IR filters in the lens system and improving the production efficiency and manufacturing yield of the lens system.

[0028] In some possible implementations, the system parameters of the lens system satisfy at least one of the following: field of view (FOV) greater than 110°; F-number less than 1.8; or distortion less than 5%.

[0029] Through this implementation, when the FOV of the lens system is greater than 110°, this large FOV ensures that the lens system can maintain a sufficiently large object-side field of view while keeping the optical length small, allowing the imaging surface to acquire enough object-side information. For example, when the lens system is applied to a fingerprint recognition device, the device can acquire enough fingerprint information for recognition, ensuring the accuracy of fingerprint recognition. When the F-number of the lens system is less than 1.8, this small F-number allows for a shorter exposure time. When the lens system is applied to an under-display fingerprint recognition device, it can adapt to the low transmittance environment of the screen, improving the detection capability of weak fingerprint signals. When the distortion of the lens system is controlled within 5%, and the lens system is applied to an under-display fingerprint recognition device, it can reduce fingerprint ridge deformation caused by distortion and reduce the influence of moiré patterns caused by the screen structure.

[0030] In a second aspect, a fingerprint recognition device is provided, comprising: a fingerprint image sensor, and a lens system as described in the first aspect or any possible embodiment of the first aspect; wherein the fingerprint image sensor is disposed below the lens system and is used to receive fingerprint light signals transmitted through the lens system and process the fingerprint light signals to obtain a fingerprint image.

[0031] In some possible implementations, the fingerprint recognition device further includes a bracket; wherein the lens system is interference-fitted into the bracket.

[0032] In some possible implementations, the fingerprint recognition device further includes a circuit board; wherein the circuit board is disposed below the fingerprint image sensor and electrically connected to the fingerprint image sensor, and the circuit board is used to realize the transmission of electrical signals between the fingerprint recognition device and the outside.

[0033] Thirdly, a terminal device is provided, comprising: a display screen, and a fingerprint recognition device according to the second aspect or any possible embodiment of the second aspect; wherein the fingerprint recognition device is disposed below the display screen to realize under-display fingerprint recognition. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of an electronic device to which the embodiments of this application may be applied.

[0035] Figure 2 A schematic structural diagram of a lens system is provided for an embodiment of this application.

[0036] Figure 3 Another schematic structural diagram of the lens system is provided for embodiments of this application.

[0037] Figure 4 yes Figure 3 The diagram shows the astigmatism and distortion curves of the lens system with the layout shown.

[0038] Figure 5 yes Figure 3 The MTF diagram of the lens system with the layout shown.

[0039] Figure 6 Another schematic structural diagram of the lens system is provided for embodiments of this application.

[0040] Figure 7 yes Figure 6 The diagram shows the astigmatism and distortion curves of the lens system with the layout shown.

[0041] Figure 8 yes Figure 6 The MTF diagram of the lens system with the layout shown.

[0042] Figure 9Another schematic structural diagram of the lens system is provided for embodiments of this application.

[0043] Figure 10 yes Figure 9 The diagram shows the astigmatism and distortion curves of the lens system with the layout shown.

[0044] Figure 11 yes Figure 9 The MTF diagram of the lens system with the layout shown.

[0045] Figure 12 Another schematic structural diagram of the lens system is provided for embodiments of this application.

[0046] Figure 13 yes Figure 12 The diagram shows the astigmatism and distortion curves of the lens system with the layout shown.

[0047] Figure 14 yes Figure 12 The MTF diagram of the lens system with the layout shown.

[0048] Figure 15 Another schematic structural diagram of the lens system is provided for embodiments of this application.

[0049] Figure 16 yes Figure 15 The diagram shows the astigmatism and distortion curves of the lens system with the layout shown.

[0050] Figure 17 yes Figure 15 The MTF diagram of the lens system with the layout shown.

[0051] Figure 18 This is a schematic block diagram of a fingerprint recognition device provided in an embodiment of this application.

[0052] Figure 19 This is a schematic structural diagram of a fingerprint recognition device provided in an embodiment of this application.

[0053] Figure 20 This is a schematic block diagram of a terminal device provided in an embodiment of this application. Detailed Implementation

[0054] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0055] It should be understood that the embodiments of this application can be applied to optical fingerprint systems, including but not limited to optical fingerprint recognition systems and products based on optical fingerprint imaging. The embodiments of this application are only illustrated using optical fingerprint systems as an example, but should not be construed as limiting the embodiments of this application in any way. The embodiments of this application are also applicable to other systems that use optical imaging technology.

[0056] As a common application scenario, the optical fingerprint system provided in this application embodiment can be applied to smartphones, tablets, and other mobile terminals or other electronic devices with displays. More specifically, in the above-mentioned electronic devices, the fingerprint recognition device can be specifically an optical fingerprint device, which can be set in a partial area or the entire area under the display screen, thereby forming an under-display optical fingerprint system.

[0057] like Figure 1 The diagram shows a structural schematic of an electronic device to which this application embodiment can be applied. The electronic device 10 includes a display screen 120 and an optical fingerprint device 130, wherein the optical fingerprint device 130 is disposed in a partial area below the display screen 120. The optical fingerprint device 130 includes a fingerprint image sensor, which includes a sensing array 133 having multiple optical sensing units 131. The area where the sensing array 133 is located, or its sensing area, is the fingerprint detection area 103 of the optical fingerprint device 130. Figure 1 As shown, the fingerprint detection area 103 is located within the display area of ​​the display screen 120. In an alternative embodiment, the optical fingerprint device 130 may also be located in other locations, such as the side of the display screen 120 or the non-transparent area of ​​the edge of the electronic device 10, and the light signal of at least a portion of the display area of ​​the display screen 120 may be guided to the optical fingerprint device 130 through an optical path design, so that the fingerprint detection area 103 is actually located within the display area of ​​the display screen 120.

[0058] It should be understood that the area of ​​the fingerprint detection area 103 may be different from the area of ​​the sensing array of the optical fingerprint device 130. For example, through optical path design such as lens imaging, reflective folding optical path design or other optical path design such as light convergence or reflection, the area of ​​the fingerprint detection area 103 of the optical fingerprint device 130 may be larger than the area of ​​the sensing array of the optical fingerprint device 130.

