A fixed-focus lens

Abstract

An embodiment of the present invention provides a fixed-focus lens, which relates to the technical field of optical lenses. The fixed-focus lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged in sequence from the object side to the image side along the optical axis; the first lens, the third lens, and the fifth lens have negative optical powers, the fourth lens and the sixth lens have positive optical powers, and the second lens has a positive optical power or a negative optical power. An embodiment of the present invention provides a fixed-focus lens to achieve a large aperture, a small volume, a low cost, and stable high and low temperature performance of the fixed-focus lens.

Description

Technical Field

[0001] The present invention relates to the technology of optical lenses, and particularly to a fixed-focus lens. Background Art

[0002] With the rapid development of technology, people have a higher understanding of security, and surveillance lenses have emerged accordingly. With the increasing development of security surveillance systems, the requirements for security lenses are getting higher and higher, mainly reflected in higher image quality, larger field of view, larger light aperture, and larger target surface. Summary of the Invention

[0003] Embodiments of the present invention provide a fixed-focus lens to achieve a large aperture, small volume, low cost, and stable performance at high and low temperatures for the fixed-focus lens.

[0004] Embodiments of the present invention provide a fixed-focus lens, which includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged in sequence from the object side to the image side along the optical axis;

[0005] The first lens, the third lens, and the fifth lens have negative optical powers, the fourth lens and the sixth lens have positive optical powers, and the second lens has a positive optical power or a negative optical power.

[0006] Optionally, it further includes a diaphragm, and the diaphragm is located between the second lens and the third lens, or the diaphragm is located between the third lens and the fourth lens.

[0007] Optionally, the object side surface of the first lens is concave, and the image side surface of the first lens is concave or convex;

[0008] The object side surface of the second lens is concave, and the image side surface of the second lens is convex;

[0009] The object side surface of the third lens is convex, and the image side surface of the third lens is concave;

[0010] The object side surface of the fourth lens is convex, and the image side surface of the fourth lens is convex;

[0011] The object side surface of the fifth lens is convex, and the image side surface of the fifth lens is concave;

[0012] The object side surface of the sixth lens is convex, and the image side surface of the sixth lens is convex.

[0013] Optionally, the first lens and the fourth lens are glass spherical lenses;

[0014] The second lens, the third lens, the fifth lens, and the sixth lens are plastic aspherical lenses.

[0015] Optionally, the fourth lens is a glass spherical lens;

[0016] The first lens, the second lens, the third lens, the fifth lens and the sixth lens are plastic aspherical lenses.

[0017] Optionally, it satisfies:

[0018] -0.459 < φ1 / φ < -0.090;

[0019] -0.123 < φ2 / φ < 0.245;

[0020] -0.295 < φ3 / φ < -0.009;

[0021] 0.643 < φ4 / φ < 1.089;

[0022] -1.199 < φ5 / φ < -0.896;

[0023] 1.002 < φ6 / φ < 1.291;

[0024] Wherein, φ1 is the optical power of the first lens, φ2 is the optical power of the second lens, φ3 is the optical power of the third lens, φ4 is the optical power of the fourth lens, φ5 is the optical power of the fifth lens, φ6 is the optical power of the sixth lens, and φ is the optical power of the fixed-focus lens.

[0025] Optionally, it satisfies:

[0026] 1.52 ≤ n1 ≤ 1.69;

[0027] 1.40 ≤ n2 ≤ 1.71;

[0028] 1.48 ≤ n3 ≤ 1.76;

[0029] 1.40 ≤ n4 ≤ 1.65;

[0030] 1.59 ≤ n5 ≤ 1.70;

[0031] 1.46 ≤ n6 ≤ 1.59;

[0032] Wherein, n1 is the refractive index of the first lens, n2 is the refractive index of the second lens, n3 is the refractive index of the third lens, n4 is the refractive index of the fourth lens, n5 is the refractive index of the fifth lens, and n6 is the refractive index of the sixth lens.

