Optical lens, optical fingerprint module and electronic device

Abstract

The application relates to the optical field, in particular to an optical lens, an optical fingerprint module and an electronic device. The optical lens is configured between a display screen and an imaging surface. The optical lens comprises three optical lenses. The three optical lenses are a first lens, a second lens and a third lens arranged in sequence along an optical axis of the optical lens from the display screen to the imaging surface. The optical lens satisfies 1 <= TTL / airgap <= 1.4. According to the optical lens, the miniaturization of the optical lens can be realized under the condition of ensuring the imaging performance, and the cost is reduced.

Description

Technical Field

[0001] This application relates to the field of optics, and in particular to an optical lens, an optical fingerprint module, and an electronic device. Background Technology

[0002] With the rapid development of smart consumer products, under-display optical fingerprint recognition technology has gradually become an important function of smartphones and other devices. The core of this technology lies in integrating the screen display area with the fingerprint recognition function, thereby improving user experience and optimizing device design. In recent years, smartphone manufacturers have continuously pursued thinner and lighter designs and better display effects, leading to a gradual decrease in screen transmittance and more compact internal spaces. This design trend places higher demands on under-display optical fingerprint recognition technology, requiring a more miniaturized design within limited space while ensuring higher performance and reliability of the fingerprint recognition system.

[0003] The information disclosed in this background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not form any part of the prior art and does not form prior art that may be taught to those skilled in the art. Utility Model Content

[0004] This utility model summary is provided to introduce, in a simplified form, the selected concepts that will be further described in the detailed embodiments below. This utility model summary is not intended to identify key or essential features of the subject matter to be protected, nor is it intended to help determine the scope of the subject matter to be protected.

[0005] To address the issue of excessively large fingerprint lenses occupying too much space in the market, this invention provides an optical lens, an optical fingerprint module, and an electronic device that can achieve miniaturization while maintaining imaging performance.

[0006] The technical solution adopted in this embodiment of the utility model is as follows:

[0007] The first aspect of this utility model provides an optical lens for being disposed between a display screen and an imaging surface. The optical lens includes three optical lenses, which are a first lens, a second lens, and a third lens arranged sequentially along the optical axis of the optical lens from the display screen to the imaging surface.

[0008] The optical lens satisfies: 1 ≤ TTL / airgap ≤ 1.4;

[0009] airgap is the distance on the optical axis from the surface of the display screen closest to the optical lens to the object surface of the first lens;

[0010] TTL is the distance from the object surface of the first lens to the imaging surface on the optical axis.

[0011] Furthermore, the first lens has negative optical power, while the second and third lenses both have positive optical power.

[0012] Furthermore, the object surface of the first lens is concave, and the image surface of the first lens is concave; the object surface of the second lens is convex, and the image surface of the second lens is convex; the object surface of the third lens is convex, and the image surface of the third lens is convex.

[0013] Furthermore, the optical lens also includes an aperture stop, which is disposed between the first lens and the second lens.

[0014] Furthermore, the optical lens satisfies: 4.5 ≤ TTL / f ≤ 6;

[0015] TTL is the distance from the object surface of the first lens to the imaging surface on the optical axis, and f is the effective focal length of the optical lens.

[0016] Furthermore, the optical lens satisfies the following condition: TTL ≤ 1.7mm;

[0017] TTL is the distance from the object surface of the first lens to the imaging surface on the optical axis.

[0018] Furthermore, the optical lens satisfies: fov ≥ 120°, where fov is the field of view of the optical lens.

[0019] Furthermore, the optical lens satisfies: 1.8 ≤ ImgH / f ≤ 2;

[0020] ImgH is the image height corresponding to half of the maximum field of view of the optical lens;

[0021] f is the effective focal length of the optical lens.

[0022] Furthermore, the optical lens satisfies: 6.5≤ObjH / ImgH≤8;

[0023] ObjH is the object height corresponding to half of the maximum field of view of the optical lens;

[0024] ImgH is the image height corresponding to half of the maximum field of view of the optical lens.

[0025] Furthermore, the optical lens satisfies: 2≤(CT1+CT2+CT3) / f≤3.5;

[0026] CT1 is the thickness of the first lens on the optical axis;

[0027] CT2 is the thickness of the second lens along the optical axis;

[0028] CT3 is the thickness of the third lens on the optical axis.

