Optical lens

Abstract

The application discloses an optical lens, which comprises, in sequence from an object plane to an imaging plane along an optical axis, a flat glass without optical power, a first lens with negative optical power, the object side of which is a concave surface at a near optical axis, and the image side is a concave surface, a diaphragm, a second lens with positive optical power, the object side of which is a convex surface, and the image side is a convex surface, a third lens with negative optical power, the object side of which is a concave surface, and the image side is a convex surface, and a flat glass without optical power. The optical lens of the application adopts two plastic aspheric lenses and one glass aspheric lens, and has the advantages of super large field of view, small volume and small distortion, and can work in a relatively harsh environment such as a car.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of imaging lens, in particular to an optical lens. BACKGROUND

[0002] At present, the fingerprint recognition function is widely applied to various electronic devices such as mobile phones, computers and the like, and the fingerprint recognition has become an important configuration. Among them, the optical under-screen fingerprint technology develops fast, has good anti-interference and stability, and the cost can be reasonably controlled, so the optical under-screen fingerprint recognition technology is the most widely used fingerprint recognition method at present. However, the optical lens for the under-screen fingerprint recognition applied to the electronic device is small in size and accurate in recognition, but it is difficult to work stably and accurately in a relatively more severe environment such as a car. SUMMARY

[0003] Therefore, the purpose of the present application is to provide an optical lens which can work in a relatively more severe environment such as a car, and has at least the advantages of super large field of view angle, small size and small distortion.

[0004] The present application provides an optical lens, which comprises, in order from the object side to the imaging surface along the optical axis: a flat glass; a first lens with negative focal power, the object side surface of which is concave near the optical axis and the image side surface of which is concave; a diaphragm; a second lens with positive focal power, the object side surface of which is convex and the image side surface of which is convex; a third lens with negative focal power, the object side surface of which is concave and the image side surface of which is convex; and a filter; wherein the optical lens satisfies the following conditional expressions: 3<CT1 / CT12<4; 0.55<CT3 / CT2<0.75; wherein CT1 represents the center thickness of the first lens, CT12 represents the air gap of the first lens and the second lens on the optical axis, CT3 represents the center thickness of the third lens, and CT2 represents the center thickness of the second lens.

[0005] Compared with the prior art, the optical lens provided by the present application reasonably allocates the thickness and focal power of the three lenses, and reasonably controls the surface shape of each lens, so that the optical lens has the characteristics of super large field of view angle, small size and small distortion, and better meets the use requirements in a relatively severe environment. BRIEF DESCRIPTION OF DRAWINGS

[0006] Figure 1 The structure schematic diagram of the optical lens provided by the first embodiment of the present application is shown in the figure;

[0007] Figure 2 The field curvature curve of the optical lens in the first embodiment of the present application is shown in the figure;

[0008] Figure 3 The optical distortion curve of the optical lens in the first embodiment of the present application is shown in the figure;

[0009] Figure 4 A relative illumination curve of the optical lens in the first embodiment of the present application;

[0010] Figure 5 A structural schematic diagram of the optical lens provided in the second embodiment of the present application;

[0011] Figure 6 A field curvature curve of the optical lens in the second embodiment of the present application;

[0012] Figure 7 An optical distortion curve of the optical lens in the second embodiment of the present application;

[0013] Figure 8 A relative illumination curve of the optical lens in the second embodiment of the present application;

[0014] Figure 9 A structural schematic diagram of the optical lens provided in the third embodiment of the present application;

[0015] Figure 10 A field curvature curve of the optical lens in the third embodiment of the present application;

[0016] Figure 11 An optical distortion curve of the optical lens in the third embodiment of the present application;

[0017] Figure 12 A relative illumination curve of the optical lens in the third embodiment of the present application;

[0018] Figure 13 A structural schematic diagram of the optical lens provided in the fourth embodiment of the present application;

[0019] Figure 14 A field curvature curve of the optical lens in the fourth embodiment of the present application;

[0020] Figure 15 An optical distortion curve of the optical lens in the fourth embodiment of the present application;

[0021] Figure 16 A relative illumination curve of the optical lens in the fourth embodiment of the present application. DETAILED DESCRIPTION

[0022] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings show several embodiments of the present application. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used in the description herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0024] The present application provides an optical lens, comprising, along the optical axis from the object side to the imaging surface, a flat glass, a first lens, a diaphragm, a second lens, a third lens and a filter.