[0033] Optionally, it satisfies:

[0034] 33.6 ≤ v1 ≤ 95;

[0035] 23.8 ≤ v2 ≤ 95;

[0036] 26.2 ≤ v3 ≤ 39.7;

[0037] 37.8 ≤ v4 ≤ 61;

[0038] 16.4 ≤ v5 ≤ 35;

[0039] 39.2 ≤ v6 ≤ 95;

[0040] Wherein, v1 is the dispersion coefficient of the first lens, v2 is the dispersion coefficient of the second lens, v3 is the dispersion coefficient of the third lens, v4 is the dispersion coefficient of the fourth lens, v5 is the dispersion coefficient of the fifth lens, and v6 is the dispersion coefficient of the sixth lens.

[0041] Optionally, it satisfies:

[0042] IC / TTL ≥ 0.310;

[0043] Wherein, IC is the image plane diameter of the fixed-focus lens, and TTL is the total length of the fixed-focus lens.

[0044] Optionally, it satisfies:

[0045] BFL / TTL ≥ 0.30;

[0046] Wherein, BFL is the back focal length of the fixed-focus lens, and TTL is the total length of the fixed-focus lens.

[0047] An embodiment of the present invention provides a fixed-focus lens. The first lens has a negative optical power, the second lens has a positive or negative optical power, the third lens has a negative optical power, the fourth lens has a positive optical power, the fifth lens has a negative optical power, and the sixth lens has a positive optical power, thereby achieving a large aperture, small volume, low cost, and stable high and low temperature performance of the fixed-focus lens. Description of the Drawings

[0048] Figure 1 It is a specific structure diagram of a fixed-focus lens in the first embodiment;

[0049] Figure 2 It is a spherical aberration curve diagram of a fixed-focus lens in the first embodiment;

[0050] Figure 3 It is a chromatic aberration curve diagram of a fixed-focus lens in the first embodiment;

[0051] Figure 4 It is a specific structure diagram of a fixed-focus lens in the second embodiment;

[0052] Figure 5 It is a spherical aberration curve diagram of a fixed-focus lens in the second embodiment;

[0053] Figure 6 It is the chromatic aberration curve graph of a fixed-focus lens in the second embodiment

[0054] Figure 7 It is the specific structure diagram of a fixed-focus lens in the third embodiment

[0055] Figure 8 It is the spherical aberration curve graph of a fixed-focus lens in the third embodiment

[0056] Figure 9 It is the chromatic aberration curve graph of a fixed-focus lens in the third embodiment Specific implementation manner

[0057] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. In addition, it should be noted that for the convenience of description, only the parts related to the present invention rather than all the structures are shown in the drawings.

[0058] Embodiment 1

[0059] Figure 1 It is the specific structure diagram of a fixed-focus lens in the first embodiment. Referring to Figure 1 , the fixed-focus lens includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, and a sixth lens 6 arranged in sequence from the object side to the image side along the optical axis. Among them, the first lens 1, the third lens 3, and the fifth lens 5 have negative optical powers, the fourth lens 4 and the sixth lens 6 have positive optical powers, and the second lens 2 has a positive optical power.

[0060] The embodiment of the present invention provides a fixed-focus lens. The first lens 1 has a negative optical power, the second lens 2 has a positive or negative optical power, the third lens 3 has a negative optical power, the fourth lens 4 has a positive optical power, the fifth lens 5 has a negative optical power, and the sixth lens 6 has a positive optical power, thereby realizing a large aperture, small volume, low cost, and stable high and low temperature performance of the fixed-focus lens.

[0061] Optionally, the fixed-focus lens further includes a diaphragm STOP, and the diaphragm STOP is located between the second lens 2 and the third lens 3.