[0029] Furthermore, the optical lens satisfies: 5≤(f2+f3) / f≤6;

[0030] f2 is the effective focal length of the second lens;

[0031] f3 is the effective focal length of the third lens;

[0032] f is the effective focal length of the optical lens.

[0033] Furthermore, the optical lens satisfies: f / EPD≤1.8;

[0034] f is the effective focal length of the optical lens;

[0035] EPD is the entrance pupil diameter of the optical lens.

[0036] Furthermore, BFL / TTL ≤ 0.3;

[0037] BFL is the distance from the image-side surface of the third lens to the imaging surface on the optical axis;

[0038] TTL is the distance from the object surface of the first lens to the imaging surface on the optical axis.

[0039] Furthermore, the optical lens satisfies: 1.5≤ND1≤1.6, 20≤VD1≤70;

[0040] Wherein, ND1 is the refractive index of the first lens, and VD1 is the Abbe number of the first lens.

[0041] Furthermore, the optical lens satisfies: 1.5≤ND2≤1.6, 20≤VD2≤70;

[0042] Wherein, ND2 is the refractive index of the second lens, and VD2 is the Abbe number of the second lens.

[0043] Furthermore, the optical lens satisfies: 1.5≤ND3≤1.6, 20≤VD3≤70;

[0044] Wherein, ND3 is the refractive index of the second lens, and VD3 is the Abbe number of the second lens.

[0045] A second aspect of this invention provides an optical fingerprint module, including an image sensor and an optical lens, wherein the image sensor is disposed on the image side of the optical lens and forms the imaging surface.

[0046] A third aspect of this invention provides an electronic device, including a display screen and an optical fingerprint module as described above, wherein the display screen is disposed on the object side of the optical fingerprint module.

[0047] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0048] The optical lens provided by this utility model is used to be disposed between a display screen and an imaging surface. The optical lens includes three optical lenses, which are a first lens, a second lens, and a third lens arranged sequentially along the optical axis of the optical lens from the display screen to the imaging surface. The optical lens satisfies 1 ≤ TTL / airgap ≤ 1.4. According to the optical lens of this application, miniaturization of the optical lens can be achieved while ensuring imaging performance, and costs can be reduced.

[0049] This utility model also provides an optical fingerprint module, which includes an image sensor and an optical lens as described above. The image sensor is disposed on the image side of the optical lens. Since the optical fingerprint module includes the optical lens, it also has the beneficial effects of an optical lens, and can be adapted to smaller electronic devices while ensuring imaging performance.

[0050] This utility model also provides an electronic device, which includes a display screen and an optical fingerprint module as described above, wherein the display screen is disposed on the object side of the optical lens; the electronic device includes an optical fingerprint module disposed with the aforementioned optical lens, and thus also has the beneficial effects of the optical lens. Attached Figure Description

[0051] 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.

[0052] Figure 1 This is a diagram illustrating a first example of an electronic device with an optical lens.

[0053] Figure 2 Presentation Figure 1 The astigmatism curve of the optical lens is shown.

[0054] Figure 3 Presentation Figure 1 The distortion curve of the optical lens is shown.

[0055] Figure 4 Presentation Figure 1 The MTF curve of the optical lens is shown.

[0056] Figure 5 Presentation Figure 1 The relative illumination curve of the optical lens is shown.

[0057] Figure 6 This is a diagram illustrating a second example of an electronic device with an optical lens.

[0058] Figure 7 Presentation Figure 6 The astigmatism curve of the optical lens is shown.

[0059] Figure 8 Presentation Figure 6 The distortion curve of the optical lens is shown.

[0060] Figure 9 Presentation Figure 6 The MTF curve of the optical lens is shown.

[0061] Figure 10 Presentation Figure 6 The relative illumination curve of the optical lens is shown.

[0062] Figure 11 This is a diagram illustrating a third example of an electronic device with an optical lens.

[0063] Figure 12 Presentation Figure 11 The astigmatism curve of the optical lens is shown.

[0064] Figure 13 Presentation Figure 11 The distortion curve of the optical lens is shown.

[0065] Figure 14 Presentation Figure 11 The MTF curve of the optical lens is shown.

[0066] Figure 15 Presentation Figure 11 The relative illumination curve of the optical lens is shown.

