CN218158528U - Fixed focus lens - Google Patents
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- CN218158528U CN218158528U CN202222249318.6U CN202222249318U CN218158528U CN 218158528 U CN218158528 U CN 218158528U CN 202222249318 U CN202222249318 U CN 202222249318U CN 218158528 U CN218158528 U CN 218158528U
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Abstract
The utility model discloses a fixed focus camera lens follows the direction of optical axis from the thing side to picture side, includes in proper order: a first lens with negative focal power, a second lens with negative focal power, a third lens with positive focal power, a fourth lens with positive focal power, a fifth lens with positive or negative focal power, a sixth lens with positive focal power, a seventh lens with negative focal power, and an eighth lens with positive focal power, the second lens is a paraxial region convex-concave lens; the diaphragm is positioned between the third lens and the fourth lens or on the object side surface of the fourth lens, and the curvature radius R21 of the object side surface of the second lens, the curvature radius R22 of the image side surface of the second lens and the focal length F2 of the second lens satisfy the following relation: -0.45 is less than or equal to 0.5 (R21 + R22)/F2 is less than or equal to-0.1. The utility model discloses a tight shot has characteristics miniaturized, high performance, low cost, and the camera lens is at-40 ℃ - +80 ℃ temperature range formation of image clarity, and relative illuminance can reach more than 40%, satisfies the formation of image demand of light and shade environment.
Description
Technical Field
The utility model relates to an optical imaging field especially relates to a tight shot.
Background
With the popularization of work in the fields of security and public safety, the demand of monitoring the fixed-focus lens is rising day by day, wherein the ultra-large aperture lens has higher light transmission amount and better meets the market demand in performance, so the research and development design of the ultra-large aperture lens is necessary, however, the high light transmission amount usually means that more lenses are needed to correct aberration and chromatic aberration, and the lens has a complex structure, so that the material cost and the processing cost of the lens are difficult to control, and the popularization of the lens is not facilitated. When guaranteeing the camera lens performance, the lower the cost of camera lens, the more reasonable is the structure, can realize mass production more, just can satisfy the security protection demand that increases gradually. Therefore, how to reduce the cost under the condition of ensuring the performance of the lens is a technical problem to be solved by the existing ultra-large aperture monitoring lens.
Disclosure of Invention
The utility model aims to solve the problems and provide a fixed-focus lens with an ultra-large aperture, which has low cost, small volume and no virtual focus within the temperature range of-40 ℃ to 80 ℃.
To achieve the above object, the present invention provides a fixed focus lens, which includes in order along an optical axis from an object side to an image side: the optical lens comprises a first lens with negative focal power, a second lens with negative focal power, a third lens with positive focal power, a fourth lens with positive focal power, a fifth lens with positive or negative focal power, a sixth lens with positive focal power, a seventh lens with negative focal power and an eighth lens with positive focal power, wherein the second lens is a paraxial region convex-concave lens;
the diaphragm is arranged between the third lens and the fourth lens or on the object side surface of the fourth lens;
the curvature radius R21 of the object side surface of the second lens, the curvature radius R22 of the image side surface of the second lens and the focal length F2 of the second lens satisfy the following relation:
-0.45≤0.5(R21+R22)/F2≤-0.1。
according to an aspect of the utility model, the first lens is paraxial region convex-concave lens, the third lens is paraxial region convex-concave lens, the fourth lens is convex-convex lens, the fifth lens is paraxial region convex-concave lens, the sixth lens is paraxial region convex-convex lens, the seventh lens is paraxial region concave-concave lens, the eighth lens is paraxial region convex-convex lens.
According to an aspect of the present invention, the first lens, the second lens, the third lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens are aspheric lenses;
the fourth lens is a spherical lens.
According to an aspect of the present invention, the first lens, the second lens, the third lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens are plastic lenses;
the fourth lens is a glass lens.