[0062] Optionally, the object side of the first lens 1 is concave, and the image side of the first lens 1 is concave, that is, the first lens 1 is a biconcave lens. The object side of the second lens 2 is concave, and the image side of the second lens 2 is convex, that is, the second lens 2 is a concave-convex lens. The object side of the third lens 3 is convex, and the image side of the third lens 3 is concave, that is, the third lens 3 is a convex-concave lens. The object side of the fourth lens 4 is convex, and the image side of the fourth lens 4 is convex, that is, the fourth lens 4 is a biconvex lens. The object side of the fifth lens 5 is convex, and the image side of the fifth lens 5 is concave, that is, the fifth lens 5 is a convex-concave lens. The object side of the sixth lens 6 is convex, and the image side of the sixth lens 6 is convex, that is, the sixth lens 6 is a biconvex lens.

[0063] Optionally, the first lens 1 and the fourth lens 4 are glass spherical lenses. The second lens 2, the third lens 3, the fifth lens 5 and the sixth lens 6 are plastic aspherical lenses. An embodiment of the present invention provides a telephoto lens with F.NO < 1.56, which adopts a combination of glass and plastic lenses, achieving the characteristics of low cost and stable performance at high and low temperatures. It can meet the usage conditions of -40°C to 80°C, and can be maximally matched with a 1 / 2.7" target surface sensor chip, featuring small size, small purple fringing, small distortion, and day-night confocal.

[0064] Optionally, the optical powers of the first lens 1 to the sixth lens 6 satisfy: -0.459 < φ1 / φ < -0.090, -0.123 < φ2 / φ < 0.245, -0.295 < φ3 / φ < -0.009, 0.643 < φ4 / φ < 1.089, -1.199 < φ5 / φ < -0.896, 1.002 < φ6 / φ < 1.291. Wherein, φ1 is the optical power of the first lens 1, φ2 is the optical power of the second lens 2, φ3 is the optical power of the third lens 3, φ4 is the optical power of the fourth lens 4, φ5 is the optical power of the fifth lens 5, φ6 is the optical power of the sixth lens 6, and φ is the optical power of the fixed-focus lens.

[0065] Optionally, the refractive indices of the first lens 1 to the sixth lens 6 satisfy: 1.52 ≤ n1 ≤ 1.69, 1.40 ≤ n2 ≤ 1.71, 1.48 ≤ n3 ≤ 1.76, 1.40 ≤ n4 ≤ 1.65, 1.59 ≤ n5 ≤ 1.70, 1.46 ≤ n6 ≤ 1.59. Wherein, n1 is the refractive index of the first lens 1, n2 is the refractive index of the second lens 2, n3 is the refractive index of the third lens 3, n4 is the refractive index of the fourth lens 4, n5 is the refractive index of the fifth lens 5, and n6 is the refractive index of the sixth lens 6.

[0066] Optionally, the Abbe numbers of the first lens 1 to the sixth lens 6 satisfy: 33.6 ≤ v1 ≤ 95, 23.8 ≤ v2 ≤ 95, 26.2 ≤ v3 ≤ 39.7, 37.8 ≤ v4 ≤ 61, 16.4 ≤ v5 ≤ 35, 39.2 ≤ v6 ≤ 95. Wherein, v1 is the Abbe number of the first lens 1, v2 is the Abbe number of the second lens 2, v3 is the Abbe number of the third lens 3, v4 is the Abbe number of the fourth lens 4, v5 is the Abbe number of the fifth lens 5, and v6 is the Abbe number of the sixth lens 6.

[0067] Optionally, the fixed-focus lens satisfies: IC / TTL ≥ 0.310. Wherein, IC is the image plane diameter of the fixed-focus lens, and TTL is the total length of the fixed-focus lens. When IC / TTL ≥ 0.310, the fixed-focus lens has a larger target surface and a smaller volume, that is, it can ensure that the fixed-focus lens has better imaging quality and a clearer picture while having a smaller volume.