[0067] Figure label:

[0068] exist Figure 1 In the middle: 100-display screen; 110-first lens; 120-second lens; 130-third lens; 140-filter; 150-image sensor; STO-aperture.

[0069] exist Figure 6 In the middle: 200-display screen; 210-first lens; 220-second lens; 230-third lens; 240-filter; 250-image sensor; STO-aperture;

[0070] exist Figure 11 In the middle: 300-display screen; 310-first lens; 320-second lens; 330-third lens; 340-filter; 350-image sensor; STO-aperture. Detailed Implementation

[0071] The following detailed embodiments are provided to help the reader gain a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, various modifications, alterations, and equivalents of the methods, apparatus, and / or systems described herein will be apparent after understanding the disclosure of this application. For example, the order of operations described herein is merely illustrative and is not limited to the order set forth herein; changes that will be apparent after understanding the disclosure of this application are possible, except for operations that must occur in a specific order. Furthermore, for clarity and brevity, descriptions of features known in the art may be omitted.

[0072] The features described herein may be implemented in different forms and are not to be construed as being limited to the examples described herein. Rather, the examples described herein have been provided merely to illustrate some of the many feasible ways in which the methods, devices, and / or systems described herein will be apparent upon understanding the disclosure of this application.

[0073] The first aspect of this application provides an optical lens that enables miniaturization while maintaining imaging performance.

[0074] In the embodiments of this application, the first lens is the lens closest to the object (or subject), and the second lens is the lens closest to the imaging surface (or image sensor). Furthermore, in this application, the following parameters are expressed in millimeters (mm): radius of curvature, effective radius and thickness of the lens, distance from the object-side surface of the first lens to the imaging surface (TTL), image height corresponding to half the maximum field of view of the optical lens (ImgH), image height corresponding to half the maximum field of view of the optical lens (ObjH), entrance pupil diameter of the optical lens (EPD), distance from the image-side surface of the second lens to the imaging surface (BFL), distance from the side of the display screen closest to the optical lens to the object-side surface of the first lens (airgap), and focal length.

[0075] Furthermore, the lens thickness, the distance between lenses, and the TTL are distances measured based on the optical axis of the lens. Additionally, in the description of the lens shape, a statement that one surface of the lens is convex along the optical axis means that the paraxial region of the corresponding surface is convex, and a statement that one surface of the lens is concave along the optical axis means that the paraxial region of the corresponding surface is concave. Therefore, even when one surface of the lens is described as convex, the edge portion of said one surface may be concave. Similarly, even when one surface of the lens is described as concave, the edge portion of said one surface may be convex.

[0076] The optical lens provided in this application is configured between the display screen and the imaging surface. Thus, when a target biometric comes into contact with the fingerprint collection area on the surface of the display screen away from the optical lens, a light source emits light towards the fingerprint collection area. This light is reflected by the target biometric and received by the optical lens, forming an image on the imaging surface, thereby achieving biometric data collection. It should be understood that biometric features include, but are not limited to, fingerprint features, palm print features, iris features, and facial features.

[0077] Please refer to Figure 1 , Figure 6 or Figure 11 As shown, the optical lens includes three optical lenses; for example, the optical lenses include a first lens, a second lens, and a third lens arranged sequentially along the optical axis of the optical lens from the object side to the imaging plane. In other words, the light reflected by the target organism passes through the first lens, the second lens, and the third lens in sequence before being imaged on the imaging plane.

[0078] Meanwhile, the optical lens satisfies 1≤TTL / airgap≤1.4, where airgap is the distance on the optical axis from the surface of the display screen closest to the optical lens to the object surface of the first lens, and TTL is the distance on the optical axis from the object surface of the first lens to the imaging surface.

[0079] Please continue to refer to Figure 1 , Figure 6 or Figure 11 As shown, the first lens has negative optical power, the second lens has positive optical power, and the third lens has positive optical power.

[0080] Preferably, such as Figure 1 , Figure 6 or Figure 11As shown, for the first lens, its object-side surface is concave along the optical axis, and its image-side surface is convex along the optical axis; for the second lens, its object-side surface is convex along the optical axis, and its image-side surface is convex along the optical axis; for the third lens, its object-side surface is convex along the optical axis, and its image-side surface is convex along the optical axis. This configuration allows for further reduction in the size of the optical lens while still enabling its application under the screen. This facilitates a reduction in the thickness of the device housing the optical lens, achieving a slimmer and lighter design. Simultaneously, it effectively ensures that the optical lens maintains excellent imaging performance.

