Imaging lens

Abstract

An imaging lens includes, in order from the object side to the image side along the optical axis, a first lens group, a second lens group, a third lens group, and a fourth lens group. The first lens group has positive refractive power. The second lens group has negative refractive power, and includes at least two lenses with negative refractive power. The third lens group has positive refractive power, and includes a 3-1 lens with positive refractive power, a 3-2 lens, and a 3-3 lens with a concave surface facing the object side. The fourth lens group has positive refractive power. The 3-1 lens, the 3-2 lens, and the 3-3 lens are arranged in order from the object side to the image side along the optical axis, and are adjacent to each other.

Description

Technical Field

[0001] This invention relates to an imaging lens. Background Technology

[0002] Most existing surveillance cameras do not have zoom capabilities. However, with the development of industrial automation and the Internet of Things, people have increasingly higher requirements for surveillance cameras, especially for miniaturization, high resolution, low cost, and high zoom ratio. Existing imaging lenses can no longer meet the requirements of today's surveillance cameras. A new imaging lens architecture is needed to simultaneously meet the requirements of miniaturization, high resolution, low cost, and high zoom ratio to satisfy the needs of surveillance cameras. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide an imaging lens that has a short total length, high resolution, low cost and high zoom ratio, but still has good optical performance.

[0004] The technical solution adopted by this invention to solve its technical problem is to provide an imaging lens comprising a first lens group, a second lens group, a third lens group, and a fourth lens group. The first lens group has positive refractive power. The second lens group has negative refractive power, and this second lens group includes at least two negative refractive power lenses. The third lens group has positive refractive power, and this third lens group includes a 3-1 lens, a 3-2 lens, and a 3-3 lens. The 3-1 lens has positive refractive power, and the 3-3 lens includes a concave surface facing the object side. The fourth lens group has positive refractive power. The first lens group, the second lens group, the third lens group, and the fourth lens group are arranged sequentially along the optical axis from the object side to the image side. The 3-1 lens, the 3-2 lens, and the 3-3 lens are arranged sequentially along the optical axis from the object side to the image side, and these lenses are adjacent to each other. When the imaging lens of this invention satisfies the above features and no other additional features or conditions are required, the basic function of the imaging lens of this invention can be achieved.

[0005] The first lens group includes lens 1-1 and lens 1-2. Lens 1-1 is a biconvex lens with positive refractive power, and includes one convex surface facing the object side and another convex surface facing the image side. Lens 1-2 also has positive refractive power and includes one convex surface facing the object side. The second lens group includes lens 2-1 and lens 2-2. Lens 2-1 has negative refractive power and includes one concave surface facing the image side. Lens 2-2 also has negative refractive power and includes one concave surface facing the object side. The third lens group may further include lens 3-4 disposed between lens 3-3 and the fourth lens group. Lens 3-1 is a biconvex lens, and includes one convex surface facing the object side and another convex surface facing the image side. Lens 3-2 has positive refractive power and includes one convex surface facing the object side. Lens 3-3 is a biconcave lens with negative refractive power and may further include another concave surface facing the image side. Lens 3-4 is a meniscus lens with negative refractive power and includes one convex surface facing the object side and one concave surface facing the image side. The fourth lens group includes lens 4-1, which has positive refractive power and includes a convex surface facing the object side. Lenses 1-1 and 1-2 are arranged sequentially along the optical axis from the object side to the image side. Lenses 2-1 and 2-2 are arranged sequentially along the optical axis from the object side to the image side.

[0006] The fourth lens group may further include lens 4-2 disposed between the third lens group and lens 4-1, wherein lens 1-2 is a meniscus lens and may further include a concave surface facing the image side. Lens 2-1 is a meniscus lens and may further include a convex surface facing the object side. Lens 2-2 is a meniscus lens and may further include a convex surface facing the image side. Lens 3-2 is a meniscus lens and may further include a concave surface facing the image side. Lens 4-1 is a biconvex lens and may further include another convex surface facing the image side. Lens 4-2, being a meniscus lens, has negative refractive power and includes a concave surface facing the object side and a convex surface facing the image side.

[0007] The first lens group may further include lenses 1-3 disposed between the object side and lens 1-1, wherein lens 3-2 is a biconvex lens and may further include another convex surface facing the image side. Lens 4-1 is a meniscus lens and may further include a concave surface facing the image side. Lens 1-3 is a meniscus lens with negative refractive power and includes a convex surface facing the object side and a concave surface facing the image side.

[0008] Lens 1-2 is a biconvex lens and may further include another convex surface facing the image side. Lens 2-1 is a biconcave lens and may further include another concave surface facing the object side. Lens 2-2 is a biconcave lens and may further include another concave surface facing the image side.

[0009] The second lens group may further include lens 2-3 disposed between lens 2-2 and the third lens group, wherein lens 1-2 is a meniscus lens and may further include a concave surface facing the image side. Lens 2-1 is a meniscus lens and may further include a convex surface facing the object side. Lens 2-2 is a meniscus lens and may further include a convex surface facing the image side. Lens 2-3 is a meniscus lens with positive refractive power and includes a convex surface facing the object side and a concave surface facing the image side.

[0010] The third lens group may further include an aperture positioned between the second lens group and the 3-1 lens.

[0011] The spacing between these lens groups can be changed along the optical axis to allow the imaging lens to zoom from the wide-angle end to the middle end and then to the telephoto end to change the focal length. The fourth lens group can move along the optical axis for focusing.