According to the utility model discloses an aspect, the optics total length TTL of tight shot with the back focal length BFL of tight shot satisfies following relation:
4.8≤TTL/BFL≤5.2。
according to the utility model discloses an aspect, the optics total length TTL of tight shot with the effective focal length F of tight shot satisfies following relation:
5.6≤TTL/F≤6.9。
according to an aspect of the present invention, the curvature radius R11 of the object side surface of the first lens and the effective focal length F of the fixed-focus lens satisfy the following relationship:
0≤F/R11≤0.2。
according to an aspect of the present invention, the distance D34 between the third lens element and the fourth lens element satisfies the following relationship with the distance T2 between the fourth lens element and the image plane side:
0≤D34/T2≤0.05。
according to the utility model discloses an aspect, the diaphragm with distance D0 between the object side of fourth lens satisfies following relation:
D0≤0。
according to an aspect of the present invention, the rise SAG41 of the object side surface of the fourth lens satisfies the following relationship:
0.45≤SAG41≤0.6。
according to an aspect of the present invention, the rise SAG51 of the object-side surface of the fifth lens and the optically effective half aperture D1 of the fifth lens satisfy the following relationship:
-0.5≤SAG51/D1≤-0.3。
according to an aspect of the present invention, the curvature radius R81 of the object side surface of the eighth lens element, the curvature radius R82 of the image side surface of the eighth lens element, and the effective focal length F8 of the object side surface of the eighth lens element satisfy the following relationship:
-0.35≤0.5(R81+R82)/F8≤-0.1。
according to the utility model discloses an aspect, the sixth lens the seventh lens with the combined focal length F678 of eighth lens with the effective focal length F of tight shot satisfies following relation:
2.1≤F678/F≤2.7。
according to the utility model discloses a scheme, the utility model discloses a tight shot through the focal power of each lens of rational distribution, optimizes the shape that sets up each lens, can realize the high resolution performance of camera lens for relative illuminance is more than 40%, on realizing miniaturized basis, has the relatively longer characteristic of back focus, is favorable to the equipment of tight shot, the production of being convenient for.
According to the utility model discloses a scheme is through the rise of optimizing configuration each diaphragm position and fourth lens object side, the utility model discloses a tight shot can realize big light ring, and the FNO number of light ring can reach 1.06, and the diaphragm can increase the light inlet quantity in the position of front group, makes relative illuminance reach more than 40%, satisfies the formation of image demand of light and shade environment.
According to the utility model discloses a scheme adopts aspheric lens can adjust system's aberration high-efficiently, and the plastic material can realize the low cost of camera lens, can realize simultaneously that the formation of image is clear not virtual burnt at-40 deg.C 80 ℃ temperature range, has overcome plastic aspheric lens because coefficient of expansion is big, causes the difficulty of focus drift under high low temperature environment easily.
According to the utility model discloses a scheme is through each lens diopter of rational configuration and focus, the utility model discloses a aberration that produces when the tight shot can effectively avoid light to incide reduces the shaping sensitivity of lens, is favorable to the production of first lens, guarantees production quality.
According to one embodiment of the present invention, the second lens is a convex-concave lens, which is favorable for converging light rays and making the light rays diffused by the first lens enter the rear part smoothly; the second lens has a reverse curvature point, which is beneficial to improving the resolution, and the appropriate ratio between the curvature and the focal length can reduce the coma aberration and the field curvature when the light enters the system.
According to the utility model discloses a scheme, through the effective semi-bore of rise of rational configuration fifth lens object side, sixth lens, seventh lens and the focus of eighth lens with the ratio relation of the effective focal length of tight shot is favorable to guaranteeing that the mirror surface type is mild, reduces the shaping sensitivity, improves the resolution.
According to the utility model discloses a scheme is favorable to reducing the remaining aberration of light behind optical system through the curvature radius and the focus of rational configuration eighth lens object side, image side of last lens.