[0059] As an optional implementation method, such as Figure 1 As shown, the optical fingerprint device 130 includes a light detection section 134 and an optical component 132. The light detection section 134 includes a sensor array 133 and a reading circuit and other auxiliary circuits electrically connected to the sensor array 133. It can be fabricated on a single chip (die) using semiconductor technology, such as an optical imaging chip or a fingerprint image sensor. The optical component 132 can be disposed above the sensor array of the light detection section 134. It can specifically include a light guide layer or a light path guiding structure and other optical elements. The light guide layer or light path guiding structure is mainly used to guide reflected light from the finger surface to the sensor array for optical detection.

[0060] The light guide layer or optical path guiding structure of the optical component 132 can be implemented in various ways. For example, in some embodiments, the light guide layer or optical path guiding structure can be an optical lens layer, which has one or more lenses for converging the reflected light from the finger onto the sensing array of the light detection portion 134 below it, so that the sensing array can form an image based on the reflected light to obtain a fingerprint image of the finger. Optionally, the optical lens layer can also form a pinhole in the optical path of the lens unit. The pinhole can cooperate with the optical lens layer to expand the field of view of the optical fingerprint device, thereby improving the fingerprint imaging effect of the optical fingerprint device 130.

[0061] As an optional embodiment, the display screen 120 can be a display screen with self-emissive display units, such as an Organic Light-Emitting Diode (OLED) display screen or a Micro-LED display screen. Taking an OLED display screen as an example, the optical fingerprint device 130 can use the display unit (i.e., OLED light source) of the OLED display screen 120 located in the fingerprint detection area 103 as the excitation light source for optical fingerprint detection. When the finger 140 is pressed on the fingerprint detection area 103, the display screen 120 emits a beam of light 111 towards the target finger 140 above the fingerprint detection area 103. This light 111 is reflected on the surface of the finger 140 to form reflected light or scattered through the inside of the finger 140 to form scattered light. In the relevant patent applications, for ease of description, the above-mentioned reflected light and scattered light are collectively referred to as reflected light. Because the ridges and valleys of a fingerprint have different light-reflecting abilities, the reflected light 151 from the fingerprint ridge and the reflected light 152 from the fingerprint valley have different light intensities. After passing through the optical component 132, the reflected light is received by the optical detection part 134 in the optical fingerprint device 130 and converted into a corresponding electrical signal, namely a fingerprint detection signal. Based on the fingerprint detection signal, fingerprint image data can be obtained, and fingerprint matching verification can be further performed, thereby realizing the optical fingerprint recognition function in the electronic device 10.

[0062] In other embodiments, the optical fingerprint device 130 may also employ a built-in light source or an external light source to provide the light signal for fingerprint detection. In this case, the optical fingerprint device 130 can be applied to a non-self-emissive display, such as a liquid crystal display or other passively illuminated display.

[0063] It should be understood that, in a specific implementation, the electronic device 10 also includes a transparent protective cover, which can be a glass cover or a sapphire cover, located above the display screen 120 and covering the front of the electronic device 10. This is because, in this embodiment, the so-called finger pressing on the display screen 120 actually refers to pressing on the cover above the display screen 120 or the surface of the protective layer covering the cover.

[0064] It should also be understood that, such as Figure 1 As shown, the electronic device 10 may further include a circuit board 150 disposed below the optical fingerprint device 130. The optical fingerprint device 130 can achieve electrical interconnection and signal transmission with other peripheral circuits or other components of the electronic device 10 through the circuit board 150. For example, the optical fingerprint device 130 can receive control signals from the processing unit of the electronic device 10 through the circuit board 150, and can also output fingerprint detection signals from the optical fingerprint device 130 to the processing unit or control unit of the electronic device 10 through the circuit board 150.

[0065] In the above-described embodiments, the optical component 132 may include a lens system formed by one or more lenses to transmit the fingerprint light signal formed after reflection or scattering by the finger. The design of this lens system affects the final fingerprint imaging quality and thus the fingerprint recognition effect; therefore, the design of this lens system is particularly important in the entire optical fingerprint system.

[0066] In some related technologies, to ensure image quality, the lens system includes three or more lenses. This lens system has a complex structure, is relatively thick, and has a high cost. The large thickness is not conducive to the installation of this lens system in thinner and lighter electronic devices, and the high cost is not conducive to the promotion and use of this lens system in low-cost electronic devices.

[0067] In view of this, this application provides a lens system that includes only two lenses. By designing these two lenses, the lens system can have both low cost and good imaging performance.

[0068] Figure 2 A schematic structural diagram of a lens system 200 provided in an embodiment of this application is shown.

[0069] like Figure 2 As shown, the lens system 200 includes a first lens 210 and a second lens 220 arranged sequentially from the object side to the image side.

[0070] Specifically, the first lens 210 is a negative power lens, having a concave surface facing the object side and a convex surface facing the image side, and at least one surface of the first lens 210 is aspherical. The second lens 220 is a positive power lens, having a convex surface facing the image side, and at least one surface of the second lens 220 is aspherical. The focal length f1 of the first lens 210 and the focal length f2 of the second lens 220 satisfy -5 <f1 / f2<-2.61。

[0071] In this embodiment, the first lens 210 of the lens system 200 facing the object side has negative optical power, which enables the lens system 200 to obtain a larger object-side field of view. Additionally, the second lens 220 of the lens system 200 facing the image side has positive optical power, which can converge light signals and shorten the overall length of the lens system 200.

[0072] The first lens 210 has a concave surface facing the object side and a convex surface facing the image side. Both the concave and convex surfaces are located in the paraxial region of the first lens 210. During the imaging process of the lens system 200, the imaging quality of the paraxial region of the first lens 210 has a significant impact on the final imaging effect of the lens system 200. Therefore, in this embodiment, the surface of the paraxial region of the first lens 210 is designed to ensure the imaging performance of the first lens 210 throughout the entire lens system 200.