[0025] The first lens has negative optical power, the object side surface of the first lens is concave near the optical axis, and the image side surface of the first lens is concave; the second lens has positive optical power, the object side surface of the second lens is convex, and the image side surface of the second lens is convex; the third lens has negative optical power, the object side surface of the third lens is concave, and the image side surface of the third lens is convex; and the first lens, the second lens and the third lens are all aspherical lenses.

[0026] In some embodiments, the optical lens satisfies the following conditional expressions:

[0027] 3 < CT1 / CT12 < 4; (1)

[0028] 0.55 < CT3 / CT2 < 0.75; (2)

[0029] CT1 represents the center thickness of the first lens, CT12 represents the air gap of the first lens and the second lens on the optical axis, CT3 represents the center thickness of the third lens, and CT2 represents the center thickness of the second lens. By using a combination of three aspherical lenses, through specific surface shape matching and reasonable optical power distribution, while satisfying the above conditional expressions (1) and (2), the values of CT1 / CT12 and CT3 / CT2 are reasonably distributed, so that the optical lens has the characteristics of super large field of view (FOV > 130°), small volume (TTL < 2.65 mm) and small distortion (optical distortion is within 1.5%).

[0030] In some embodiments, the optical lens satisfies the following conditional expressions:

[0031] -2.0 < R11 / R12 < -1.2; (3)

[0032] 0.2 < CT1 / TTL < 0.3; (4)

[0033] R11 / R12>0.5; (3) -4

[0034] In some embodiments, the optical lens satisfies the following conditional expression:

[0035] -8

[0036] -2.5

[0037] wherein R21 represents a curvature radius of the object side surface of the second lens, R22 represents a curvature radius of the image side surface of the second lens, SAG22 represents a sag of the image side surface of the second lens, and SAG12 represents a sag of the image side surface of the first lens. By simultaneously satisfying the conditional expressions (5) and (6) above, the surface shape of the second lens is reasonably distributed, which is conducive to converging light, reducing the total length of the optical lens, and realizing miniaturization of the optical lens.

[0038] In some embodiments, the optical lens satisfies the following conditional expression:

[0039] 0.4

[0040] 0.6

[0041] wherein R31 represents a curvature radius of the object side surface of the third lens, R32 represents a curvature radius of the image side surface of the third lens, SAG31 represents a sag of the object side surface of the third lens, and SAG32 represents a sag of the image side surface of the third lens. By simultaneously satisfying the conditional expressions (7) and (8) above, the surface shape of the third lens is reasonably distributed, which is conducive to correcting the spherical aberration and the coma of each field of view, respectively, and improving the resolving power of the optical lens.

[0042] In some embodiments, the optical lens satisfies the following conditional expression:

[0043] 2

[0044] wherein φ32 represents the power of the image side surface of the third lens, and CT3 represents the center thickness of the third lens. The condition formula (9) is satisfied, and by reasonably distributing the relationship between the power of the image side surface of the third lens and the center thickness of the third lens, the mold forming of the third lens is facilitated, the processing tolerance of the third lens is reduced, and the yield of the product is improved.

[0045] In some embodiments, the optical lens satisfies the following condition formula:

[0046] 0.12 < (CT12+CT23) / (CT1+CT2+CT3) < 0.16; (10)

[0047] wherein CT12 represents the air separation of the first lens and the second lens on the optical axis, CT23 represents the air separation of the second lens and the third lens on the optical axis, CT1 represents the center thickness of the first lens, CT2 represents the center thickness of the second lens, and CT3 represents the center thickness of the third lens. The condition formula (10) is satisfied, and by reasonably distributing the relationship between the air separation of each lens on the optical axis and the center thickness of each lens, the distribution of each lens is made more compact, the total length of the optical lens is reduced, and the miniaturization of the optical lens is realized.

[0048] In some embodiments, the optical lens satisfies the following condition formula:

[0049] -15 < (SAG22+SAG31) / CT23 < -6; (11)

[0050] wherein SAG22 represents the sag of the image side surface of the second lens, SAG31 represents the sag of the object side surface of the third lens, and CT23 represents the air separation of the second lens and the third lens on the optical axis. The condition formula (11) is satisfied, and by reasonably distributing the relationship between the edge air gap of the second lens and the third lens and the air separation on the optical axis, the distortion of the peripheral field of view is corrected.