[0068] Optionally, the fixed-focus lens satisfies: BFL / TTL ≥ 0.30. Wherein, BFL is the back focal length of the fixed-focus lens, and TTL is the total length of the fixed-focus lens. When BFL / TTL ≥ 0.30, the back focal length of the fixed-focus lens is not too small, so that there is enough installation space for the imaging sensor and the flat filter.

[0069] Table 1 shows a set of design values of the fixed-focus lens in Embodiment 1

[0070] Surface Serial Number Surface Type Radius of Curvature (mm) Thickness (mm) Refractive Index Dispersion Coefficient Semi-Diameter S1 Spherical Surface -20.76 1.83 1.57 34.6 3.348 S2 Spherical Surface 45.89 1.29 2.852 S3 Aspherical Surface -3.4 2.49 1.64 39.6 2.600 S4 Aspherical Surface -3.96 0.1 3.334 Diaphragm Plane Infinity 0.1 3.197 S6 Aspherical Surface 11.7 0.72 1.54 35.4 3.366 S7 Aspherical Surface 8.64 0.1 3.390 S8 Spherical Surface 7.94 3.04 1.44 38.8 4.200 S9 Spherical Surface -8.33 0.1 4.200 S10 Aspherical Surface 7.88 1.73 1.64 22.8 3.362 S11 Aspherical Surface 2.69 0.31 3.045 S12 Aspherical Surface 4.89 3.46 1.54 91.1 2.900 S13 Aspherical Surface -9.97 5.3 2.999 S14 Plane Infinity 0.7 1.52 64.21 3.600 S15 Plane Infinity 0.82 3.600

[0071] Table 1 shows a set of design values of the fixed-focus lens in Embodiment 1, and the specific numerical values can be adjusted according to product requirements, which is not a limitation on the embodiments of the present invention. The fixed-focus lens shown in Table 1 can be Figure 1 As shown in. A lens generally includes two surfaces, and each surface is a refractive surface. The surface numbers in Table 1 are numbered according to the surfaces of each lens. Among them, the surface number "S1" represents the front surface of the first lens 1, the surface number "S2" represents the back surface of the first lens 1, and so on, which will not be elaborated here. It should be noted that the radius of curvature represents the degree of curvature of the lens surface. A positive radius of curvature value indicates that the center of curvature is on the image side of the surface, and a negative radius of curvature value represents that the center of curvature is on the side of the surface away from the image side. The value in the "Thickness" column represents the axial distance from the current surface to the next surface. The "Refractive Index" column represents the refractive index of the medium between the current surface and the next surface. The blank in the "Refractive Index" column is the refractive index of air, and the refractive index of air is 1. The Abbe number represents the dispersion characteristic of the material between the current surface and the next surface to light, and the blank represents that the current position is air.

[0072] Optionally, the aspheric formula is as follows:

[0073]

[0074] Among them, Z is the sag height of the aspheric surface, c is the basic curvature at the vertex, k is the conic constant, r is the radial coordinate in the direction perpendicular to the optical axis, a i is the coefficient of the higher-order term, a i r 2i is the higher-order term of the aspheric surface.

[0075] Table 2 shows a design value of the aspheric coefficients of the lenses in the fixed-focus lens in the first embodiment

[0076]

[0077]

[0078] Table 2 shows a design value of the aspheric coefficients of the lenses in the fixed-focus lens in the first embodiment. The specific numerical values can be adjusted according to the product requirements and are not a limitation to the embodiments of the present invention. The fixed-focus lens shown in Table 2 can be Figure 1 as shown in. The meaning of the "surface serial number" column in Table 2 is the same as that in Table 1. For example, the surface serial number "S3" also represents the front surface of the second lens 2. "E" in each embodiment of the present invention represents the exponent with base 10.

[0079] Embodiment 2

[0080] The same parts as in Embodiment 1 will not be described again. The difference from Embodiment 1 is that the second lens 2 has a negative optical power. The first lens 1 is a plastic aspheric lens.