[0081] Preferably, the object-side and image-side surfaces of the first lens, the second lens, and the third lens are all aspherical surfaces, and each aspherical surface can be described by the following expression 1:

[0082] (1)

[0083] Where R is the radius of curvature, K is the conic coefficient, A1-A20 are the higher-order coefficients of the aspherical surface, X is the effective radius value of the corresponding surface of the lens, and Z is the sagitta of the aspherical surface.

[0084] Preferably, the optical lens may further include an aperture stop; for example, such as Figure 1 , Figure 6 or Figure 11 As shown, the aperture stop is positioned between the first lens and the second lens. This position allows for better control of the amount of light entering the sensor, improving imaging quality and achieving a wide-angle effect to receive light at large angles, thereby expanding the fingerprint acquisition area.

[0085] Preferably, the optical lens may also include a filter; for example, such as Figure 1 , Figure 6 or Figure 11 As shown, the filter is positioned on the image side of the third lens, that is, between the third lens and the imaging plane. The filter is used to block light rays other than the target wavelength and to allow some or all of the infrared optical fibers with the target wavelength to pass through. Therefore, by setting a filter, the image sensor located on the imaging plane receives less light of non-target wavelengths, thereby effectively reducing the possibility of interference from ambient light (such as sunlight or artificial light) and improving recognition accuracy.

[0086] The second aspect of this application relates to an optical fingerprint module, which includes an image sensor and the optical lens described in the first aspect above. The image sensor is disposed on the image side of the optical lens. The image sensor forms the imaging surface of the optical lens; for example, the surface of the photosensitive pixel array of the image sensor forms the imaging surface.

[0087] A third aspect of this application relates to an electronic device comprising a display screen and an optical fingerprint module as described above, the display screen being disposed on the object side of an optical lens. Here, the electronic device may be a portable or mobile terminal such as a mobile phone, tablet computer, or gaming device. In the electronic device, the optical fingerprint module is disposed below the display screen and is used to receive a light beam carrying fingerprint information. The optical lens in the optical fingerprint module is used to guide the incident light beam to an image sensor, which converts the light beam into a fingerprint signal and obtains a fingerprint image based on the fingerprint signal. In an embodiment, the display screen can provide a light source for the finger, illuminating the finger and reflecting the light beam carrying the light signal.

[0088] In addition to satisfying the above-mentioned condition of 1≤TTL / airgap≤1.4, the optical lenses, optical fingerprint modules, and electronic devices involved in this disclosure may also satisfy the following conditional expression:

[0089] In some embodiments, 4.5 ≤ TTL / f ≤ 6 is satisfied.

[0090] In some embodiments, the TTL is ≤ 1.7 mm.

[0091] In some embodiments, fov ≥ 120° is satisfied.

[0092] In some embodiments, 1.8 ≤ ImgH / f ≤ 2 is satisfied.

[0093] In some embodiments, 6.5 ≤ ObjH / ImgH ≤ 8 is satisfied.

[0094] In some embodiments, 2≤(CT1+CT2+CT3) / f≤3.5 is satisfied.

[0095] In some embodiments, 5≤(f2+f3) / f≤6 is satisfied.

[0096] In some embodiments, f / EPD ≤ 1.8 is satisfied.

[0097] In some embodiments, BFL / TTL ≤ 0.3 is satisfied.

[0098] In some embodiments, 1.5 ≤ ND1 ≤ 1.6 is satisfied.

[0099] In some embodiments, 1.5 ≤ ND2 ≤ 1.6 is satisfied.

[0100] In some embodiments, 1.5 ≤ ND3 ≤ 1.6 is satisfied.

[0101] In some embodiments, 20 ≤ VD1 ≤ 70 is satisfied.

[0102] In some embodiments, 20 ≤ VD2 ≤ 70 is satisfied.

[0103] In some embodiments, 20 ≤ VD3 ≤ 70 is satisfied.