Drawings
Fig. 1 is a schematic structural view of a fixed focus lens according to embodiment 1 of the present invention;
fig. 2 is a schematic view of a light fan of a fixed focus lens according to embodiment 1 of the present invention;
fig. 3 is a schematic structural view of a fixed focus lens according to embodiment 2 of the present invention;
fig. 4 is a schematic view of a light fan of a fixed focus lens according to embodiment 2 of the present invention;
fig. 5 is a schematic structural view of a fixed focus lens according to embodiment 3 of the present invention;
fig. 6 is a schematic view of a light fan of a fixed focus lens according to embodiment 3 of the present invention;
fig. 7 is a schematic structural view of a fixed focus lens according to embodiment 4 of the present invention;
fig. 8 is a schematic view of a light fan of a fixed-focus lens according to embodiment 4 of the present invention.
Detailed Description
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
In describing embodiments of the present invention, the terms "longitudinal," "lateral," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and other terms are used in an orientation or positional relationship shown in the associated drawings for convenience in describing the invention and for simplicity in description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be construed as limiting the invention.
The present invention will be described in detail with reference to the accompanying drawings and specific embodiments, which are not repeated herein, but the present invention is not limited to the following embodiments.
Fig. 1 is a view schematically showing a structure of a fixed focus lens according to an embodiment of the present invention. As shown in fig. 1, the fixed focus lens of the present invention sequentially includes, along the direction from the object side to the image side along the optical axis: a first lens L1 with negative focal power, a second lens L2 with negative focal power, a third lens L3 with positive focal power, a fourth lens L4 with positive focal power, a fifth lens L5 with positive or negative focal power, a sixth lens L6 with positive focal power, a seventh lens L7 with negative focal power, an eighth lens L8 with positive focal power, and the second lens L2 is a paraxial region convex-concave lens;
the stop STO is disposed between the third lens L3 and the fourth lens L4 or on the object-side surface of the fourth lens L4;
the radius of curvature R21 of the object-side surface of the second lens L2, the radius of curvature R22 of the image-side surface of the second lens L2, and the focal length F2 of the second lens L2 satisfy the following relationship:
-0.45≤0.5(R21+R22)/F2≤-0.1。
by reasonably distributing the focal power of each lens and optimally setting the shape of each lens, the high-resolution performance of the lens can be realized, so that the relative illumination is more than 40%, and when the parameters of the second lens L2 meet the relational expression, the converging light is more facilitated, and the light rays diffused by the first lens L1 smoothly enter the rear part; the second lens L2 has a point of inflection, which is advantageous for improving the resolution, and when the above-mentioned relation is satisfied between the curvature and the focal length, the coma aberration and the field curvature in the light incident system can be more effectively reduced.
In the present invention, along the direction from the object side to the image side, the first lens L1 is a paraxial region convex-concave lens, the fourth lens L4 is a convex-convex lens, the fifth lens L5 is a paraxial region convex-concave lens, the sixth lens L6 is a paraxial region convex-convex lens, the third lens L3 is a paraxial region convex-concave lens, the seventh lens L7 is a paraxial region concave-concave lens, and the eighth lens L8 is a paraxial region convex-convex lens.
The utility model discloses in, still include cover glass CG, cover glass CG is located eighth lens L8's image side.
In the present invention, along the direction from the object side to the image side, the first lens element L1, the second lens element L2, the third lens element L3, the fifth lens element L5, the sixth lens element L6, the seventh lens element L7, and the eighth lens element L8 are aspheric lens elements;
the fourth lens L4 is a spherical lens.
Wherein, the aspheric surface satisfies the following formula:
in the formula, z is the axial distance from the curved surface to the vertex at the position which is along the direction of the optical axis and is vertical to the optical axis by the height h; c represents the curvature at the apex of the aspherical surface; k is a conic coefficient; a4, A6, A8, A10, A12, A14 and A16 \8230: (four-order, six-order, eight-order, ten-order, twelve-order, fourteen-order and sixteen-order \8230;) aspheric coefficients.