[0012] The imaging lens must satisfy at least one of the following conditions: -0.34 degrees / mm ≤ FOV / f1 ≤ 0.49 degrees / mm; -0.36 ≤ fG1 / f1 ≤ 0.68; -0.13 ≤ fG2 / fG23 ≤ 0.55; 18 ≤ TTL / TG34 ≤ 74; where FOV is the maximum field of view of the imaging lens, f1 is the effective focal length of the lens closest to the object side, fG1 is the effective focal length of the first lens group, fG2 is the effective focal length of the second lens group, fG23 is the effective focal length of the lens closest to the image side in the second lens group, TTL is the distance along the optical axis from the object side of the lens closest to the object side in the first lens group to the imaging plane, and TG34 is the thickness along the optical axis of the lens closest to the image side in the third lens group.

[0013] The imaging lens must satisfy at least one of the following conditions: 90≤VdG1+VdG3≤107; -3.9≤(L1R1×L1R2) / (L2R1×L2R2)≤-0.05; 65≤VdG31+VdG34≤100; where VdG1 is the average Abbe coefficient of all lenses in the first lens group, VdG3 is the average Abbe coefficient of all lenses in the third lens group, L1R1 is the radius of curvature of the object side of the lens closest to the object side, L1R2 is the radius of curvature of the image side of the lens closest to the object side, L2R1 is the radius of curvature of the object side of the second lens closest to the object side, L2R2 is the radius of curvature of the image side of the second lens closest to the object side, VdG31 is the Abbe coefficient of the lens closest to the object side in the third lens group, and VdG34 is the Abbe coefficient of the lens closest to the image side in the third lens group.

[0014] The imaging lens implementing the present invention has the following advantages: it has a shorter overall length, higher resolution, lower cost, and a higher zoom ratio, while still having good optical performance. Attached Figure Description

[0015] Figure 1A , 1B 1C is a schematic diagram of the lens configuration and optical path at the wide-angle end, the middle end and the telephoto end of the imaging lens according to the first embodiment of the present invention.

[0016] Figure 2A , 2B 2C represents the longitudinal aberration, field curvature, and distortion diagrams at the wide-angle end of the first embodiment of the imaging lens according to the present invention.

[0017] Figure 3A , 3B 3C refers to the longitudinal aberration map, field curvature map, and distortion map at the middle end of the first embodiment of the imaging lens according to the present invention.

[0018] Figure 4A , 4B 4C refers to the longitudinal aberration map, field curvature map, and distortion map at the telescope distance of the first embodiment of the imaging lens according to the present invention.

[0019] Figure 5A , 5B Figure 5C is a schematic diagram of the lens configuration and optical path at the wide-angle end, the middle end, and the telephoto end of the imaging lens according to the second embodiment of the present invention.

[0020] Figure 6A , 6B 6C is a longitudinal aberration diagram, field curvature diagram, and distortion diagram at the wide-angle end of a second embodiment of the imaging lens according to the present invention.

[0021] Figure 7A , 7B 7C is a longitudinal aberration map, field curvature map, and distortion map at the middle end of a second embodiment of the imaging lens according to the present invention.

[0022] Figure 8A , 8B 8C is a longitudinal aberration map, field curvature map, and distortion map at the telescope distance according to a second embodiment of the imaging lens of the present invention.

[0023] Figure 9A , 9B Figure 9C is a schematic diagram of the lens configuration and optical path at the wide-angle end, the middle end, and the telephoto end of the imaging lens according to the third embodiment of the present invention.

[0024] Figure 10A , 10B 10C is a longitudinal aberration diagram, field curvature diagram, and distortion diagram at the wide-angle end of the third embodiment of the imaging lens according to the present invention.

[0025] Figure 11A , 11B 11C is a longitudinal aberration map, field curvature map, and distortion map at the middle end of the third embodiment of the imaging lens according to the present invention.

[0026] Figure 12A , 12B 12C is a longitudinal aberration map, field curvature map, and distortion map at the telescope distance of a third embodiment of the imaging lens according to the present invention. Detailed Implementation

[0027] This invention provides an imaging lens, comprising: a first lens group having positive refractive power; a second lens group having negative refractive power, the second lens group including at least two lenses having negative refractive power; a third lens group having positive refractive power, the third lens group including a 3-1 lens, a 3-2 lens, and a 3-3 lens, the 3-1 lens having positive refractive power, and the 3-3 lens including a concave surface facing the object side; and a fourth lens group having positive refractive power; wherein the first lens group, the second lens group, the third lens group, and the fourth lens group are arranged sequentially along the optical axis from the object side to the image side; wherein the 3-1 lens, the 3-2 lens, and the 3-3 lens are arranged sequentially along the optical axis from the object side to the image side, and these lenses are adjacent to each other. When the imaging lens of this invention satisfies the above features, it is a preferred embodiment of this invention.

[0028] The imaging lens of this invention is a variable focal length lens. Its first lens group is fixed, while the second, third, and fourth lens groups can move along the optical axis to change the spacing between each lens group, allowing the imaging lens to zoom from a wide-angle end to a mid-range end and then to a telephoto end. In various embodiments of the imaging lens, the zoom ratio from the wide-angle end to the telephoto end is approximately 3x.

[0029] Please refer to Tables 1, 3 and 5 below, where Tables 1, 3 and 5 are parameter tables for each lens according to the first to third embodiments of the imaging lens of the present invention.