[0104] In the above expression:

[0105] TTL is the distance from the object surface of the first lens to the imaging surface on the optical axis; airgap is the distance from the side surface of the display screen closest to the optical lens to the object surface of the first lens on the optical axis; f is the effective focal length of the optical lens; fov is the field of view of the optical lens; ImgH is the image height corresponding to half of the maximum field of view of the optical lens; ObjH is the object height corresponding to half of the maximum field of view of the optical lens; CT1 is the thickness of the first lens on the optical axis; CT2 is the thickness of the second lens on the optical axis. Thickness on the optical axis; CT3 is the thickness of the third lens on the optical axis; f2 is the effective focal length of the second lens; f3 is the effective focal length of the third lens; EPD is the entrance pupil diameter of the optical lens; BFL is the distance on the optical axis from the image surface of the third lens to the imaging plane; ND1 is the refractive index of the first lens, VD1 is the Abbe number of the first lens; ND2 is the refractive index of the second lens, VD2 is the Abbe number of the second lens; ND3 is the refractive index of the second lens, VD3 is the Abbe number of the second lens.

[0106] Here, according to 1≤TTL / airgap≤1.4, it is beneficial to ensure the illumination of the optical lens, improve its imaging quality, and facilitate the miniaturization of the optical lens.

[0107] Furthermore, based on 4.5≤TTL / f≤6 and TTL≤1.7mm, it is beneficial to achieve miniaturization of optical lenses, so as to better adapt to the assembly requirements of small spaces under the screen.

[0108] Furthermore, based on fov≥120°, the wide-angle characteristics of the optical lens can be guaranteed, the imaging range of the optical lens can be improved, and thus the recognition capability of biometric features can be enhanced.

[0109] Furthermore, based on 1.8≤ImgH / f≤2, the wide-angle characteristics of the optical lens can be guaranteed, which is beneficial to reducing the size of the image sensor located on the imaging plane, thereby saving costs.

[0110] Furthermore, based on 6.5≤ObjH / ImgH≤8, the optical lens can be guaranteed to recognize biometric features such as fingerprints, and can also guarantee the imaging of a small object with a wide angle, which is conducive to miniaturization.

[0111] Furthermore, according to 2≤(CT1+CT2+CT3) / f≤3.5, the lens of the optical lens can have a smaller thickness, which is beneficial for controlling the overall optical length of the optical lens.

[0112] Furthermore, according to 5≤(f2+f3) / f≤6, each lens of the optical lens can have a reasonable optical power, which is beneficial to reduce the sensitivity of the optical lens and improve the imaging quality of the optical lens.

[0113] Furthermore, based on f / EPD≤1.8, it is beneficial to increase the amount of light entering the center of the optical lens, reduce the unlocking time of the fingerprint optical lens, and improve the unlocking capability.

[0114] Furthermore, the BFL / TTL ≤ 0.3 facilitates the miniaturization of optical lenses, enabling them to have a larger imaging range.

[0115] Furthermore, based on 1.5≤ND1≤1.6, 20≤VD1≤70, 1.5≤ND2≤1.6, 20≤VD2≤70, and 1.5≤ND3≤1.6, 20≤VD3≤70, it is beneficial to control the center thickness of the optical lens, reduce the processing difficulty of the lens, thereby reducing the cost of the optical lens, and at the same time, it is beneficial to eliminate chromatic aberration of the optical lens and improve image quality.

[0116] Next, an electronic device based on several examples will be described.

[0117] First, refer to Figure 1 Describe the electronic device based on the first example.

[0118] The electronic device includes a display screen 100 and an optical fingerprint module. The display screen 100 is disposed on the object side of the optical fingerprint module. The optical fingerprint module includes an optical lens and an image sensor 150, which is disposed on the image side of the optical lens.

[0119] The optical lens according to the first example includes a first lens 110, a second lens 120, and a third lens 130. An aperture stop STO is provided between the first lens 110 and the second lens 120, and a filter 140 is provided on the image side of the third lens 130, i.e., between the third lens 130 and the image sensor 150.

[0120] The first lens has negative optical power, with its object surface concave along the optical axis and its image surface convex along the optical axis; the second lens has positive optical power, with its object surface convex along the optical axis and its image surface convex along the optical axis; the third lens has positive optical power, with its object surface convex along the optical axis and its image surface convex along the optical axis.