[0073] The second lens 220 has a convex surface facing the image. Optionally, the entire image-facing surface of the second lens 220 can be convex, or the image-facing surface of the second lens 220 located in the paraxial region is convex. During the imaging process of the second lens 220, the design of the image-facing surface of the second lens 220 has a significant impact on the imaging of the entire lens system 200. Therefore, in this embodiment, the image-facing surface of the second lens 220 is designed to ensure the imaging performance of the second lens 220 in the entire lens system 200.

[0074] It should be noted that the object-facing surface of the second lens 220 can be convex, concave, or flat; this application embodiment does not specifically limit it. In some specific implementations, both the object-facing and image-facing surfaces of the second lens 220 are convex, in which case the second lens 220 can be a biconvex mirror.

[0075] Furthermore, at least one surface of the first lens 210 and the second lens 220 can be aspherical. Compared to a spherical design, designing at least one surface of the first lens 210 and the second lens 220 as aspherical allows for more flexible surface design of the first lens 210 and the second lens 220, increases the design freedom of the lens system 200, and is beneficial for further optimizing and improving the overall performance of the lens system 200.

[0076] In addition to the surface design of the first lens 210 and the second lens 220 described above, in this embodiment, the focal length f1 of the first lens 210 and the focal length f2 of the second lens 220 satisfy -5 <f1 / f2<-2.61。

[0077] Specifically, the focal length of a lens can characterize its optical performance to a certain extent. By designing the focal length of the first lens 210 and the second lens 220 in the above proportion, the lens system 200 can have a more reasonable distribution of optical power, control the aberrations to be reasonably distributed between the lenses, and thus enable the lens system 200 to obtain relatively good imaging quality with only two lenses.

[0078] In summary, the technical solutions of this application provide a lens system 200 including two lenses. By designing the surface shape and power distribution of the two lenses in the lens system 200, the lens system 200 can achieve superior imaging quality. Therefore, the lens system 200 provided by this application not only has superior imaging quality but also lower cost, lower structural complexity, and smaller size, which is beneficial for its promotion and use in fingerprint imaging devices or other imaging devices.

[0079] Optionally, through the aforementioned design of the lens system 200, the system parameters of the lens system can meet at least one of the following: field of view (FOV) greater than 110°; F number less than 1.8; or distortion less than 5%, so as to achieve better imaging quality of the lens system 200.

[0080] Specifically, the field of view (FOV) is used to characterize the field of view of a lens. When the lens size is the same, the larger the FOV, the more information the lens can obtain. In other words, a lens with a large FOV can obtain more information.

[0081] The F-number, also written as Fno., is a parameter that indicates the light-gathering ability of a lens. The smaller the F-number, the more light enters the lens per unit time, and the shorter the exposure time can be.

[0082] Lens distortion is used to measure the degree of visual distortion in an image. Understandably, the smaller the lens distortion, the better the image quality.

[0083] When the field of view (FOV) of the lens system 200 is greater than 110°, this large FOV ensures that the lens system 200 can have a sufficiently large object-side field of view while maintaining a small optical length, allowing the imaging surface to acquire enough object-side information. For example, when the lens system 200 is applied to a fingerprint recognition device, the fingerprint recognition device can acquire enough fingerprint information for recognition, ensuring the accuracy of fingerprint recognition.

[0084] When the aperture number of the lens system 200 is less than 1.8, this small aperture number allows for a shorter exposure time. When the lens system 200 is applied to an under-display fingerprint recognition device, it can adapt to the low transmittance environment of the screen and improve the detection capability of weak fingerprint signals.

[0085] With the distortion of the lens system 200 controlled within 5%, and the lens system 200 applied to the under-display fingerprint recognition device, the distortion of fingerprint patterns caused by distortion can be reduced on the one hand, and the influence of moiré patterns caused by the screen structure can be reduced on the other hand.

[0086] In summary, through the technical solutions of the embodiments of this application, the lens system 200 can be made to have a larger FOV, a smaller F number and a smaller distortion by designing the first lens 210 and the second lens 220 in the lens system 200, thereby effectively improving the overall imaging performance of the lens system 200.

[0087] Optionally, in some embodiments, the lens system 200 is used to be disposed below the display screen of the electronic device, and the maximum image height Y', focal length f, and distance TTL from the lower surface of the display screen to the imaging surface of the lens system 200 satisfy 0.35 < |Y' / (f*TTL)| < 0.58.

[0088] Specifically, the maximum image height Y' of the lens system 200 on the imaging plane is the radius of the maximum imaging circle of the lens system 200 on the imaging plane. When the lens system 200 is applied to a fingerprint recognition device, a fingerprint image sensor can be disposed on the imaging plane of the lens system 200, and the fingerprint image sensor may include the features described above. Figure 1 The light detection section 134 in the illustrated embodiment is used to detect the fingerprint light signal transmitted through the lens system 200.

[0089] When the lens system 200 is positioned below the display screen of an electronic device, the distance TTL between the lower surface of the display screen and the imaging surface of the lens system 200 can be used to characterize the thickness space of the lens system 200 positioned below the display screen.

[0090] There is a high correlation among the maximum image height Y' of the lens system 200 on the imaging surface, the focal length f of the lens system 200, and the distance TTL from the lower surface of the display screen to the imaging surface. It can not only affect the overall size of the lens system 200, but also affect the optical imaging performance of the lens system 200. Considering the proportional relationship among the three comprehensively, it can make the lens system 200 provided by the embodiments of the present application ensure the overall optical imaging performance of the lens system 200 on the basis of meeting the thickness space below the display screen.

[0091] Optionally, in some embodiments, the focal length f of the lens system 200 and the focal length f1 of the first lens 210 satisfy -6 < f1 / f < -3; and / or, the focal length f of the lens system 200 and the focal length f2 of the second lens 220 satisfy 1.15 < f2 / f < 1.4.

[0092] Specifically, in this embodiment, in addition to satisfying -5 < f1 / f2 < -2.61, the optical power distribution of the first lens 210 and the second lens 220 in the lens system 200 further satisfies -6 < f1 / f < -3 and / or 1.15 < f2 / f < 1.4. Through the technical solution of this embodiment, the optical power distribution of the lens system 200 can be further optimized, so that the lens system 200 obtains a more reasonable optical group structure, controls the reasonable distribution of aberrations between the first lens 210 and the second lens 220, and further improves the optical imaging quality of the lens system 200.