[0030] Figure 1A , 1B 1C is a schematic diagram of the lens configuration and optical path at the wide-angle end, the middle end, and the telephoto end according to the first embodiment of the imaging lens of the present invention. Figure 5A , 5B 5C is a schematic diagram of the lens configuration and optical path at the wide-angle end, the middle end, and the telephoto end according to the second embodiment of the imaging lens of the present invention. Figure 9A , 9BFigure 9C is a schematic diagram of the lens configuration and optical path at the wide-angle end, middle end, and telephoto end of the imaging lens according to the third embodiment of the present invention. The imaging lens 1 includes a first lens group LG11, a second lens group LG12, a third lens group LG13, and a fourth lens group LG14. The first lens group LG11 has positive refractive power and includes 1-3 lens L110, 1-1 lens L11, and 1-2 lens L12. The second lens group LG12 has negative refractive power and includes 2-1 lens L13, 2-2 lens L14, and 2-3 lens L111. The third lens group LG13 has positive refractive power and includes an aperture ST1, 3-1 lens L15, 3-2 lens L16, 3-3 lens L17, and 3-4 lens L18. The fourth lens group LG14 has positive refractive power and includes 4-1 lens L19. Imaging lens 2 includes a first lens group LG21, a second lens group LG22, a third lens group LG23, and a fourth lens group LG24. The first lens group LG21 has positive refractive power and includes a 1-1 lens L21 and a 1-2 lens L22. The second lens group LG22 has negative refractive power and includes a 2-1 lens L23 and a 2-2 lens L24. The third lens group LG23 has positive refractive power and includes an aperture ST2, a 3-1 lens L25, a 3-2 lens L26, a 3-3 lens L27, and a 3-4 lens L28. The fourth lens group LG24 has positive refractive power and includes a 4-2 lens L210 and a 4-1 lens L29. Imaging lens 3 includes a first lens group LG31, a second lens group LG32, a third lens group LG33, and a fourth lens group LG34. The first lens group LG31 has positive refractive power and includes a 1-3 lens L310, a 1-1 lens L31, and a 1-2 lens L32. The second lens group LG32 has negative refractive power and includes a 2-1 lens L33 and a 2-2 lens L34. The third lens group LG33 has positive refractive power and includes an aperture ST3, a 3-1 lens L35, a 3-2 lens L36, a 3-3 lens L37, and a 3-4 lens L38. The fourth lens group LG34 has positive refractive power and includes a 4-1 lens L39.

[0031] Lenses 1-1, L11, L21, and L31, are biconvex lenses with positive refractive power, made of glass. Their object-side surfaces S13, S21, and S33 are convex, and their image-side surfaces S14, S22, and S34 are convex. Both object-side surfaces S13, S21, and S33 and image-side surfaces S14, S22, and S34 are spherical surfaces. Lenses 1-2, L12, L22, and L32, also have positive refractive power, made of glass. Their object-side surfaces S15, S23, and S35 are convex, and both object-side surfaces S15, S23, and S35 and image-side surfaces S16, S24, and S36 are spherical surfaces. Lenses 2-1 L13, L23, and L33 have negative refractive power and are made of glass. Their image-side surfaces S18, S26, and S38 are concave, while their object-side surfaces S17, S25, and S37, as well as their image-side surfaces S18, S26, and S38, are spherical surfaces. Lenses 2-2 L14, L24, and L34 have negative refractive power and are made of glass. Their object-side surfaces S19, S27, and S39 are concave, while their image-side surfaces S110, S28, and S310 are spherical surfaces. Lenses 3-1 L15, L25, and L35 are biconvex lenses with positive refractive power, made of glass. Their object-side surfaces S114, S210, and S312 are convex, as are their image-side surfaces S115, S211, and S313. Both object-side surfaces S114, S210, and S312 and image-side surfaces S115, S211, and S313 are spherical surfaces. Lenses 3-2 L16, L26, and L36 have positive refractive power, made of glass. Their object-side surfaces S116, S212, and S314 are convex, as are their image-side surfaces S117, S213, and S315. Lenses L17, L27, and L37 (3-3) are biconcave lenses with negative refractive power, made of glass. Their object-side surfaces S118, S214, and S316 are concave, and their image-side surfaces S119, S215, and S317 are concave. Both object-side surfaces S118, S214, and S316 and image-side surfaces S119, S215, and S317 are spherical surfaces. Lenses L18, L28, and L38 (3-4) are meniscus lenses with negative refractive power, also made of glass. Their object-side surfaces S120, S216, and S318 are convex, and their image-side surfaces S121, S217, and S319 are concave. Both object-side surfaces S120, S216, and S318 and image-side surfaces S121, S217, and S319 are spherical surfaces. Lenses L19, L29, and L39 of type 4-1 have positive refractive power and are made of glass. Their object-side surfaces S122, S220, and S320 are convex, while their image-side surfaces S123, S221, and S321 are spherical.