[0051] In some embodiments, the optical lens satisfies the following condition formula:

[0052] -0.25 < (R31-R32) / (R11-R12) < -0.07; (12)

[0053] wherein R31 represents the radius of curvature of the object side surface of the third lens, R32 represents the radius of curvature of the image side surface of the third lens, R11 represents the radius of curvature of the object side surface of the first lens, and R12 represents the radius of curvature of the image side surface of the first lens. The condition formula (12) is satisfied, and by reasonably distributing the relationship between the radius of curvature of the third lens and the first lens, the focal length of the optical lens is increased, and the image height of the optical lens is increased.

[0054] In some embodiments, the optical lens satisfies the following conditional expression:

[0055] 0.28 < FFL / TTL < 0.35; (13)

[0056] Wherein, FFL represents the distance from the third lens image side surface to the imaging surface on the optical axis, and TTL represents the distance from the first lens object side surface to the imaging surface on the optical axis. By reasonably controlling the proportion of the optical back focus in the total optical length, the risk of interference between the mechanism and the lens is reduced, and the mechanism design of the product is facilitated.

[0057] In some embodiments, the third lens is a glass aspheric lens. The third lens is selected from glass materials, which is conducive to reducing the influence of different temperatures on the performance of the optical lens, and is conducive to use in relatively harsh environments.

[0058] In some embodiments, the optical lens satisfies the following conditional expression:

[0059] 0.9 < Nd3 / Nd2 < 1.0; (14)

[0060] Wherein, Nd3 represents the refractive index of the third lens, and Nd2 represents the refractive index of the second lens. By reasonably controlling the relationship between the refractive indices of the second lens and the third lens, a glass material with a smaller refractive index can be selected, thereby reducing the production cost of the optical lens.

[0061] In various embodiments of the present application, when the lens adopts an aspheric lens, the surface shape of the aspheric lens satisfies the following equation:

[0062]

[0063] Wherein, z is the distance from the vertex of the aspheric surface when the aspheric surface is at a height of h along the optical axis, c is the near-axis curvature of the surface, k is the conic coefficient, A 2i is the aspheric surface form coefficient of the 2i-th order.

[0064] The present application will be further described in the following embodiments. In various embodiments, the thickness, radius of curvature, and material selection of each lens in the optical lens are different, and the specific differences can be referred to the parameter table of each embodiment. The following embodiments are only preferred embodiments of the present application, but the embodiments of the present application are not limited to the following embodiments, and any changes, substitutions, combinations or simplifications made without departing from the innovative points of the present application should be regarded as equivalent replacement methods, and are included in the protection scope of the present application.

[0065] First embodiment

[0066] Referring to Figure 1 , a structural diagram of an optical lens 100 provided in a first embodiment of the present application is shown, the optical lens 100 comprising, in order from an object side to an imaging surface S11 along an optical axis, a flat glass G1, a first lens L1, a stop ST, a second lens L2, a third lens L3, and a filter G2.

[0067] Specifically, the object side surface of the flat glass G1 is S1, and the image side surface is S2; the first lens L1 has a negative focal power, the object side surface S3 of the first lens is concave at the near optical axis, and the image side surface S4 of the first lens is concave; the second lens L2 has a positive focal power, the object side surface S5 of the second lens is convex, and the image side surface S6 of the second lens is convex; the third lens L3 has a negative focal power, the object side surface S7 of the third lens is concave, and the image side surface S8 of the third lens is convex; the object side surface of the filter G2 is S9, and the image side surface is S10. Among them, the first lens L1 and the second lens L2 are plastic aspheric lenses, and the third lens L3 is a molded aspheric lens.

[0068] The related parameters of each lens in the optical lens 100 provided in the first embodiment of the present application are shown in Table 1.

[0069] Table 1

[0070]

[0071]

[0072] The face type coefficients of each aspheric surface of the optical lens 100 in the present embodiment are shown in Table 2.

[0073] Table 2

[0074]

[0075] In the present embodiment, the structural diagram, the field curvature, the optical distortion, and the relative luminance curve of the optical lens 100 are shown in Figure 1 , Figure 2 , Figure 3 and Figure 4 respectively.