[0093] Optionally, in some embodiments, the focal length f1 of the first lens 210 and the radius of curvature r1 of the surface of the first lens 210 facing the object side satisfy 4.1 < f1 / r1 < 8; and / or, the focal length f1 of the first lens 210 and the radius of curvature r2 of the surface of the first lens 210 facing the image side satisfy 1.8 < f1 / r2 < 5.2.

[0094] Through the technical solution of this embodiment, by designing the proportional relationship between the radii of curvature of the two surfaces of the first lens 210 and the focal length of the first lens 210, the surface shape and optical performance of the first lens 210 can be further optimized. Through the reasonable curvature distribution and surface shape design of the first lens 210, the aberrations generated by the large-angle incident light brought by the large FOV can be effectively corrected, the imaging pressure of the subsequent optical elements can be reduced, and the imaging quality can be effectively improved.

[0095] Optionally, in some embodiments, the focal length f2 of the second lens 220 and the radius of curvature r3 of the surface of the second lens 220 facing the object side satisfy 0.2 < f2 / r3 < 0.4; and / or, the focal length f2 of the second lens 220 and the radius of curvature r, of the surface of the second lens 220 facing the image side satisfy -1.8 < f2 / r4 < -1.6.

[0096] Through the technical solution of this embodiment, by designing the ratio relationship between the radii of curvature of the two surfaces of the second lens 220 and the focal length of the second lens 220, the surface shape and optical performance of the second lens 220 can be further optimized. Through the reasonable curvature distribution and surface shape design of the second lens 220, while being able to further correct aberrations, the distortion generated by the lens system 200 can be controlled.

[0097] Optionally, in some embodiments, the radius of curvature r1 of the surface of the first lens 210 facing the object side and the radius of curvature r2 of the surface of the first lens 210 facing the image side satisfy 0.4 < r1 / r2 < 0.65; and / or, the radius of curvature r3 of the surface of the second lens 220 facing the object side and the radius of curvature r4 of the surface of the second lens 220 facing the image side satisfy -8.5 < r3 / r4 < -3.5.

[0098] Through the technical solution of this embodiment, by designing the ratio relationship between the radii of curvature of the two surfaces of the first lens 210 and the second lens 220, the surface shapes and optical performance of the first lens 210 and the second lens 220 can be further optimized. The reasonable curvature design of the first lens 210 and the second lens 220 can reduce the sensitivity of the lenses, that is, even if the first lens 210 and the second lens 220 have certain production and assembly tolerances during production and assembly, the optical imaging performance of the first lens 210 and the second lens 220 can be guaranteed. Through the technical solution of this embodiment, the production yield of the lens system 200 can be improved.

[0099] Optionally, in some embodiments, the thickness CT1 of the first lens 210 on the optical axis and the thickness CT2 of the second lens 220 on the optical axis satisfy 0.3 < CT1 / CT2 < 0.59.

[0100] Through the technical solution of this embodiment, the thicknesses of the first lens 210 and the second lens 220 on the optical axis can characterize the strengths of the first lens 210 and the second lens 220. When the thickness is relatively thick, the strengths of the first lens 210 and the second lens 220 are relatively large. Therefore, the overall lens system 200 can be more robust, effectively preventing external force damage and extending the service life of the lens system 200. In addition, by designing the ratio of the thicknesses of the first lens 210 and the second lens 220 on the optical axis, the optical performances of the two lenses can also be mutually adapted, thereby improving the overall imaging performance of the lens system 200.

[0101] Optionally, in some embodiments, the refractive index n1 of the first lens 210 satisfies 1.5 < n1 < 1.6, and the dispersion coefficient v1 of the first lens 210 satisfies 53 < v1 < 60; and / or, the refractive index n2 of the second lens 220 satisfies 1.5 < n2 < 1.6, and the dispersion coefficient v2 of the second lens 220 satisfies 53 < v2 < 60.

[0102] Through the technical solution of this embodiment, the first lens 210 and the second lens 220 can be lenses with low refractive index and low dispersion coefficient. Refractive index and dispersion coefficient are also important for the imaging quality of the lens. By designing the lens system 200 with a first lens 210 and a second lens 220 that have lower refractive index and smaller dispersion, the dispersion of the lens system 200 can be effectively reduced, providing a suitable aberration balance.

[0103] Optionally, to effectively reduce the manufacturing cost of the first lens 210 and the second lens 220, the materials of the first lens 210 and the second lens 220 can be resin, and the first lens 210 and the second lens 220 can be formed by injection molding of resin material. Therefore, through the technical solution of this embodiment, a low-cost, low-refractive-index, and low-dispersion-coefficient resin material can be provided to manufacture the first lens 210 and the second lens 220, thereby reducing the manufacturing cost of the lens system 200 while ensuring the optical imaging performance of the lens system 200.

[0104] Figure 3 Another schematic structural diagram of the lens system 200 provided in this application embodiment is shown. Optionally, the lens system 200 may be disposed below the display screen 20 of an electronic device. The display screen 20 may be... Figure 1 The display screen 120 shown, for example, the display screen 20 can be an OLED display or other type of display screen. For ease of light path illustration, the left side of the display screen 20 is the side facing the outside of the electronic device, and the right side of the display screen 20 is the side facing the inside of the electronic device.

[0105] like Figure 3 As shown, in this lens system 200, from the object side to the image side, the following components are arranged in sequence: a first lens 210, an aperture stop (not shown in the figure), and a second lens 220. The object side is the side of the lens system 200 facing the display screen 20, and the image side is the side of the lens system 200 facing away from the display screen 20. A fingerprint image sensor may be disposed on one side of the image side.

[0106] Specifically, in this embodiment, an aperture stop is disposed between the first lens 210 and the second lens 220. This aperture stop can be used to adjust the size of the light signal or the imaging range. By adjusting the light signal or imaging range using the aperture stop, the light signal carrying fingerprint information can be imaged onto the surface of the fingerprint image sensor to the greatest extent possible, enabling the fingerprint image sensor to obtain more fingerprint information and further improving the resolution of fingerprint recognition.

[0107] See also Figure 3As shown, in some embodiments, the lens system 200 may further include an infrared (IR) filter 230 disposed on the image-facing side of the second lens 220.