[0121] In the optical lens of the first example, the effective focal length of the first lens is f1 = -0.662 mm, the effective focal length of the second lens is f2 = 1.232 mm, the effective focal length of the third lens is f3 = 0.447 mm, and the total focal length (effective focal length) of the optical lens is f = 0.295 mm; the field of view of the optical lens is fov = 123.73°, TTL = 1.662 mm, TTL / f = 5.634, and ImgH / f = 1.80. 7, TTL / airgap=1.251, ObjH / ImgH=7.338, (CT1+CT2+CT3) / f=3.051, (f2+f3) / f=5.691, f / E PD=1.475, BFL / TTL=0.289; ND1=1.54, VD1=55.8, ND2=1.54, VD2=55.8, ND3=1.54, VD3=55.8.

[0122] Table 1

[0123]

[0124] Here, the conic coefficients are the coefficients of the higher-order terms in the above formula.

[0125] In this context, OBJ represents the object or subject, S01 and S02 represent, for example, the upper and lower surfaces of a display screen, respectively, S1 and S2 represent the object and image surfaces of the first lens, STO represents the aperture stop, S3 and S4 represent the object and image surfaces of the second lens, S5 and S6 represent the object and image surfaces of the third lens, S7 and S8 represent the object and image surfaces of the filter, and S9 represents the imaging surface.

[0126] Figure 2 The astigmatism curves of the optical lens of the first example are presented, which represent the curves of meridional image plane curvature and sagittal image plane curvature at different image heights at 0.537 nm, 0.58 nm and 0.460 nm. Figure 3 The distortion curves of the optical lens of the first example are presented, which show the distortion curves at different image heights at 0.537nm, 0.58nm and 0.460nm; Figure 4 The MTF curves of the optical lens of the first example at different spatial frequencies with different image heights are presented. Figure 5 The relative illumination curves of the optical lens of the first example are presented. Table 1 presents the lens characteristics according to the optical lens of the first example.

[0127] Next, we will refer to Figure 6 Describe the electronic device based on the second example.

[0128] The electronic device includes a display screen 200 and an optical fingerprint module. The display screen 200 is disposed on the object side of the optical fingerprint module. The optical fingerprint module includes an optical lens and an image sensor 250, which is disposed on the image side of the optical lens.

[0129] The optical lens according to the second example includes a first lens 210, a second lens 220, and a third lens 230. An aperture stop STO is provided between the first lens 210 and the second lens 220, and a filter 240 is provided on the image side of the third lens 230, i.e., between the third lens 230 and the image sensor 250.

[0130] The first lens has negative optical power, with its object surface concave along the optical axis and its image surface convex along the optical axis; the second lens has positive optical power, with its object surface convex along the optical axis and its image surface convex along the optical axis; the third lens has positive optical power, with its object surface convex along the optical axis and its image surface convex along the optical axis.

[0131] In the optical lens of the second example, the effective focal length of the first lens is f1 = -0.751 mm, the effective focal length of the second lens is f2 = 1.207 mm, the effective focal length of the third lens is f3 = 0.513 mm, and the total focal length (effective focal length) of the optical lens is f = 0.343 mm; the field of view of the optical lens is fov = 128.37°, TTL = 1.663 mm, TTL / f = 4.849, and ImgH / f = 1.93. 3. TTL / airgap=1.240, ObjH / ImgH=6.637, (CT1+CT2+CT3) / f=2.656, (f2+f3) / f=5.016, f / E PD=1.715, BFL / TTL=0.290; ND1=1.54, VD1=55.8, ND2=1.54, VD2=55.8, ND3=1.54, VD3=55.8.

[0132] Table 2

[0133]

[0134] Here, the conic coefficients are the coefficients of the higher-order terms in the above formula.

[0135] In this context, OBJ represents the object or subject, S01 and S02 represent, for example, the upper and lower surfaces of a display screen, respectively, S1 and S2 represent the object and image surfaces of the first lens, STO represents the aperture stop, S3 and S4 represent the object and image surfaces of the second lens, S5 and S6 represent the object and image surfaces of the third lens, S7 and S8 represent the object and image surfaces of the filter, and S9 represents the imaging surface.

[0136] Figure 7The astigmatism curves of the second example optical lens are presented, which represent the curves of meridional image plane curvature and sagittal image plane curvature at different image heights at 0.537 nm, 0.58 nm and 0.460 nm. Figure 8 The distortion curves of the optical lens in the second example are presented, showing the distortion curves at different image heights of 0.537nm, 0.58nm and 0.460nm; Figure 9 The MTF curves of the second example optical lens at different image heights and spatial frequencies are presented. Figure 10 The relative illumination curves of the optical lens of the second example are presented. Table 2 presents the lens characteristics according to the optical lens of the second example.