[0032] In addition, imaging lenses 1, 2, and 3 must satisfy at least one of the following conditions (1) to (7) for it to be a preferred embodiment of the present invention:

[0033] -0.34 degrees / mm ≤ FOV / f1 ≤ 0.49 degrees / mm; (1)

[0034] -0.36 ≤ fG1 / f1 ≤ 0.68; (2)

[0035] -0.13 ≤ fG2 / fG23 ≤ 0.55; (3)

[0036] 18 ≤ TTL / TG34 ≤ 74; (4)

[0037] 90 ≤ VdG1 + VdG3 ≤ 107; (5)

[0038] -3.9 ≤ (L1R1 × L1R2) / (L2R1 × L2R2) ≤ -0.05; (6)

[0039] 65 ≤ VdG31 + VdG34 ≤ 100; (7)

[0040] Wherein, FOV is the maximum field of view of imaging lenses 1, 2, and 3 in the first to third embodiments; f1 is the effective focal length of lenses L110, L21, and L310 closest to the object side in the first to third embodiments; fG2 is the effective focal length of the second lens group LG12, LG22, and LG32 in the first to third embodiments; fG23 is the effective focal length of lenses L111, L24, and L34 closest to the image side in the second lens group LG12, LG22, and LG32 in the first to third embodiments; and TTL is the effective focal length of the first lens group LG110 in the first to third embodiments. 1. The distance from the object-side surfaces S11, S21, S31 of the lenses L110, L21, L310 closest to the object side in LG21, LG31 to the imaging surfaces IMA1, IMA2, IMA3 along the optical axes OA1, OA2, OA3; TG34 is the thickness of the lenses L18, L28, L38 closest to the image side in the third lens group LG13, LG23, LG33 in the first to third embodiments along the optical axes OA1, OA2, OA3; VdG1 is the average Abbe coefficient of all lenses in the first lens group LG11, LG21, LG31 in the first to third embodiments. In the first to third embodiments, VdG3 represents the average Abbe coefficient of all lenses in the third lens group LG13, LG23, and LG33; L1R1 represents the radius of curvature of the object-side surfaces S11, S21, and S31 of the lenses L110, L21, and L310 closest to the object side in the first to third embodiments; L1R2 represents the radius of curvature of the image-side surfaces S12, S22, and S32 of the lenses L110, L21, and L310 closest to the object side in the first to third embodiments; and L2R1 represents the radius of curvature of the second lens L11, L22, and L310 closest to the object side in the first to third embodiments. The radii of curvature of the object-side surfaces S13, S23, and S33 of lens 1; L1R2 is the radius of curvature of the image-side surfaces S14, S24, and S34 of the second lens L11, L22, and L31 closest to the object side in the first to third embodiments; VdG31 is the Abbe coefficient of the lens L15, L25, and L35 closest to the object side in the third lens group LG13, LG23, and LG33 in the first to third embodiments; and VdG34 is the Abbe coefficient of the lens L18, L28, and L38 closest to the image side in the third lens group LG13, LG23, and LG33 in the first to third embodiments. This allows imaging lenses 1, 2, and 3 to effectively shorten the overall lens length, effectively improve resolution, effectively correct aberrations, and achieve optical zoom functionality.

[0041] When condition (1) is met: -0.34° / mm ≤ FOV / f1 ≤ 0.49° / mm, excessive refractive power of the lens closest to the object side can be avoided, which is beneficial for the manufacturing of the lens closest to the object side. When condition (2) is met: -0.36 ≤ fG1 / f1 ≤ 0.68, manufacturing sensitivity can be effectively reduced to improve image quality. When condition (3) is met: -0.13 ≤ fG2 / fG23 ≤ 0.55, the relative illumination of the imaging lens can be improved. When condition (4) is met: 18 ≤ TTL / TG34 ≤ 74, the total length of the imaging lens can be effectively shortened. When condition (5) is met: 90 ≤ VdG1 + VdG3 ≤ 107, chromatic aberration can be effectively reduced to improve image quality. When condition (6) is met: -3.9≤(L1R1×L1R2) / (L2R1×L2R2)≤-0.05, manufacturing sensitivity can be effectively reduced, which is beneficial to the production of imaging lenses. When condition (7) is met: 65≤VdG31+VdG34≤100, the chromatic aberration value of the imaging lens can be effectively reduced. When conditions (1), (5) and (7) are met simultaneously: -0.34 degrees / mm≤FOV / f1≤0.49 degrees / mm; 90≤VdG1+VdG3≤107; and 65≤VdG31+VdG34≤100, chromatic aberration can be effectively reduced and image quality can be improved.

[0042] The first embodiment of the imaging lens of the present invention will now be described in detail. Please refer to... Figure 1A , Figure 1B and Figure 1C The imaging lens 1 includes a first lens group LG11, a second lens group LG12, a third lens group LG13, a fourth lens group LG14, a filter OF1, and a protective glass CG1. The first lens group LG11, the second lens group LG12, the third lens group LG13, the fourth lens group LG14, the filter OF1, and the protective glass CG1 are arranged sequentially along the optical axis OA1 from the object side to the image side. The first lens group LG11 includes a 1-3 lens L110, a 1-1 lens L11, and a 1-2 lens L12, which are arranged sequentially along the optical axis OA1 from the object side to the image side. The second lens group LG12 includes a 2-1 lens L13, a 2-2 lens L14, and a 2-3 lens L111, which are arranged sequentially along the optical axis OA1 from the object side to the image side. The third lens group LG13 includes an aperture ST1, a 3-1 lens L15, a 3-2 lens L16, a 3-3 lens L17, and a 3-4 lens L18, arranged sequentially from the object side to the image side along the optical axis OA1. The fourth lens group LG14 includes a 4-1 lens L19. During imaging, light rays from the object side are finally imaged onto the imaging plane IMA1.