In the present invention, the first lens element L1, the second lens element L2, the third lens element L3, the fifth lens element L5, the sixth lens element L6, the seventh lens element L7, and the eighth lens element L8 are plastic lenses;
the fourth lens L4 is a glass lens.
The system aberration can be efficiently adjusted by adopting the aspheric lens, the cost of the lens can be reduced by using the plastic material, and the lens can be imaged clearly in the temperature range of minus 40 ℃ to plus 80 ℃.
Furthermore, the utility model discloses a total optical length TTL of tight shot and back focus BFL of tight shot satisfy following relation: TTL/BFL is more than or equal to 4.8 and less than or equal to 5.2 when the relation is satisfied; the total optical length TTL of the fixed-focus lens and the effective focal length F of the fixed-focus lens satisfy the following relation: TTL/F is more than or equal to 5.6 and less than or equal to 6.9, the volume of the fixed focus lens is effectively reduced, and the miniaturization of the fixed focus lens is favorably realized.
The curvature radius R11 of the object side surface of the first lens L1 and the effective focal length F of the fixed-focus lens satisfy the following relation: F/R11 is more than or equal to 0 and less than or equal to 0.2, so that aberration generated when light rays are incident can be avoided, the forming sensitivity of the lens is reduced, the production of the first lens L1 is facilitated, the quality of the first lens L1 is ensured, and the imaging quality of the prime lens is improved.
The distance D34 between the image side surface of the third lens L3 and the object side surface of the fourth lens L4 and the distance T2 between the object side surface of the fourth lens L4 and the image surface satisfy the following relation: D34/T2 is more than or equal to 0 and less than or equal to 0.05, which is beneficial to ensuring the stability of the former group and reducing the sensitivity of the assembly process.
The front group is a lens group from the object side to the stop STO along the optical axis, and includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5.
The distance D0 between the stop STO and the object-side surface of the fourth lens L4 satisfies the following relationship: d0 is less than or equal to 0; the rise SAG41 of the object side surface of the fourth lens L4 satisfies the following relationship: SAG41 is more than or equal to 0.45 and less than or equal to 0.6. When the relation is met, the fixed-focus lens can realize a large aperture FNO1.06, and the diaphragm is arranged at the front group position, so that the light entering amount is increased, and the relative illumination reaches more than 40%.
The saggital height SAG51 of the object side surface of the fifth lens L5 and the optically effective half aperture D1 of the fifth lens L5 satisfy the following relationship: SAG51/D1 is more than or equal to-0.5 and less than or equal to-0.3, which is beneficial to ensuring the smoothness of the mirror surface and reducing the molding sensitivity.
The radius of curvature R81 of the object-side surface of the eighth lens L8, the radius of curvature R82 of the image-side surface of the eighth lens L8, and the focal length F8 of the object-side surface of the eighth lens L8 satisfy the following relationship: 0.35 to 0.5 (R81 + R82)/F8 to 0.1, which is beneficial to reducing the residual aberration of the light after passing through the optical system.
The focal length F678 of the sixth lens L6, the seventh lens L7, and the eighth lens L8 and the effective focal length F of the fixed-focus lens satisfy the following relationship: F678/F is not less than 2.1 and not more than 2.7, which is beneficial to smooth and transition of light, reduces tolerance sensitivity and improves resolution.
The distance T1 between the object side surface of the sixth lens and the image side surface of the eighth lens and the back focal length FL satisfy the following relation: T1/BFL is more than or equal to 1.30 and less than or equal to 1.35, and the lens has the characteristic of relatively long back focal length on the basis of realizing miniaturization, is favorable for assembling the fixed-focus lens and is convenient for production.
Synthesize above-mentioned setting, the utility model discloses a tight shot can realize that the camera lens overall length is less than or equal to 22.3mm, and camera lens back focal length is more than or equal to 4.3mm for the tight shot is more miniaturized, under the requirement that satisfies the high performance, adopts the aspheric lens of plastic material, has reduced manufacturing cost.