[0081] Table 3 shows a design value of the fixed-focus lens in the second embodiment

[0082] Surface Serial Number Surface Type Radius of Curvature (mm) Thickness (mm) Refractive Index Dispersion Coefficient Semi-Diameter S1 Aspherical Surface -15.5 1.14 1.64 95 3.383 S2 Aspherical Surface 84.12 1.31 3.014 S3 Aspherical Surface -3.37 2.17 1.43 95 2.800 S4 Aspherical Surface -4.12 0.32 3.364 Diaphragm [[ID=!51]]Plane Infinity 0.45 3.164 S6 Aspherical Surface 12.33 0.7 1.71 27.2 3.389 S7 Aspherical Surface 8.26 0.1 3.449 S8 Spherical Surface 7.35 3.5 1.6 48 4.200 S9 Spherical Surface -9.37 0.1 4.200 S10 Aspherical Surface 7.65 1.28 1.65 34 3.536 S11 Aspherical Surface 2.6 0.25 3.227 S12 Aspherical Surface 4.12 3.15 1.51 95 3.100 S13 Aspherical Surface -10.04 5.3 3.083 S14 Plane Infinity 0.7 1.52 64.21 3.600 S15 Plane Infinity 1.54 3.600

[0083] Table 3 shows a design value of the fixed-focus lens in the second embodiment. The specific numerical values can be adjusted according to the product requirements and are not a limitation to the embodiments of the present invention. The fixed-focus lens shown in Table 3 can be Figure 4 as shown in.

[0084] Table 4 shows a design value of the aspheric coefficients of the lenses in the fixed-focus lens in the second embodiment

[0085]

[0086] Table 4 shows a design value of the aspheric coefficients of the lenses in the fixed-focus lens in the second embodiment. The specific numerical values can be adjusted according to the product requirements and are not a limitation to the embodiments of the present invention. The fixed-focus lens shown in Table 4 can be Figure 4 as shown in.

[0087] Embodiment 3

[0088] The same parts as those in Embodiment 1 will not be described in detail. The difference from Embodiment 1 is that the aperture STOP is located between the third lens 3 and the fourth lens 4. The object side surface of the first lens 1 is concave, and the image side surface of the first lens 1 is convex. The first lens 1 is a concave-convex lens.

[0089] Table 5 shows a set of design values of the fixed-focus lens in Embodiment 3

[0090] Surface Serial Number Surface Type Radius of Curvature (mm) Thickness (mm) Refractive Index Dispersion Coefficient Semi-Diameter S1 Spherical Surface -17.13 2.1 1.62 70 3.350 S2 Spherical Surface -60.17 1.23 2.885 S3 Aspherical Surface -3.36 2.51 1.66 24.8 2.600 S4 Aspherical Surface -3.97 0.35 3.361 s5 Aspherical Surface 13 0.7 1.53 38.7 3.364 S6 Aspherical Surface 9.18 0.72 3.371 Diaphragm Plane Infinity -0.6 3.254 S8 Spherical Surface 8.14 3.01 1.44 60 4.200 S9 Spherical Surface -8.29 0.1 4.200 S10 Aspherical Surface 7.96 1.69 1.64 17.4 3.361 S11 Aspherical Surface 2.68 0.33 3.043 S12 Aspherical Surface 4.99 3.36 1.54 40.2 2.900 S13 Aspherical Surface -9.86 5.3 3.019 S14 Plane Infinity 0.7 1.52 64.21 3.600 S15 Plane Infinity 0.72 3.600

[0091] Table 5 shows a set of design values of the fixed-focus lens in Embodiment 3. The specific numerical values can be adjusted according to product requirements and are not limitations on the embodiments of the present invention. The fixed-focus lens shown in Table 5 can be Figure 7 as shown in

[0092] Table 6 shows a set of design values of the aspherical coefficients of the lenses in the fixed-focus lens in Embodiment 3

[0093]

[0094]