[0043] Imaging lens 1 consists of a wide-angle end (such as...) Figure 1A Zoom to the middle (as shown) Figure 1B (As shown) Zoom in again to the telephoto end (e.g.) Figure 1C As shown, the first lens group LG11 is fixed, the second lens group LG12 moves along the optical axis OA1 towards the image side, the third lens group LG13 moves along the optical axis OA1 towards the object side, and the fourth lens group LG14 moves along the optical axis OA1 towards the image side. This results in the distance between the first lens group LG11 and the second lens group LG12 increasing, the distance between the second lens group LG12 and the third lens group LG13 decreasing, and the distance between the third lens group LG13 and the fourth lens group LG14 increasing. The aforementioned distances change as the imaging lens 1 zooms from the wide-angle end to the middle end and then to the telephoto end. This can be explained by... Figure 1A , Figure 1B and Figure 1C It is clearly visible in the image. The imaging lens 1 of the first embodiment consists of a wide-angle end (such as...) Figure 1A (As shown) Zoom to remote distance (e.g.) Figure 1C When shown), its zoom ratio is approximately 3x (71.95221mm / 24.04484mm≈2.99). The fourth lens group LG14 can move along the optical axis OA1 to enable the imaging lens 1 to focus. According to paragraphs 1 to 5 of the [Specific Implementation], wherein: lens 1-3 L110 is a meniscus lens with negative refractive power, made of glass, its object side S11 is convex, and its image side S12 is concave, both object side S11 and image side S12 are spherical surfaces; lens 1-2 L12 is a meniscus lens, its image side S16 is concave; lens 2-1 L13 is a meniscus lens, its object side S17 is convex; lens 2-2 L14 is a meniscus lens, its image side S110 is concave; lens 2-3 L111 is a meniscus lens with positive refractive power, made of glass, its object side S111 is convex, and its image side S110 is concave. 12 is concave, and both the object side S111 and the image side S112 are spherical surfaces; 3-2 lens L16 is a biconvex lens, and its image side S117 is convex; 4-1 lens L19 is a meniscus lens, and its image side S123 is concave; the object side S124 and the image side S125 of the filter OF1 are both planar; the object side S126 and the image side S127 of the protective glass CG1 are both planar; by utilizing the above-mentioned lens, aperture ST1 and the design that satisfies at least one of the conditions (1) to (7), the imaging lens 1 can effectively shorten the total length of the lens, effectively improve the resolution, effectively correct aberrations and realize the optical zoom function.

[0044] Table 1 is... Figure 1A , Figure 1B , Figure 1CTable of relevant parameters for each lens of the imaging lens 1 when it is at the wide-angle end, the middle end, and the telephoto end.

[0045] Table 1

[0046]

[0047]

[0048] Table 2 shows the relevant parameter values ​​of the imaging lens 1 in the first embodiment and the calculated values ​​of the corresponding conditions (1) to (7). As can be seen from Table 2, the imaging lens 1 in the first embodiment can meet the requirements of conditions (1) to (7).

[0049] Table 2

[0050]

[0051] Furthermore, the optical performance of the imaging lens 1 in the first embodiment also meets the requirements. Figure 2A It can be seen that, at the wide-angle end, the longitudinal aberration of the imaging lens 1 in the first embodiment is between -0.005mm and 0mm. Figure 2B It can be seen that the field curvature of the imaging lens 1 in the first embodiment is between -0.04mm and 0.01mm at the wide-angle end. Figure 2C It can be seen that the distortion of the imaging lens 1 in the first embodiment is between -2% and 0% at the wide-angle end. Figure 3A It can be seen that, in the first embodiment, the imaging lens 1 at the middle end has a longitudinal aberration between -0.005mm and 0.01mm. Figure 3B It can be seen that the field curvature of the imaging lens 1 in the first embodiment is between -0.02mm and 0.01mm at the middle end. Figure 3C It can be seen that the distortion of the imaging lens 1 in the first embodiment is between 0% and 2% at the middle end. Figure 4A It can be seen that the imaging lens 1 of the first embodiment, at the telescopic distance, has a longitudinal aberration between -0.025mm and -0.005mm. Figure 4B It can be seen that the field curvature of the imaging lens 1 in the first embodiment at the telescope is between -0.01mm and 0.02mm. Figure 4C It can be seen that the distortion of the imaging lens 1 in the first embodiment is between 0% and 2% at the telescope. It is evident that the longitudinal aberration, field curvature, and distortion of the imaging lens 1 in the first embodiment can be effectively corrected, thereby obtaining better optical performance.

[0052] The second embodiment of the imaging lens of the present invention will now be described in detail. Please refer to... Figure 5A , Figure 5B and Figure 5CThe imaging lens 2 includes a first lens group LG21, a second lens group LG22, a third lens group LG23, a fourth lens group LG24, a filter OF2, and a protective glass CG2. The first lens group LG21, the second lens group LG22, the third lens group LG23, the fourth lens group LG24, the filter OF2, and the protective glass CG2 are arranged sequentially along the optical axis OA2 from the object side to the image side. The first lens group LG21 includes a 1-1 lens L21 and a 1-2 lens L22, which are arranged sequentially along the optical axis OA2 from the object side to the image side. The second lens group LG22 includes a 2-1 lens L23 and a 2-2 lens L24, which are arranged sequentially along the optical axis OA2 from the object side to the image side. The third lens group LG23 includes aperture ST2, 3-1 lens L25, 3-2 lens L26, 3-3 lens L27, and 3-4 lens L28, arranged sequentially from the object side to the image side along the optical axis OA2. The fourth lens group LG24 includes 4-2 lens L210 and 4-1 lens L29, arranged sequentially from the object side to the image side along the optical axis OA2. During imaging, light rays from the object side are finally imaged onto the imaging plane IMA2.