And the utility model discloses an optimize each lens diopter of configuration and choose for use reasonable material, the utility model discloses a FNO number of tight burnt camera lens can reach 1.06, realizes the characteristic of big light ring, and the quantity of light entering is enough under the circumstances of guaranteeing the imaging quality, satisfies the formation of image demand of light and shade environment.
Meanwhile, the utility model discloses can realize not virtual burnt at-40 deg.C-80 deg.C temperature range, overcome plastic aspheric lens because coefficient of expansion is big, cause the difficulty of focus drift under high low temperature environment easily.
The following description will be given of four groups of embodiments according to the present invention, as set forth above. Because the fixed focus lens according to the present invention has eight lenses in total, and the stop STO protective glass CG and the image plane IMA are added, when the stop STO is disposed on the object side surface of the fourth lens L4, there are 19 surfaces in total; when the stop STO is disposed between the third lens L3 and the fourth lens L4, a total of 20 surfaces. For convenience of description, the respective surfaces other than the image surface are numbered as S1, S2 to S19.
The data for the four sets of examples are as in table 1 below:
TABLE 1
Example 1:
fig. 1 is a schematic structural view of a fixed focus lens according to embodiment 1 of the present invention;
fig. 2 is a schematic view of a light fan of a fixed-focus lens according to embodiment 1 of the present invention.
The aperture FNO =1.07 and the total lens length is 22.27mm in example 1; the fifth lens L5 has positive power, and the stop STO is disposed between the third lens L3 and the fourth lens L4.
Table 2 below lists relevant parameters of each lens of the present embodiment, including surface type, radius of curvature, thickness, refractive index of material, abbe number:
| number of noodles | Surface type | Radius of curvature R | Thickness d | Refractive index Nd | Abbe number Vd |
| S1 | Aspherical surface | 19.71 | 0.80 | 1.54 | 55.7 |
| S2 | Aspherical surface | 2.99 | 2.87 | ||
| S3 | Aspherical surface | 6.29 | 1.29 | 1.54 | 55.7 |
| S4 | Aspherical surface | 2.78 | 0.32 | ||
| S5 | Aspherical surface | 9.86 | 2.39 | 1.64 | 23.5 |
| S6 | Aspherical surface | 27.55 | 0.56 | ||
| STO | Spherical surface | Infinity | -0.44 | ||
| S8 | Spherical surface | 9.64 | 1.73 | 1.70 | 55.5 |
| S9 | Spherical surface | -9.64 | 0.71 | ||
| S10 | Aspherical surface | -3.46 | 1.50 | 1.54 | 55.7 |
| S11 | Aspherical surface | -3.80 | 0.18 | ||
| S12 | Aspherical surface | 4.54 | 2.18 | 1.54 | 55.7 |
| S13 | Aspherical surface | -24.37 | 0.04 | ||
| S14 | Aspherical surface | -15.94 | 0.80 | 1.64 | 23.5 |
| S15 | Aspherical surface | 4.51 | 0.33 | ||
| S16 | Aspherical surface | 4.74 | 2.51 | 1.54 | 55.7 |
| S17 | Aspherical surface | -8.75 | 3.50 | ||
| S18 | Spherical surface | Infinity | 0.80 | 1.52 | 64.2 |
| S19 | Spherical surface | Infinity | 0.20 | ||
| IMA | Spherical surface | Infinity | 0.00 |
TABLE 2
In the present embodiment, the aspheric data is shown in table 3 below, where K is the conic constant of the surface, and A4, A6, A8, a10, a12, a14, a16 are the aspheric coefficients of fourth order, sixth order, eighth order, tenth order, twelfth order, fourteenth order, and sixteenth order, respectively:
TABLE 3
Referring to fig. 1 to 2, in combination with tables 1 to 3, in this embodiment, the aperture of the fixed-focus lens can reach 1.07, and is applicable to a low-light-level environment, and the relative illumination reaches above 40%, and meanwhile, the lens can be clearly imaged within a temperature range of-40 ℃ to +80 ℃, and the back focus BFL is 4.5mm, and has the characteristics of miniaturization, low cost, and high performance.