[0076] Figure 2 The field curvature curve of the optical lens 100 in the present embodiment is shown, which represents the field curvature values at different fields of view. It can be seen from the figure that the field curvature values at each field of view are controlled within ±0.1 mm, indicating that the field curvature of each field of view of the optical lens 100 is well corrected.

[0077] Figure 3The optical distortion curve of the optical lens 100 in the embodiment is shown, which represents the distortion at different fields of view on the imaging plane. It can be seen from the figure that the optical distortion is controlled within ±1.5%, which shows that the distortion of the optical lens 100 is well corrected.

[0078] Figure 4 The relative illumination curve of the optical lens 100 in the embodiment is shown, which represents the ratio of the illumination at different fields of view to the illumination at the central field of view. It can be seen from the figure that the relative illumination of the maximum field of view is controlled to be more than 35%, which shows that the relative illumination of each field of view of the optical lens 100 is good.

[0079] Second Embodiment

[0080] Referring to Figure 5 , a structural schematic diagram of an optical lens 200 provided in the second embodiment of the present application is shown. The optical lens 200 in the embodiment is basically the same as that in the first embodiment, and the differences are shown in Table 3 and Table 4.

[0081] The related parameters of each lens in the optical lens 200 provided in the second embodiment of the present application are shown in Table 3.

[0082] Table 3

[0083]

[0084]

[0085] The aspheric surface type coefficients of the optical lens 200 in the embodiment are shown in Table 4.

[0086] Table 4

[0087]

[0088] In the embodiment, the structural diagram, the field curvature, the optical distortion and the relative illumination curve of the optical lens 200 are shown in Figure 5 , Figure 6 , Figure 7 and Figure 8 respectively. It can be seen from the figures that the field curvature is controlled within ±0.2mm, which shows that the field curvature of the optical lens 200 is well corrected; the optical distortion is controlled within ±1.5%, which shows that the distortion of the optical lens 200 is well corrected; the relative illumination of the maximum field of view is controlled to be more than 35%, which shows that the relative illumination of each field of view of the optical lens 200 is good.

[0089] Third Embodiment

[0090] Referring to Figure 9, shown is a structural schematic view of the optical lens 300 provided in the second embodiment of the present application, the optical lens 300 in the embodiment is basically same as the first embodiment, and the difference is shown in Table 5 and Table 6.

[0091] The related parameters of each lens in the optical lens 300 provided in the third embodiment of the present application are shown in Table 5.

[0092] Table 5

[0093]

[0094] The surface type coefficients of each aspheric surface of the optical lens 300 in the embodiment are shown in Table 6.

[0095] Table 6

[0096]

[0097] In the embodiment, the structural diagram, the field curvature, the optical distortion and the relative luminance curve of the optical lens 300 are shown in Figure 9 、 Figure 10 、 Figure 11 and Figure 12 respectively. It can be seen from the figures that the field curvature is controlled within ±0.1 mm, which indicates that the field curvature of the optical lens 300 is well corrected; the optical distortion is controlled within ±1.5%, which indicates that the distortion of the optical lens 300 is well corrected; the relative luminance of the maximum field of view is controlled to be more than 30%, which indicates that the relative luminance of each field of view of the optical lens 300 is good.

[0098] Fourth Embodiment

[0099] Please refer to Figure 13 , shown is a structural schematic view of the optical lens 400 provided in the second embodiment of the present application, the optical lens 400 in the embodiment is basically same as the first embodiment, and the difference is shown in Table 7 and Table 8.

[0100] The related parameters of each lens in the optical lens 400 provided in the third embodiment of the present application are shown in Table 7.

[0101] Table 7

[0102]

[0103] The surface type coefficients of each aspheric surface of the optical lens 400 in the embodiment are shown in Table 8.

[0104] Table 8

[0105]

[0106] In the embodiment, the structural diagram, the field curvature, the optical distortion and the relative illumination curve of the optical lens 400 are shown in Figures Figure 13 、 Figure 14 、 Figure 15 and Figure 16 respectively. As can be seen from the figures, the field curvature is controlled within ±0.1 mm, which indicates that the field curvature of the optical lens 400 is well corrected; the optical distortion is controlled within ±1.5%, which indicates that the distortion of the optical lens 400 is well corrected; and the relative illumination of the maximum field of view is controlled to be more than 30%, which indicates that the relative illumination of each field of view of the optical lens 400 is good.