[0108] Specifically, the IR filter 230 is used to prevent infrared light in the external ambient light from interfering with imaging. For example, when the lens system 200 is used in a fingerprint recognition device, the IR filter 230 can prevent the problem of fingerprint recognition failure caused by strong ambient light when the user is outdoors.

[0109] In some embodiments, the lens system 200 may further include: a filter bonding adhesive for bonding the IR filter 230 to the imaging surface of the lens system 200.

[0110] Specifically, if the imaging surface of the lens system 200 is provided with an image sensor, such as a fingerprint image sensor, then the filter adhesive can be used to attach the IR filter 230 to the surface of the fingerprint image sensor.

[0111] With the technical solution of this embodiment, the installation method of IR filter 230 in lens system 200 is easy to realize, thus reducing the installation cost of IR filter 230 in lens system 200 and improving the production efficiency and manufacturing yield of lens system 200.

[0112] To illustrate the lens system 200 provided in this application in more detail, the design parameters of the lens system 200 in several specific embodiments are given below.

[0113] In the following embodiments, the upper and lower surfaces of the display screen 20 are designated as S1 and S2 respectively, in the order from object to image, the two surfaces of the first lens 210 are designated as S3 and S4 respectively, the surface of the aperture is designated as S5, the two surfaces of the second lens 220 are designated as S6 and S7 respectively, the surfaces of the IR filter 230 are designated as S8 and S9 respectively, and the surfaces of the filter adhesive are designated as S9 and S10, wherein S10 is also the imaging surface.

[0114] Optionally, the focal length, radius of curvature, thickness, refractive index, and dispersion coefficient of the first lens 210 and the second lens 220 in the lens system 200 can be designed according to the embodiments described above, so that the lens system 200 has good optical imaging performance. For example, the lens system 200 can meet at least one of the following: field of view (FOV) greater than 110°; F-number less than 1.8; or distortion less than 5%.

[0115] Alternatively, the lens system 200 can be designed to have good optical imaging performance by taking at least one of the following: radius of curvature, thickness, material, and conic coefficient of each surface (i.e., S1 to S10 above), and / or the aspherical higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A20, etc. of the aspherical lens in the lens system 200.

[0116] Example 1

[0117] The shapes of the components in the lens system 200 of this embodiment 1 can be seen in [reference]. Figure 3 As shown. In this embodiment 1, the focal length, radius of curvature, thickness, refractive index, and dispersion coefficient of the first lens 210 and the second lens 220 in the lens system 200 can be designed using the corresponding proportions in Table 1 below. The radius of curvature, thickness, material, and conic coefficient of each surface S1 to S10 in the lens system 200 can be the corresponding parameters in Table 2 below, and the aspherical higher-order coefficients of the aspherical surfaces in S1 to S10 can be the parameters shown in Table 3 below.

[0118] Table 1

[0119] project parameter <![CDATA[f1 / f2]]> -4.495 <![CDATA[f1 / f]]> -5.738 <![CDATA[f2 / f]]> 1.276 <![CDATA[f1 / r1]]> 7.859 <![CDATA[f1 / r2]]> 4.770 <![CDATA[f2 / r3]]> 0.340 <![CDATA[f2 / r4]]> -1.706 |Y' / (f*TTL)| 0.523 <![CDATA[CT1 / CT2]]> 0.398 <![CDATA[r1 / r2]]> 0.607 <![CDATA[r3 / r4]]> -5.019

[0120] Table 2

[0121]

[0122]

[0123] Table 3

[0124] surface A4 A6 A8 A10 A12 S3 2.74E+02 -9.57E+03 1.84E+05 -3.29E+05 -4.25E+07 S4 1.53E+01 1.08E+02 -1.11E+04 2.40E+05 -2.33E+06 S6 -1.33E+01 1.09E+03 -3.65E+04 -2.45E+04 1.71E+07 S7 -3.63E+03 7.40E+06 -4.89E+09 1.99E+12 -4.59E+14 surface A14 A16 A18 A20 S3 4.92E+08 1.02E+09 -2.46E+10 -3.44E+09 S4 7.84E+06 3.54E+07 -3.38E+08 6.90E+08 S6 3.89E+07 -1.76E+09 -2.07E+11 3.07E+12 S7 5.37E+16 2.08E+17 -8.50E+20 7.22E+22

[0125] It should be understood that blank positions corresponding to parameters in Tables 1 to 3 of this application embodiment indicate that the parameter is not present. In Table 1, "BK7" represents the model of optical glass, and "APL5014CL" represents the material of transparent resin. In Table 3, "E+02" represents "10 to the power of 2", and similarly, other values ​​can be deduced accordingly.

[0126] Based on the parameters shown in Tables 1 to 3, the parameters of the lens system 200 provided in this embodiment 1 are as follows: TTL = 3.588mm (distance from S2 to S10), f = 0.483mm, f1 = -2.771mm, f2 = 0.6163mm, Fno = 1.65, FOV = 128°.

[0127] Figures 4 to 5The images shown are, in order, the astigmatism and distortion curves and the magnitude (MTF) graph of the optical transfer function of the lens system 200 provided in Embodiment 1. Figure 4 Figure (a) in the figure is an astigmatism curve. Figure 4 Figure (b) in the figure is a distortion curve.

[0128] from Figures 4 to 5 The simulation diagram shows that the maximum object height Y of the lens system 200 is 5.3mm. Therefore, the object-side field of view is relatively large, and the maximum distortion is approximately -3%. The lens system 200 exhibits good performance with a large object-side FOV, low distortion, and low dispersion and chromatic aberration.

[0129] Example 2

[0130] The shape of each component in the lens system 200 of this embodiment 2 can be seen in [reference]. Figure 6 As shown. In this embodiment 2, the focal length, radius of curvature, thickness, refractive index, and dispersion coefficient of the first lens 210 and the second lens 220 in the lens system 200 can be designed using the corresponding proportions in Table 4 below. The radius of curvature, thickness, material, and conic coefficient of each surface S1 to S10 in the lens system 200 can be the parameters shown in Table 5 below, and the aspherical higher-order coefficients of the aspherical surfaces in S1 to S10 can be the parameters shown in Table 6 below.