Example 2:
fig. 3 is a schematic structural view of a fixed focus lens according to embodiment 2 of the present invention;
fig. 4 is a schematic view of a light fan of a fixed focus lens according to embodiment 2 of the present invention.
The aperture FNO =1.06 and the total lens length in example 2 was 22.19mm; the fifth lens L5 has positive power, and the stop STO is disposed between the third lens L3 and the fourth lens L4.
Table 4 below lists relevant parameters of each lens of the present embodiment, including surface type, radius of curvature, thickness, refractive index of material, abbe number:
TABLE 4
In the present embodiment, the aspheric data is shown in table 5 below, where K is the conic constant of the surface, and A4, A6, A8, a10, a12, a14, a16 are aspheric coefficients of fourth order, sixth order, eighth order, tenth order, twelfth order, and sixteenth order:
TABLE 5
Referring to fig. 3 to 4, in combination with table 1, table 4 and table 5, in this embodiment, the aperture of the fixed-focus lens can reach 1.06, and is suitable for a low-light-level environment, and the relative illumination reaches above 40%, and meanwhile, the lens can be clearly imaged within a temperature range of-40 ℃ to +80 ℃, and the back focus BFL is 4.3mm, and has the characteristics of miniaturization, low cost and high performance.
Example 3:
fig. 3 is a schematic structural view of a fixed focus lens according to embodiment 3 of the present invention;
fig. 4 is a schematic view of a light fan of a fixed focus lens according to embodiment 3 of the present invention.
The aperture FNO =1.06 and the total lens length in example 3 was 22.10mm; the fifth lens L5 has negative refractive power, and the stop STO is disposed on the object-side surface of the fourth lens L4.
Table 6 below lists relevant parameters of each lens of the present embodiment, including surface type, radius of curvature, thickness, refractive index of material, abbe number:
| noodle sequence number | Surface type | Radius of curvature R | Thickness d | Refractive index Nd | Abbe number Vd |
| S1 | Aspherical surface | 97.714 | 1.09 | 1.54 | 55.7 |
| S2 | Aspherical surface | 3.441 | 1.69 | ||
| S3 | Aspherical surface | 4.379 | 1.03 | 1.54 | 55.7 |
| S4 | Aspherical surface | 2.807 | 0.34 | ||
| S5 | Aspherical surface | 10.751 | 1.90 | 1.64 | 23.5 |
| S6 | Aspherical surface | 19.708 | 0.11 | ||
| S7 | Spherical surface | 9.004 | 2.50 | 1.70 | 55.5 |
| S8 | Spherical surface | -9.004 | 1.01 | ||
| S9 | Aspherical surface | -2.748 | 1.90 | 1.54 | 55.7 |
| S10 | Aspherical surface | -3.489 | 0.04 | ||
| S11 | Aspherical surface | 4.191 | 2.31 | 1.54 | 55.7 |
| S12 | Aspherical surface | -231.864 | 0.10 | ||
| S13 | Aspherical surface | -20.205 | 0.81 | 1.64 | 23.5 |
| S14 | Aspherical surface | 4.448 | 0.17 | ||
| S15 | Aspherical surface | 5.008 | 2.55 | 1.54 | 55.7 |
| S16 | Aspherical surface | -7.926 | 3.55 | ||
| S17 | Spherical surface | Infinity | 0.8 | 1.52 | 64.2 |
| S18 | Spherical surface | Infinity | 0.2 | ||
| IMA | Spherical surface | Infinity | 0 |
TABLE 6
In this embodiment, the aspheric data is shown in table 7 below, where K is the conic constant of the surface, and A4, A6, A8, a10, a12, a14, a16 are aspheric coefficients of fourth order, sixth order, eighth order, tenth order, twelfth order, and sixteenth order, respectively:
TABLE 7
Referring to fig. 5 to 6, in combination with table 1, table 7 and table 8, in this embodiment, the aperture of the fixed-focus lens can reach 1.06, and is applicable to a dim light environment, and the relative illumination reaches above 40%, and meanwhile, the lens can be clearly imaged within a temperature range of-40 ℃ to +80 ℃, and the back focus BFL is 4.55mm, and has the characteristics of miniaturization, low cost and high performance.