[0107] Table 9 is the optical characteristics corresponding to the above four embodiments, mainly including the effective focal length f, the aperture number F# of the system, the total optical length TTL, the object height OH, the maximum field of view FOV and the image height IH corresponding to the object height OH, and the numerical value corresponding to each of the above condition formulas.

[0108] Table 9

[0109]

[0110] In summary, the optical lens provided by the present application adopts three aspheric lenses with specific optical powers, and through specific surface shape matching and reasonable optical power distribution, the FOV of the optical lens reaches more than 130°, the object height reaches 9.62 mm, and the fingerprint recognition range is wide; at the same time, the three lenses are arranged compactly, the total length of the optical lens is reduced, and the optical lens has the advantages of super large field of view, small volume and small distortion.

[0111] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0112] The above-described embodiments only express several implementation manners of the present application, the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the present application. It should be noted that, for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. An optical lens characterized in that, In order from the object side to the imaging surface along the optical axis, the optical lens comprises, in sequence: a flat glass, a first lens, a diaphragm, a second lens, a third lens, and a filter; The first lens has negative refractive power, the object side surface of the first lens is concave at the near optical axis, and the image side surface of the first lens is concave; The second lens has positive refractive power, the object side surface of the second lens is convex, and the image side surface of the second lens is convex; The third lens has negative refractive power, the object side surface of the third lens is concave, and the image side surface of the third lens is convex; The optical lens satisfies the following conditional expression: 3 < CT1 / CT12 < 4; 0.55 < CT3 / CT2 < 0.75; Wherein, CT1 represents the center thickness of the first lens, CT12 represents the air gap of the first lens and the second lens on the optical axis, CT3 represents the center thickness of the third lens, and CT2 represents the center thickness of the second lens.

2. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: -2.0 < R11 / R12 < -1.2; 0.2 < CT1 / TTL < 0.3; Wherein, R11 represents the curvature radius of the object side surface of the first lens, R12 represents the curvature radius of the image side surface of the first lens, CT1 represents the center thickness of the first lens, and TTL represents the distance from the object side surface of the first lens to the imaging surface on the optical axis.

3. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: -8 < R21 / R22 < -4; -2.5 < SAG22 / SAG12 < -1.5; Wherein, R21 represents the curvature radius of the object side surface of the second lens, R22 represents the curvature radius of the image side surface of the second lens, SAG22 represents the sag of the image side surface of the second lens, and SAG12 represents the sag of the image side surface of the first lens.

4. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: 0.4 < R31 / R32 < 0.6; 0.6 < SAG31 / SAG32 < 0.8; Wherein, R31 represents the curvature radius of the object side surface of the third lens, R32 represents the curvature radius of the image side surface of the third lens, SAG31 represents the sag of the object side surface of the third lens, and SAG32 represents the sag of the image side surface of the third lens.

5. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: 2 < φ32 / CT3 < 4; Wherein, φ32 represents the refractive power of the image side surface of the third lens, and CT3 represents the center thickness of the third lens.

6. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: 0.12 < (CT12+CT23) / (CT1+CT2+CT3) < 0.16; Wherein, CT12 represents the air gap of the first lens and the second lens on the optical axis, CT23 represents the air gap of the second lens and the third lens on the optical axis, CT1 represents the center thickness of the first lens, CT2 represents the center thickness of the second lens, and CT3 represents the center thickness of the third lens.

7. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: -15 < (SAG22+SAG31) / CT23 < -6; Wherein, SAG22 represents the sag of the second lens image side surface, SAG31 represents the sag of the third lens object side surface, CT23 represents the air interval of the second lens and the third lens on the optical axis.

8. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: -0.25 < (R31-R32) / (R11-R12) < -0.07; Wherein, R31 represents the radius of curvature of the third lens object side surface, R32 represents the radius of curvature of the third lens image side surface, R11 represents the radius of curvature of the first lens object side surface, R12 represents the radius of curvature of the first lens image side surface.

9. The optical lens of claim 1, wherein, The optical lens satisfies the following conditional expression: 0.28 < FFL / TTL < 0.35; Wherein, FFL represents the distance from the third lens image side surface to the imaging surface on the optical axis, TTL represents the distance from the first lens object side surface to the imaging surface on the optical axis.

10. The optical lens of claim 1, wherein, The third lens is a glass aspheric lens.

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