[0131] Table 4

[0132] project parameter <![CDATA[f1 / f2]]> -3.710 <![CDATA[f1 / f]]> -4.779 <![CDATA[f2 / f]]> 1.288 <![CDATA[f1 / r1]]> 5.307 <![CDATA[f1 / r2]]> 2.792 <![CDATA[f2 / r3]]> 0.373 <![CDATA[f2 / r4]]> -1.669 |Y' / (f*TTL)| 0.446 <![CDATA[CT1 / CT2]]> 0.497 <![CDATA[r1 / r2]]> 0.526 <![CDATA[r3 / r4]]> -4.478

[0133] Table 5

[0134]

[0135]

[0136] Table 6

[0137]

[0138] Based on the parameters shown in Tables 4 to 6, the parameters of the lens system 200 provided in this embodiment 2 are as follows: TTL = 3.647mm (distance from S2 to S10), f = 0.457mm, f1 = -2.184mm, f2 = 0.589mm, Fno = 1.5, FOV = 119°.

[0139] Figures 7 to 8 The images shown are, in order, the astigmatism and distortion curves and the magnitude (MTF) graph of the optical transfer function of the lens system 200 provided in Embodiment 2. Figure 7Figure (a) in the figure is an astigmatism curve. Figure 6 Figure (b) in the figure is a distortion curve.

[0140] from Figures 7 to 8 The simulation diagram shows that the maximum object height Y of the lens system 200 is 4.74 mm, and the maximum distortion is approximately -2%. Furthermore, the lens system 200 has a relatively small F-number (Fno), i.e., 1.5, therefore, it can have a shorter exposure time.

[0141] Example 3

[0142] The shapes of the components in the lens system 200 of this embodiment 3 can be seen in [reference]. Figure 9 As shown. In this embodiment 3, the focal length, radius of curvature, thickness, refractive index, and dispersion coefficient of the first lens 210 and the second lens 220 in the lens system 200 can be designed using the corresponding proportions in Table 7 below. The radius of curvature, thickness, material, and conic coefficient of each surface S1 to S10 in the lens system 200 can be the parameters shown in Table 8 below, and the aspherical higher-order coefficients of the aspherical surfaces in S1 to S10 can be the parameters shown in Table 9 below.

[0143] Table 7

[0144] project parameter <![CDATA[f1 / f2]]> -3.509 <![CDATA[f1 / f]]> -4.591 <![CDATA[f2 / f]]> 1.308 <![CDATA[f1 / r1]]> 4.701 <![CDATA[f1 / r2]]> 2.295 <![CDATA[f2 / r3]]> 0.380 <![CDATA[f2 / r4]]> -1.663 |Y' / (f*TTL)| 0.432 <![CDATA[CT1 / CT2]]> 0.547 <![CDATA[r1 / r2]]> 0.488 <![CDATA[r3 / r4]]> -4.377

[0145] Table 8

[0146]

[0147]

[0148] Table 9

[0149] surface A4 A6 A8 A10 A12 S3 2.54E+00 -9.70E+00 2.32E+01 -1.85E+01 -3.45E+01 S4 6.44E+00 2.01E+02 -8.15E+03 1.40E+05 -1.24E+06 S6 -1.59E+01 8.01E+02 -3.46E+04 4.92E+05 6.90E+06 S7 -4.14E+00 2.36E+02 -6.19E+03 1.12E+05 -1.35E+06 surface A14 A16 A18 A20 S3 7.64E+01 7.86E-01 -1.01E+02 6.59E+01 S4 4.38E+06 1.28E+07 -1.56E+08 3.72E+08 S6 -1.42E+08 -4.23E+09 1.10E+11 -6.68E+11 S7 8.04E+06 1.40E+07 -4.57E+08 1.69E+09

[0150] Based on the parameters shown in Tables 7 to 9, the parameters of the lens system 200 provided in this embodiment 3 are as follows: TTL = 3.655mm (distance from S2 to S10), f = 0.426mm, f1 = -1.956mm, f2 = 0.557mm, Fno = 1.5, FOV = 118.7°.

[0151] Figures 10 to 11 The images shown are, in order, the astigmatism and distortion curves and the magnitude (MTF) graph of the optical transfer function of the lens system 200 provided in Embodiment 3. Figure 10 Figure (a) in the figure is an astigmatism curve. Figure 8 Figure (b) in the figure is a distortion curve.

[0152] from Figures 10 to 11The simulation diagram shows that the maximum object height Y of the lens system 200 is 4.74 mm, and the maximum distortion is approximately -2%. Furthermore, the lens system 200 can also have a relatively small F-number (Fno), i.e., 1.5, and therefore, a shorter exposure time.

[0153] Example 4

[0154] The shapes of the components in the lens system 200 of this embodiment 4 can be seen in [reference]. Figure 12 As shown. In this embodiment 4, the focal length, radius of curvature, thickness, refractive index, and dispersion coefficient of the first lens 210 and the second lens 220 in the lens system 200 can be designed using the corresponding proportions in Table 10 below. The radius of curvature, thickness, material, and conic coefficient of each surface S1 to S10 in the lens system 200 can be the parameters corresponding to those in Table 11 below, and the aspherical higher-order coefficients of the aspherical surfaces in S1 to S10 can be the parameters shown in Table 12 below.

[0155] Table 10

[0156]

[0157]

[0158] Table 11

[0159]

[0160] Table 12

[0161]

[0162]

[0163] Based on the parameters shown in Tables 10 to 12, the parameters of the lens system 200 provided in this embodiment 4 are as follows: TTL = 3.661mm (distance from S2 to S10), f = 0.516mm, f1 = -1.844mm, f2 = 0.653mm, Fno = 1.65, FOV = 123.3°.

[0164] Figures 13 to 14 The images shown are, in order, the astigmatism and distortion curves and the magnitude (MTF) graph of the optical transfer function of the lens system 200 provided in Embodiment 4. Figure 10 Figure (a) in the figure is an astigmatism curve. Figure 10 Figure (b) in the figure is a distortion curve.

[0165] from Figures 13 to 14The simulation diagram shows that the maximum object height Y of the lens system 200 is 4.74 mm, and the maximum distortion is approximately -2%. Furthermore, the lens system 200 can have a large FOV of 123.3°, which increases the object-side field of view of the lens system 200.