[0053] Imaging lens 2 consists of a wide-angle end (such as...) Figure 5A Zoom to the middle (as shown) Figure 5B (As shown) Zoom in again to the telephoto end (e.g.) Figure 5C As shown, in this configuration, the first lens group LG21 remains fixed, the second lens group LG22 moves along the optical axis OA2 towards the image side, the third lens group LG23 moves along the optical axis OA2 towards the object side, and the fourth lens group LG24 moves along the optical axis OA2 towards the image side. This results in the distance between the first lens group LG21 and the second lens group LG22 increasing, the distance between the second lens group LG22 and the third lens group LG23 decreasing, and the distance between the third lens group LG23 and the fourth lens group LG24 increasing. The variation of these distances as the imaging lens 2 zooms from the wide-angle end to the intermediate end and then to the telephoto end can be explained by… Figure 5A , Figure 5B and Figure 5C It is clearly visible in the image. The imaging lens 2 of the second embodiment consists of a wide-angle end (such as...) Figure 5A (As shown) Zoom to remote distance (e.g.) Figure 5CWhen shown), its zoom ratio is approximately 3x (71.9346mm / 24.07183mm≈2.99). The fourth lens group LG24 can move along the optical axis OA2 to enable the imaging lens 2 to focus. According to paragraphs 1 to 5 of the [Specific Implementation], wherein: 1-2 lens L22 is a meniscus lens with its image-side surface S24 being concave; 2-1 lens L23 is a meniscus lens with its object-side surface S25 being convex; 2-2 lens L24 is a meniscus lens with its image-side surface S28 being convex; 3-2 lens L26 is a meniscus lens with its image-side surface S213 being concave; 4-2 lens L210 is a meniscus lens with negative refractive power, made of glass, with its object-side surface S218 being concave, its image-side surface S219 being convex, and its object-side surface S210 being concave. S218 and image side S219 are both spherical surfaces; 4-1 lens L29 is a biconvex lens, and its image side S221 is a convex surface; the filter OF2 has both its object side S222 and image side S223 as planes; the protective glass CG2 has both its object side S224 and image side S225 as planes; by utilizing the above-mentioned lens, aperture ST2 and the design that satisfies at least one of conditions (1) to (7), the imaging lens 2 can effectively shorten the total length of the lens, effectively improve the resolution, effectively correct aberrations and realize the optical zoom function.

[0054] Table 3 is... Figure 5A , Figure 5B , Figure 5C Table of relevant parameters for each lens of the imaging lens 2 when it is at the wide-angle end, the middle end, and the telephoto end.

[0055] Table 3

[0056]

[0057]

[0058] Table 4 shows the relevant parameter values ​​of the imaging lens 2 in the second embodiment and the calculated values ​​of the corresponding conditions (1) to (7). As can be seen from Table 4, the imaging lens 2 in the second embodiment can meet the requirements of conditions (1) to (7).

[0059] Table 4

[0060]

[0061] Furthermore, the optical performance of the imaging lens 2 in the second embodiment also meets the requirements. Figure 6A It can be seen that, at the wide-angle end, the longitudinal aberration of the imaging lens 2 in the second embodiment is between -0.005mm and 0.025mm. Figure 6B It can be seen that the field curvature of the imaging lens 2 in the second embodiment is between 0mm and 0.02mm at the wide-angle end. Figure 6CIt can be seen that the distortion of the imaging lens 2 in the second embodiment is between -1% and 0% at the wide-angle end. Figure 7A It can be seen that the imaging lens 2 in the second embodiment has a longitudinal aberration between -0.01mm and 0.015mm at the middle end. Figure 7B It can be seen that the field curvature of the imaging lens 2 in the second embodiment is between -0.01mm and 0.01mm at the middle end. Figure 7C It can be seen that the distortion of the imaging lens 2 in the second embodiment is between 0% and 1% at the middle end. Figure 8A It can be seen that the imaging lens 2 in the second embodiment, at the telescopic distance, has a longitudinal aberration between -0.015mm and 0.03mm. Figure 8B It can be seen that the field curvature of the imaging lens 2 in the second embodiment at the telescope is between -0.02mm and 0.01mm. Figure 8C It can be seen that the distortion of the imaging lens 2 in the second embodiment is between 0% and 1% at the telescope. It is evident that the longitudinal aberration, field curvature, and distortion of the imaging lens 2 in the second embodiment can be effectively corrected, thereby obtaining better optical performance.

[0062] The third embodiment of the imaging lens of the present invention will now be described in detail. Please refer to... Figure 9A , Figure 9B and Figure 9C Imaging lens 3 includes a first lens group LG31, a second lens group LG32, a third lens group LG33, a fourth lens group LG34, a filter OF3, and a protective glass CG3. The first lens group LG31, the second lens group LG32, the third lens group LG33, the fourth lens group LG34, the filter OF3, and the protective glass CG3 are arranged sequentially along the optical axis OA3 from the object side to the image side. The first lens group LG21 includes a 1-3 lens L310, a 1-1 lens L31, and a 1-2 lens L32, which are arranged sequentially along the optical axis OA3 from the object side to the image side. The second lens group LG32 includes a 2-1 lens L33 and a 2-2 lens L34, which are arranged sequentially along the optical axis OA3 from the object side to the image side. The third lens group LG33 includes an aperture ST3, a 3-1 lens L35, a 3-2 lens L36, a 3-3 lens L37, and a 3-4 lens L38, arranged sequentially from the object side to the image side along the optical axis OA3. The fourth lens group LG34 includes a 4-1 lens L39. During imaging, light rays from the object side are finally imaged onto the imaging plane IMA3.