[0137] Next, we will refer to Figure 11 Describe the electronic device based on the third example.

[0138] The electronic device includes a display screen 300 and an optical fingerprint module. The display screen 300 is disposed on the object side of the optical fingerprint module. The optical fingerprint module includes an optical lens and an image sensor 350. The image sensor 350 is disposed on the image side of the optical lens.

[0139] The optical lens according to the third example includes a first lens 310, a second lens 320, and a third lens 330. An aperture stop STO is provided between the first lens 310 and the second lens 320, and a filter 340 is provided on the image side of the third lens 330, i.e., between the third lens 330 and the image sensor 350.

[0140] The first lens has negative optical power, with its object surface concave along the optical axis and its image surface convex along the optical axis; the second lens has positive optical power, with its object surface convex along the optical axis and its image surface convex along the optical axis; the third lens has positive optical power, with its object surface convex along the optical axis and its image surface convex along the optical axis.

[0141] In the optical lens of the third example, the effective focal length of the first lens is f1 = -0.627 mm, the effective focal length of the second lens is f2 = 1.167 mm, the effective focal length of the third lens is f3 = 0.446 mm, and the total focal length (effective focal length) of the optical lens is f = 0.290 mm; the field of view of the optical lens is fov = 125°, TTL = 1.581 mm, TTL / f = 5.452, and ImgH / f = 1.838. , TTL / airgap=1.120, ObjH / ImgH=7.711, (CT1+CT2+CT3) / f=2.966, (f2+f3) / f=5.562, f / EP D=1.648, BFL / TTL=0.293; ND1=1.54, VD1=55.8, ND2=1.54, VD2=55.8, ND3=1.54, VD3=55.8.

[0142] Table 3

[0143]

[0144] Here, the conic coefficients are the coefficients of the higher-order terms in the above formula.

[0145] In this context, OBJ represents the object or subject, S01 and S02 represent, for example, the upper and lower surfaces of a display screen, respectively, S1 and S2 represent the object and image surfaces of the first lens, STO represents the aperture stop, S3 and S4 represent the object and image surfaces of the second lens, S5 and S6 represent the object and image surfaces of the third lens, S7 and S8 represent the object and image surfaces of the filter, and S9 represents the imaging surface.

[0146] Figure 12 The astigmatism curves of the optical lens in the third example are presented, which represent the curves of meridional image plane curvature and sagittal image plane curvature at different image heights at 0.537 nm, 0.58 nm and 0.460 nm. Figure 13 The distortion curves of the optical lens in the third example are presented, showing the distortion curves at different image heights of 0.537nm, 0.58nm, and 0.460nm. Figure 14 The MTF curves of the optical lens of the third example at different spatial frequencies with different image heights are presented. Figure 15 The relative illumination curves of the optical lens of the third example are presented. Table 3 presents the lens characteristics according to the optical lens of the third example.

[0147] Table 4 presents the values ​​of the conditional expressions for the optical lenses based on the first, second, and third examples.

[0148] Table 3

[0149]

[0150] Based on the above examples, it is possible to reduce costs while maintaining imaging performance.

[0151] While this disclosure includes specific examples, it will be apparent upon understanding the disclosure of this application that various changes in form and detail may be made to these examples without departing from the spirit and scope of the claims and their equivalents. The examples described herein are to be considered descriptive only and not for limiting purposes. The description of features or aspects in each example is to be considered applicable to similar features or aspects in other examples. Suitable results may be obtained if the described techniques are performed in a different order, and / or if components in the described system, architecture, apparatus, or circuit are combined in a different manner and / or if components in the described system, architecture, apparatus, or circuit are replaced or supplemented with other components or their equivalents. Therefore, the scope of this disclosure is not limited by the specific embodiments but by the claims and their equivalents, and all variations within the scope of the claims and their equivalents shall be construed as included in this disclosure.