[0166] Example 5

[0167] The shapes of the components in the lens system 200 of this embodiment 5 can be seen in [reference]. Figure 15 As shown. In this embodiment 5, the focal length, radius of curvature, thickness, refractive index, and dispersion coefficient of the first lens 210 and the second lens 220 in the lens system 200 can be designed using the corresponding proportions in Table 13 below. The radius of curvature, thickness, material, and conic coefficient of each surface S1 to S10 in the lens system 200 can be the parameters corresponding to those in Table 14 below, and the aspherical higher-order coefficients of the aspherical surfaces in S1 to S10 can be the parameters shown in Table 15 below.

[0168] Table 13

[0169]

[0170]

[0171] Table 14

[0172]

[0173] Table 15

[0174] surface A4 A6 A8 A10 A12 S3 3.64E+00 -1.48E+01 3.34E+01 -7.81E+00 -1.00E+02 S4 2.00E+01 9.12E+01 -1.55E+04 3.74E+05 -3.94E+06 S6 -1.27E+01 6.57E+02 -1.75E+04 8.52E+04 5.20E+06 S7 -7.81E+00 5.07E+02 -1.29E+04 2.06E+05 -1.87E+06 surface A14 A16 A18 A20 S3 1.36E+02 2.69E+01 -9.67E+01 1.51E+01 S4 1.43E+07 6.96E+07 -7.38E+08 1.71E+09 S6 -3.90E+07 -1.07E+09 -1.90E+10 4.73E+11 S7 8.40E+06 1.12E+06 -1.67E+08 4.10E+08

[0175] Based on the parameters shown in Tables 13 to 15, the parameters of the lens system 200 provided in this embodiment 5 are as follows: TTL = 3.710mm (distance from S2 to S10), f = 0.476mm, f1 = -2.262mm, f2 = 0.602mm, Fno = 1.75, FOV = 127.65°.

[0176] Figures 16 to 17 The images shown are, in order, the astigmatism and distortion curves and the magnitude (MTF) graph of the optical transfer function of the lens system 200 provided in Embodiment 5. Figure 16 Figure (a) in the figure is an astigmatism curve. Figure 13 Figure (b) in the figure is a distortion curve.

[0177] from Figures 16 to 17The simulation diagram shows that the maximum object height Y of the lens system 200 is 5.66 mm, and the maximum distortion is approximately -3%. Furthermore, the lens system 200 can also have a large FOV of 127.65°, which increases the object-side field of view of the lens system 200.

[0178] In summary, in the several illustrative embodiments provided in this application, by designing the parameters of each lens in the lens system 200, the lens system 200 can have better imaging performance. Specifically, the lens system 200 can have a large FOV, a small F number, and small distortion.

[0179] In addition to the lens system 200 described above, this application embodiment also provides a fingerprint recognition device.

[0180] Figure 18 A schematic block diagram of a fingerprint recognition device 300 provided in an embodiment of this application is shown, such as... Figure 18 As shown, the fingerprint recognition device 300 may include a lens system 200 and a fingerprint image sensor 310.

[0181] The lens system 200 can be any of the lens systems described in the above embodiments. The fingerprint image sensor 310 is disposed below the lens system 200 and is used to receive the fingerprint light signal transmitted by the lens system 200 and process the fingerprint light signal to obtain a fingerprint image.

[0182] Specifically, the fingerprint image sensor 310 can be disposed on the imaging surface of the lens system 200. In other words, the surface of the fingerprint image sensor 310 can be the imaging surface of the lens system 200.

[0183] The fingerprint light signal transmitted through the lens system 200 is a light signal that has been reflected or scattered by the finger, and therefore carries fingerprint information. The fingerprint image sensor 310 can convert the fingerprint light signal into an electrical signal, thereby forming a fingerprint image with fingerprint information.

[0184] Figure 19 A schematic structural diagram of a fingerprint recognition device 300 provided in an embodiment of this application is shown.

[0185] like Figure 19 As shown, the fingerprint recognition device 300 is located below the display screen 20. The display screen 20 can provide a light source for the fingerprint recognition device 300. Specifically, when a user presses their finger on the display screen 20, the display screen 20 can emit a light source signal to the user's finger. After being reflected or scattered by the finger, the light source signal forms a fingerprint light signal carrying fingerprint information.

[0186] The fingerprint recognition device 300 may include a lens system 200 and a bracket 340 for mounting the lens system 200. Optionally, the first lens 210 and the second lens 220 in the lens system 200 may be interference-fitted into the bracket 340 to improve the overall reliability of the lens system 200.

[0187] Specifically, the bracket 340 can be used to control the defocus and eccentricity accuracy of the first lens 210 and the second lens 220 in the lens system 200, thereby improving the imaging performance of the lens system 200. The bracket 340 can be formed by metal stamping or by other methods, and this application does not specifically limit the method.

[0188] In addition to the lens system 200 and the bracket 340, the fingerprint recognition device 300 also includes a circuit board 320, which is disposed below the fingerprint image sensor 310 and electrically connected to the fingerprint image sensor 310. The circuit board 320 is used to realize the transmission of electrical signals between the fingerprint recognition device 300 and the outside.

[0189] Optionally, the circuit board 320 can be a flexible printed circuit (FPC), and a reinforcing plate 330 can be provided below the FPC to support and reinforce it, thereby improving the mechanical strength and reliability of the entire fingerprint recognition device 300. As an example, the reinforcing plate 330 can be a steel plate or a printed circuit board (PCB), etc.

[0190] The lower surface of the fingerprint image sensor 310 can be bonded to the circuit board 320 using chip bonding adhesive to achieve a structural connection between the fingerprint image sensor 310 and the circuit board 320. Alternatively, the fingerprint image sensor 310 can be electrically connected to the circuit board 320 via wire bonding or other electrical connection methods, facilitating the transmission of relevant electrical signals from the fingerprint image sensor 310 to external electronic devices via the circuit board 320.

[0191] See also Figure 19 As shown, an IR filter 230 may be provided on the upper surface of the fingerprint image sensor 310. The IR filter 230 can be attached to the upper surface of the fingerprint image sensor 310 by means of filter adhesive.