[0063] Imaging lens 3 consists of a wide-angle end (such as...) Figure 9A Zoom to the middle (as shown) Figure 9B(As shown) Zoom in again to the telephoto end (e.g.) Figure 9C As shown, the first lens group LG31 remains fixed, the second lens group LG32 moves along the optical axis OA3 towards the image side, the third lens group LG33 moves along the optical axis OA3 towards the object side, and the fourth lens group LG34 moves along the optical axis OA3 towards the image side. This results in the distance between the first lens group LG31 and the second lens group LG32 increasing, the distance between the second lens group LG32 and the third lens group LG33 decreasing, and the distance between the third lens group LG33 and the fourth lens group LG34 increasing. The aforementioned distances change as the imaging lens 3 zooms from the wide-angle end to the middle end and then to the telephoto end. This can be explained by... Figure 9A , Figure 9B and Figure 9C It is clearly visible in the image. The imaging lens 3 of the third embodiment consists of a wide-angle end (such as...) Figure 9A (As shown) Zoom to remote distance (e.g.) Figure 9C When (as shown), its zoom ratio is approximately 3x (71.9813mm / 24.03277mm≈3.00). The fourth lens group LG34 can move along the optical axis OA3 to enable the imaging lens 3 to focus. According to paragraphs one to five of the [Specific Implementation], wherein: lens 1-3 L310 is a meniscus lens with negative refractive power, made of glass, with its object side S31 being convex and its image side S32 being concave, and both object side S31 and image side S32 being spherical surfaces; lens 1-2 L32 is a biconvex lens with its image side S36 being convex; lens 2-1 L33 is a biconcave lens with its object side S37 being concave; lens 2-2 L34 is a biconcave lens with its image side S310 being concave; lens 3-2 L36 is a biconvex lens. The lens has a convex image side surface S315; the 4-1 lens L39 is a meniscus lens with a concave image side surface S321; the filter OF3 has a flat object side surface S322 and an image side surface S323; the protective glass CG3 has a flat object side surface S324 and an image side surface S325; by utilizing the above-mentioned lens, aperture ST3 and the design that satisfies at least one of the conditions (1) to (7), the imaging lens 3 can effectively shorten the total length of the lens, effectively improve the resolution, effectively correct aberrations and realize the optical zoom function.

[0064] Table 5 is... Figure 9A , Figure 9B , Figure 9C Table of relevant parameters for each lens of the imaging lens 3 when it is at the wide-angle end, the middle end, and the telephoto end.

[0065] Table 5

[0066]

[0067]

[0068] Table 6 shows the relevant parameter values ​​of the imaging lens 3 in the third embodiment and the calculated values ​​of the corresponding conditions (1) to (7). As can be seen from Table 6, the imaging lens 3 in the third embodiment can meet the requirements of conditions (1) to (7).

[0069] Table 6

[0070]

[0071] Furthermore, the optical performance of the imaging lens 3 in the third embodiment also meets the requirements. Figure 10A It can be seen that, at the wide-angle end, the longitudinal aberration of the imaging lens 3 in the third embodiment is between -0.015mm and 0.02mm. Figure 10B It can be seen that the field curvature of the imaging lens 3 in the third embodiment is between -0.01mm and 0.03mm at the wide-angle end. Figure 10C It can be seen that the distortion of the imaging lens 3 in the third embodiment is between 0% and 1% at the wide-angle end. Figure 11A It can be seen that the imaging lens 3 in the third embodiment, located at the middle end, has a longitudinal aberration between -0.015mm and 0.02mm. Figure 11B It can be seen that the field curvature of the imaging lens 3 in the third embodiment is between -0.05mm and 0.01mm at the middle end. Figure 11C It can be seen that the distortion of the imaging lens 3 in the third embodiment is between 0% and 2% at the middle end. Figure 12A It can be seen that the imaging lens 3 in the third embodiment, at the telescope distance, has a longitudinal aberration between -0.03mm and 0.01mm. Figure 12B It can be seen that the field curvature of the imaging lens 3 in the third embodiment at the telescope is between -0.03mm and -0.01mm. Figure 12C It can be seen that the distortion of the imaging lens 3 in the third embodiment is between 0% and 2% at the telescope. It is evident that the longitudinal aberration, field curvature, and distortion of the imaging lens 3 in the third embodiment can be effectively corrected, thereby obtaining better optical performance.

[0072] Besides its use in surveillance cameras, the aforementioned imaging lens can also be applied to advanced driver assistance systems in automobiles, especially in low-visibility environments such as at night or in rainy weather, where it can still capture clear images of the outside world for the driver's reference, thereby improving driving safety. Furthermore, a sight generally consists of an objective lens group, a telescopic lens group, and an eyepiece group. The aforementioned imaging lens can also be used directly as a sight to capture clear images of distant targets, or it can be used as an objective lens group combined with other telescopic lens groups and eyepiece groups to form a sight, which should also fall within the scope of this invention.

[0073] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. An imaging lens, characterized in that, include: A first lens group having positive refractive power, comprising a 1-1 lens and a 1-2 lens, wherein the 1-1 lens has positive refractive power and the 1-2 lens has positive refractive power, and the 1-1 lens and the 1-2 lens are arranged sequentially from the object side to the image side along the optical axis. A second lens group having negative refractive power, comprising at least two lenses having negative refractive power, including a 2-1 lens and a 2-2 lens, wherein the 2-1 lens has negative refractive power and the 2-2 lens has negative refractive power, and the 2-1 lens and the 2-2 lens are arranged sequentially along the optical axis from the object side to the image side. The third lens group has positive refractive power and includes lens 3-1, lens 3-2, lens 3-3 and lens 3-4. Lens 3-1 has positive refractive power, lens 3-2 has positive refractive power, lens 3-3 has negative refractive power and includes a concave surface facing the object side, and lens 3-4 has negative refractive power. as well as The fourth lens group, which has positive refractive power, includes a 4-1 lens, which has positive refractive power. The first lens group, the second lens group, the third lens group, and the fourth lens group are arranged sequentially along the optical axis from the object side to the image side; Lens 3-1, lens 3-2, and lens 3-3 are arranged sequentially along the optical axis from the object side to the image side, and these lenses are adjacent to each other.