Example 4:
fig. 7 is a schematic structural view of a fixed focus lens according to embodiment 4 of the present invention;
fig. 8 is a schematic view of a light fan of a fixed-focus lens according to embodiment 4 of the present invention.
The aperture FNO =1.06 and the total lens length in example 4 was 22.11mm; the fifth lens L5 has negative power, and the stop STO is disposed on the object-side surface of the fourth lens L4.
Table 8 below lists relevant parameters of each lens of the present embodiment, including surface type, radius of curvature, thickness, refractive index of material, abbe number:
TABLE 8
In this example, the aspheric data is shown in Table 9 below, where K is the conic constant of the surface, A 4 、A 6 、A 8 、A 10 、A 12 、A 14 、A 16 Aspheric coefficients of fourth order, sixth order, eighth order, tenth order, twelfth order, fourteenth order and sixteenth order:
TABLE 9
Referring to fig. 7 to 8, in combination with table 1, table 8 and table 9, in this embodiment, the aperture of the fixed-focus lens can reach 1.06, and is applicable to a dim light environment, and the relative illumination reaches above 40%, and meanwhile, the lens can be clearly imaged within a temperature range of-40 ℃ to +80 ℃, and the back focal length BFL is 4.51mm, and the fixed-focus lens has the characteristics of miniaturization, low cost and high performance.
The utility model discloses a fixed focus camera lens, through the focal power of each lens of rational distribution, optimize the shape that sets up each lens, can realize the high resolution performance of camera lens, make relative illuminance more than 40%, on the basis of realizing the miniaturization, have the relatively longer characteristic of back focus, be favorable to the equipment of fixed focus camera lens, the production of being convenient for can realize big light ring, the FNO number of light ring can reach 1.06, and the light inlet amount can be increased in the position of diaphragm in the front group, make relative illuminance reach more than 40%, satisfy the formation of image demand of light and shade environment; the aspheric lens can efficiently adjust system aberration, the plastic material can realize low cost of the lens, and clear and non-virtual focus imaging can be realized at the temperature range of-40-80 ℃, the difficulty that the focus drifts easily under high and low temperature environments due to large expansion coefficient of the plastic aspheric lens is overcome, the aberration generated when light rays are incident is effectively avoided, the molding sensitivity of the lens is reduced, the production of the first lens is facilitated, and the production quality is ensured; meanwhile, coma and field curvature when light enters the system can be reduced, the surface of the mirror is ensured to be smooth, the forming sensitivity is reduced, and the resolution is improved.
The above description is only one embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (13)
1. A fixed focus lens sequentially includes, in a direction from an object side to an image side along an optical axis: a first lens (L1) with negative focal power, a second lens (L2) with negative focal power, a third lens (L3) with positive focal power, a fourth lens (L4) with positive focal power, a fifth lens (L5) with positive or negative focal power, a sixth lens (L6) with positive focal power, a seventh lens (L7) with negative focal power and an eighth lens (L8) with positive focal power, wherein the second lens (L2) is a paraxial region convex-concave lens;
a diaphragm (STO) is arranged between the third lens (L3) and the fourth lens (L4) or on the object side surface of the fourth lens (L4);
the radius of curvature R21 of the object-side surface of the second lens (L2), the radius of curvature R22 of the image-side surface of the second lens (L2), and the focal length F2 of the second lens (L2) satisfy the following relationship:
-0.45≤0.5(R21+R22)/F2≤-0.1。
2. the prime lens according to claim 1, wherein the first lens (L1) is a paraxial region convex-concave lens, the third lens (L3) is a paraxial region convex-concave lens, the fourth lens (L4) is a convex-convex lens, the fifth lens (L5) is a paraxial region convex-concave lens, the sixth lens (L6) is a paraxial region convex-convex lens, the seventh lens (L7) is a paraxial region concave-concave lens, and the eighth lens (L8) is a paraxial region convex-convex lens.