[0192] In this embodiment, the IR filter 230, the fingerprint image sensor 310, the circuit board 320, and the reinforcing plate 330 are connected together by an adhesive layer to form a fingerprint image sensor module. This module can be bonded to the bracket 340 on which the lens system 200 is mounted by the adhesive layer to form an integrated fingerprint recognition device 300, thereby facilitating the installation of the integrated fingerprint recognition device 300 below the display screen 20.

[0193] This application also provides a terminal device, such as... Figure 20 As shown, the terminal device 400 may include the fingerprint recognition device 300 and the display screen 20 in the above embodiment. The fingerprint recognition device 300 is disposed below the display screen 20 to realize under-display fingerprint recognition.

[0194] Optionally, in some embodiments, the fingerprint recognition device 300 may be disposed in the mid-frame of the terminal device 400, thereby realizing the placement of the fingerprint recognition device 300 below the display screen 20 of the terminal device 400.

[0195] Optionally, in order to protect the display screen 20, the lower surface of the display screen 20 may be provided with a protective layer or heat dissipation layer such as foam and copper foil. The area of ​​the foam and copper foil above the lens system 200 in the fingerprint recognition device 300 is opened so that the light signal including fingerprint information can enter the lens system 200, thereby enabling the fingerprint recognition device 300 to perform the fingerprint recognition function.

[0196] As an example and not a limitation, the terminal device 400 can be a mobile phone, tablet computer, laptop computer, desktop computer, in-vehicle electronic device, or wearable smart device, etc. The wearable smart device includes those that are fully functional, large in size, and can achieve complete or partial functions without relying on a smartphone, such as smartwatches or smart glasses, as well as those that focus on only a certain type of application function and need to be used in conjunction with other devices such as smartphones, such as various smart bracelets and smart jewelry for vital sign monitoring.

[0197] It should be noted that, without conflict, the various embodiments and / or technical features described in this application can be arbitrarily combined with each other, and the resulting technical solutions should also fall within the protection scope of this application.

[0198] For ease of explanation, in the various embodiments of this application, the same reference numerals denote the same components, and for brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0199] Unless otherwise stated, all technical and scientific terms used in the embodiments of this application have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items.

[0200] It should be understood that the specific examples in the embodiments of this application are only for the purpose of helping those skilled in the art to better understand the embodiments of this application, and are not intended to limit the scope of the embodiments of this application. Those skilled in the art can make various improvements and modifications based on the above embodiments, and all such improvements or modifications fall within the protection scope of this application.

[0201] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A lens system characterized by comprising: The lens system is composed of a first lens and a second lens arranged in sequence from an object side to an image side; The first lens is a negative lens, the first lens has a concave surface towards the object side and a convex surface towards the image side, and at least one surface of the first lens is aspherical; The second lens is a positive lens, the second lens has a convex surface towards the image side, and at least one surface of the second lens is aspherical; a focal length of the first lens a focal length of the second lens satisfies ; a focal length of the first lens a radius of curvature of a surface of the first lens facing the object side satisfies ; and / or, a focal length of the first lens a radius of curvature of a surface of the first lens facing the image side satisfies .

2. The lens system according to claim 1, characterized by The lens system is arranged below a display screen of an electronic device, a maximum image height H of the lens system on an imaging plane , a focal length f and a distance TTL from a lower surface of the display screen to the imaging plane satisfy .

3. The lens system according to claim 1, characterized by a focal length of the lens system a focal length of the first lens satisfies ; and / or, a focal length of the lens system a focal length of the second lens satisfies .

4. The lens system according to any one of claims 1 to 3, characterized in that, a focal length of the second lens a radius of curvature of a surface of the second lens facing the object side satisfies ; and / or, a focal length of the second lens a radius of curvature of a surface of the second lens facing the image side satisfies .

5. The lens system according to any one of claims 1 to 3, characterized by, a radius of curvature of a surface of the first lens facing the object side a radius of curvature of a surface of the first lens facing the image side satisfies ; and / or, a radius of curvature of a surface of the second lens facing the object side a radius of curvature of a surface of the second lens facing the image side satisfies .

6. The lens system according to any one of claims 1 to 3, characterized in that, a thickness of the first lens on the optical axis a thickness of the second lens on the optical axis satisfies .

7. The lens system according to any one of claims 1 to 3, characterized in that, a refractive index of the first lens satisfies a dispersion coefficient of the first lens satisfies ; and / or, The refractive index of the second lens satisfies The dispersion coefficient of the second lens satisfies .

8. The lens system according to any one of claims 1 to 3, characterized in that, The lens system further comprises: a diaphragm arranged between the first lens and the second lens.

9. The lens system according to any one of claims 1 to 3, characterized in that, The lens system further comprises: an infrared light filter arranged on a side of the second lens towards the image side.

10. The lens system according to claim 9, characterized in that, The lens system further comprises: a filter adhesive for adhering the infrared light filter to an imaging surface of the lens system.

11. The lens system according to any one of claims 1 to 3, characterized in that, The system parameters of the lens system satisfy at least one of the following conditions: a field of view FOV greater than 110°; an F number less than 1.8; distortion less than 5%.

12. A fingerprint recognition device, characterized by It comprises: a fingerprint image sensor and a lens system as claimed in any one of claims 1 to 11; wherein the fingerprint image sensor is arranged below the lens system to receive a fingerprint light signal transmitted by the lens system and process the fingerprint light signal to obtain a fingerprint image.

13. The fingerprint recognition apparatus according to claim 12, wherein, The fingerprint recognition device further comprises a bracket. The lens system is interference fitted in the bracket.

14. The fingerprint recognition apparatus according to claim 12, wherein, The fingerprint recognition device further comprises a circuit board. The circuit board is arranged below the fingerprint image sensor and electrically connected to the fingerprint image sensor, and the circuit board is used to realize electrical signal transmission between the fingerprint recognition device and the outside.

15. A terminal device, comprising: It comprises: a display screen and a fingerprint recognition device as claimed in any one of claims 12 to 14; wherein the fingerprint recognition device is arranged below the display screen to realize under-screen fingerprint recognition.

Images