2. The imaging lens as described in claim 1, characterized in that: The 1-1 lens is a biconvex lens, and includes one convex surface facing the object side and another convex surface facing the image side; the 1-2 lens includes one convex surface facing the object side. The 2-1 lens includes a concave surface facing the image side, and the 2-2 lens includes a concave surface facing the object side; The 3-4 lens is disposed between the 3-3 lens and the fourth lens group. The 3-1 lens is a biconvex lens and includes a convex surface facing the object side and another convex surface facing the image side. The 3-2 lens includes a convex surface facing the object side. The 3-3 lens is a biconcave lens and further includes another concave surface facing the image side. The 3-4 lens is a meniscus lens and includes a convex surface facing the object side and a concave surface facing the image side. The 4-1 lens includes a convex surface facing the object.

3. The imaging lens as claimed in claim 2, wherein the fourth lens group further includes a 4-2 lens disposed between the third lens group and the 4-1 lens, characterized in that: The 1-2 lenses are meniscus lenses, and further include a concave surface facing the image side; The 2-1 lens is a meniscus lens, and further includes a convex surface facing the object; The 2-2 lens is a meniscus lens, and further includes a convex surface facing the image side; The 3-2 lens is a meniscus lens, and further includes a concave surface facing the image side; The 4-1 lens is a biconvex lens, and further includes another convex surface facing the image side; and The 4-2 lens is a meniscus lens with negative refractive power, and includes a concave surface facing the object side and a convex surface facing the image side.

4. The imaging lens as claimed in claim 2, wherein the first lens group further includes lenses 1-3 disposed between the object side and lens 1-1, characterized in that: The 3-2 lens is a biconvex lens, and further includes another convex surface facing the image side; The 4-1 lens is a meniscus lens, and further includes a concave surface facing the image side; and The 1-3 lenses are meniscus lenses with negative refractive power, and include a convex surface facing the object side and a concave surface facing the image side.

5. The imaging lens as described in claim 4, characterized in that: The 1-2 lens is a biconvex lens and further includes another convex surface facing the image side; The 2-1 lens is a biconcave lens and further includes another concave surface facing the object side; and The 2-2 lens is a biconcave lens and further includes another concave surface facing the image side.

6. The imaging lens as claimed in claim 4, wherein the second lens group further includes a 2-3 lens disposed between the 2-2 lens and the third lens group, characterized in that: The 1-2 lenses are meniscus lenses and further include a concave surface facing the image side; The 2-1 lens is a meniscus lens and further includes a convex surface facing the object; The 2-2 lens is a meniscus lens and further includes a convex surface facing the image side; and The 2-3 lens is a meniscus lens with positive refractive power, and includes a convex surface facing the object side and a concave surface facing the image side.

7. The imaging lens as described in claim 1, characterized in that, The third lens group further includes an aperture disposed between the second lens group and the 3-1 lens.

8. The imaging lens as described in claim 1, characterized in that, The spacing between these lens groups can be changed along the optical axis to allow the imaging lens to zoom from the wide-angle end to the middle end and then to the telephoto end to change the focal length. The fourth lens group can move along the optical axis to focus.

9. The imaging lens as described in claim 1, characterized in that, The imaging lens must meet at least one of the following conditions: -0.34 degrees / mm ≤ FOV / f1 ≤ 0.49 degrees / mm; -0.36 ≤ fG1 / f1 ≤ 0.68; -0.13 ≤ fG2 / fG23 ≤ 0.55; 18 ≤ TTL / TG34 ≤ 74; Wherein, FOV is the maximum field of view of the imaging lens, f1 is the effective focal length of the lens closest to the object side, fG1 is the effective focal length of the first lens group, fG2 is the effective focal length of the second lens group, fG23 is the effective focal length of the lens closest to the image side in the second lens group, TTL is the distance from the object side of the lens closest to the object side in the first lens group to the imaging plane along the optical axis, and TG34 is the thickness of the lens closest to the image side in the third lens group along the optical axis.

10. The imaging lens as described in claim 1, characterized in that, The imaging lens must meet at least one of the following conditions: 90 ≤ VdG1+VdG3 ≤ 107; -3.9 ≤ (L1R1×L1R2) / (L2R1×L2R2) ≤ -0.05; 65 ≤ VdG31+VdG34 ≤ 100; Wherein, VdG1 is the average Abbe coefficient of all lenses in the first lens group, VdG3 is the average Abbe coefficient of all lenses in the third lens group, L1R1 is the radius of curvature of the object side of the lens closest to the object side, L1R2 is the radius of curvature of the image side of the lens closest to the object side, L2R1 is the radius of curvature of the object side of the second lens closest to the object side, L2R2 is the radius of curvature of the image side of the second lens closest to the object side, VdG31 is the Abbe coefficient of the lens closest to the object side in the third lens group, and VdG34 is the Abbe coefficient of the lens closest to the image side in the third lens group.

Images