Claims

1. An optical lens, characterized in that, The optical lens is configured between the display screen and the imaging surface. The optical lens includes three optical lenses, which are a first lens, a second lens, and a third lens arranged sequentially along the optical axis of the optical lens from the display screen to the imaging surface. The optical lens satisfies: 1 ≤ TTL / airgap ≤ 1.4; airgap is the distance on the optical axis from the surface of the display screen closest to the optical lens to the object surface of the first lens; TTL is the distance from the object surface of the first lens to the imaging surface on the optical axis.

2. The optical lens according to claim 1, characterized in that, The first lens has negative optical power, while the second and third lenses both have positive optical power.

3. The optical lens according to claim 1, characterized in that, The object surface of the first lens is concave, and the image surface of the first lens is concave; the object surface of the second lens is convex, and the image surface of the second lens is convex; the object surface of the third lens is convex, and the image surface of the third lens is convex.

4. The optical lens according to claim 1, characterized in that, The optical lens also includes an aperture stop, which is disposed between the first lens and the second lens.

5. The optical lens according to any one of claims 1 to 4, characterized in that, The optical lens satisfies: 4.5≤TTL / f≤6; TTL is the distance from the object surface of the first lens to the imaging surface on the optical axis, and f is the effective focal length of the optical lens.

6. The optical lens according to any one of claims 1 to 4, characterized in that, The optical lens meets the following requirements: TTL ≤ 1.7mm; TTL is the distance from the object surface of the first lens to the imaging surface on the optical axis.

7. The optical lens according to any one of claims 1 to 4, characterized in that, The optical lens satisfies the following condition: fov ≥ 120°, where fov is the field of view angle of the optical lens.

8. The optical lens according to any one of claims 1 to 4, characterized in that, The optical lens satisfies: 1.8 ≤ ImgH / f ≤ 2; ImgH is the image height corresponding to half of the maximum field of view of the optical lens; f is the effective focal length of the optical lens.

9. The optical lens according to any one of claims 1 to 4, characterized in that, The optical lens satisfies: 6.5≤ObjH / ImgH≤8; ObjH is the object height corresponding to half of the maximum field of view of the optical lens; ImgH is the image height corresponding to half of the maximum field of view of the optical lens.

10. The optical lens according to any one of claims 1 to 4, characterized in that, The optical lens satisfies: 2≤(CT1+CT2+CT3) / f≤3.5; CT1 is the thickness of the first lens on the optical axis; CT2 is the thickness of the second lens along the optical axis; CT3 is the thickness of the third lens on the optical axis.

11. The optical lens according to any one of claims 1 to 4, characterized in that, The optical lens satisfies: 5≤(f2+f3) / f≤6; f2 is the effective focal length of the second lens; f3 is the effective focal length of the third lens; f is the effective focal length of the optical lens.

12. The optical lens according to any one of claims 1 to 4, characterized in that, The optical lens satisfies the following condition: f / EPD≤1.8; f is the effective focal length of the optical lens; EPD is the entrance pupil diameter of the optical lens.

13. The optical lens according to any one of claims 1 to 4, characterized in that, BFL / TTL≤0.3; BFL is the distance from the image-side surface of the third lens to the imaging surface on the optical axis; TTL is the distance from the object surface of the first lens to the imaging surface on the optical axis.

14. The optical lens according to any one of claims 1 to 4, characterized in that, The optical lens satisfies the following conditions: 1.5≤ND1≤1.6, 20≤VD1≤70; Wherein, ND1 is the refractive index of the first lens, and VD1 is the Abbe number of the first lens.

15. The optical lens according to any one of claims 1 to 4, characterized in that, The optical lens satisfies: 1.5≤ND2≤1.6, 20≤VD2≤70; Wherein, ND2 is the refractive index of the second lens, and VD2 is the Abbe number of the second lens.

16. The optical lens according to any one of claims 1 to 4, characterized in that, The optical lens satisfies the following conditions: 1.5≤ND3≤1.6, 20≤VD3≤70; Wherein, ND3 is the refractive index of the second lens, and VD3 is the Abbe number of the second lens.

17. An optical fingerprint module, characterized in that, The device includes an image sensor and an optical lens according to any one of claims 1 to 16, wherein the image sensor is disposed on the image side of the optical lens and forms the imaging surface.

18. An electronic device, characterized in that, The device includes a display screen and the optical fingerprint module of claim 17, wherein the display screen is disposed on the object side of the optical fingerprint module.

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