3. The fixed focus lens according to claim 1, wherein the first lens (L1), the second lens (L2), the third lens (L3), the fifth lens (L5), the sixth lens (L6), the seventh lens (L7), and the eighth lens (L8) are aspherical lenses;
the fourth lens (L4) is a spherical lens.
4. The prime lens according to claim 1, wherein the first lens (L1), the second lens (L2), the third lens (L3), the fifth lens (L5), the sixth lens (L6), the seventh lens (L7) and the eighth lens (L8) are plastic lenses;
the fourth lens (L4) is a glass lens.
5. The fixed focus lens according to any one of claims 1 to 4, wherein the total optical length TTL of the fixed focus lens and the back focal length BFL of the fixed focus lens satisfy the following relationship:
4.8≤TTL/BFL≤5.2。
6. the fixed focus lens as claimed in any one of claims 1 to 4, wherein the total optical length TTL of the fixed focus lens and the effective focal length F of the fixed focus lens satisfy the following relationship:
5.6≤TTL/F≤6.9。
7. the prime lens according to any one of claims 1 to 4, wherein the radius of curvature R11 of the object-side surface of the first lens (L1) and the effective focal length F of the prime lens satisfy the following relationship:
0≤F/R11≤0.2。
8. the prime lens according to any one of claims 1 to 4, wherein a distance D34 between an image side surface of the third lens (L3) and an object side surface of the fourth lens (L4) and a distance T2 between the object side surface and the image side surface of the fourth lens (L4) satisfy the following relationship:
0≤D34/T2≤0.05。
9. the prime lens according to any one of claims 1 to 4, wherein a distance D0 between the Stop (STO) and an object side surface of the fourth lens (L4) satisfies the following relationship:
D0≤0。
10. the prime lens according to any one of claims 1 to 4, wherein the sago 41 of the object-side surface of the fourth lens (L4) satisfies the following relationship:
0.45≤SAG41≤0.6。
11. the fixed focus lens according to any one of claims 1 to 4, wherein the sago 51 of the object-side surface of the fifth lens (L5) and the optically effective half aperture D1 of the fifth lens (L5) satisfy the following relationship:
-0.5≤SAG51/D1≤-0.3。
12. the prime lens according to any one of claims 1 to 4, wherein the radius of curvature R81 of the object-side surface of the eighth lens (L8), the radius of curvature R82 of the image-side surface of the eighth lens (L8), and the effective focal length F8 of the eighth lens (L8) satisfy the following relationship:
-0.35≤0.5(R81+R82)/F8≤-0.1。
13. the prime lens according to any one of claims 1 to 4, wherein a combined focal length F678 of the sixth lens (L6), the seventh lens (L7) and the eighth lens (L8) and an effective focal length F of the prime lens satisfy the following relationship:
2.1≤F678/F≤2.7。
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222249318.6U CN218158528U (en) | 2022-08-22 | 2022-08-22 | Fixed focus lens |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202222249318.6U CN218158528U (en) | 2022-08-22 | 2022-08-22 | Fixed focus lens |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117471656A (en) * | 2023-12-27 | 2024-01-30 | 江西联创电子有限公司 | Optical lens |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117471656A (en) * | 2023-12-27 | 2024-01-30 | 江西联创电子有限公司 | Optical lens |
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