[0095] Table 6 shows a set of design values of the aspherical coefficients of the lenses in the fixed-focus lens in Embodiment 3. The specific numerical values can be adjusted according to product requirements and are not limitations on the embodiments of the present invention. The fixed-focus lens shown in Table 6 can be Figure 7 as shown in

[0096] Note that the above are only the preferred embodiments of the present invention and the technical principles applied. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described here. Various obvious changes, re-adjustments, combinations with each other, and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments only. Without departing from the concept of the present invention, it can also include more other equivalent embodiments, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A fixed-focus lens, characterized in that, It includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged in sequence from the object side to the image side along the optical axis; The first lens, the third lens, and the fifth lens have negative optical powers, the fourth lens and the sixth lens have positive optical powers, and the second lens has a positive or negative optical power; The object side surface of the first lens is concave, and the image side surface of the first lens is concave or convex; The object side surface of the second lens is concave, and the image side surface of the second lens is convex; The object side surface of the third lens is convex, and the image side surface of the third lens is concave; The object side surface of the fourth lens is convex, and the image side surface of the fourth lens is convex; The object side surface of the fifth lens is convex, and the image side surface of the fifth lens is concave; The object side surface of the sixth lens is convex, and the image side surface of the sixth lens is convex; The first lens and the fourth lens are glass spherical lenses; The second lens, the third lens, the fifth lens, and the sixth lens are plastic aspherical lenses; The fourth lens is a glass spherical lens; The first lens, the second lens, the third lens, the fifth lens, and the sixth lens are plastic aspherical lenses; -0.459 < φ1 / φ < -0.090; -0.123 < φ2 / φ < 0.245; -0.295 < φ3 / φ < -0.009; 0.643 < φ4 / φ < 1.089; -1.199 < φ5 / φ < -0.896; 1.002 < φ6 / φ < 1.291; Wherein, φ1 is the optical power of the first lens, φ2 is the optical power of the second lens, φ3 is the optical power of the third lens, φ4 is the optical power of the fourth lens, φ5 is the optical power of the fifth lens, φ6 is the optical power of the sixth lens, and φ is the optical power of the fixed-focus lens.

2. The fixed-focus lens according to claim 1, wherein It further includes a diaphragm, and the diaphragm is located between the second lens and the third lens, or the diaphragm is located between the third lens and the fourth lens.

3. The fixed-focus lens according to claim 1, wherein Satisfy: 1.52≤n1≤1.69； 1.40≤n2≤1.71； 1.48≤n3≤1.76； 1.40≤n4≤1.65； 1.59≤n5≤1.70； 1.46≤n6≤1.59； Wherein, n1 is the refractive index of the first lens, n2 is the refractive index of the second lens, n3 is the refractive index of the third lens, n4 is the refractive index of the fourth lens, n5 is the refractive index of the fifth lens, and n6 is the refractive index of the sixth lens.

4. The fixed-focus lens according to claim 1, characterized in that, Satisfy: 33.6≤v1≤95； 23.8≤v2≤95； 26.2≤v3≤39.7； 37.8≤v4≤61； 16.4≤v5≤35； 39.2≤v6≤95； Wherein, v1 is the dispersion coefficient of the first lens, v2 is the dispersion coefficient of the second lens, v3 is the dispersion coefficient of the third lens, v4 is the dispersion coefficient of the fourth lens, v5 is the dispersion coefficient of the fifth lens, and v6 is the dispersion coefficient of the sixth lens.

5. The fixed-focus lens according to claim 1, wherein, Satisfy: IC / TTL ≥ 0.310; Wherein, IC is the image plane diameter of the fixed-focus lens, and TTL is the total length of the fixed-focus lens.

6. The fixed-focus lens according to claim 1, wherein Satisfy: BFL / TTL ≥ 0.30; Wherein, BFL is the back focal length of the fixed-focus lens, and TTL is the total length of the fixed-focus lens.

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