Prime lens
By optimizing the combination of lens parameters and material, the ghosting problem between the image side and the object side in the fixed-focus lens is solved, and a fixed-focus lens design with high-definition imaging, ultra-large field of view and day and night confocal is realized, meeting the high requirements of automotive wide-angle lenses.
Patent Information
- Application Number
- CN202422765838.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-12
- Publication Date
- 2025-08-29
- Estimated Expiration
- 2034-11-12
AI Technical Summary
Existing fixed-focus lenses are prone to scattered ghosts between the image side and the object side, and it is difficult to take into account the requirements of imaging, compact structure and large field of view.
By optimizing the relationship between the diameter diameter, curvature radius and central axial distance of the lens, a meniscus lens and lens combination of different materials, including glass spherical and plastic aspherical lenses, combined with the design of the aperture, it meets the conditions of |D2/R2-D3/R3|+L2>1.6, and achieves the compact design and high imaging quality of the lens.
It effectively avoids scattered ghosting, realizes a fixed-focus lens with ultra-large field of view and day and night confocal, and has the characteristics of high-definition imaging and compact structure.
Smart Images
Figure CN223284450U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of optical lenses, in particular to a fixed-focus lens. Background Art
[0002] With the booming automotive industry, safe driving has become increasingly important, placing higher and higher demands on the wide-angle lenses used in these vehicles. Correcting aberrations, reducing lens head size, and improving resistance to environmental variations are all areas of research in this field. Utility Model Content
[0003] The embodiment of the utility model provides a fixed-focus lens, which can avoid the scattered point ghost images generated between the image side surface of the first lens and the object side surface of the second lens.
[0004] The embodiment of the utility model provides a fixed-focus lens, comprising 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 diameter of the image side surface of the first lens is D2, the radius of curvature of the image side surface of the first lens is R2, the diameter of the object side surface of the second lens is D3, the radius of curvature of the object side surface of the second lens is R3, and the axial distance between the image side surface of the first lens and the object side surface of the second lens is L2, satisfying:
[0006] |D2 / R2-D3 / R3|+L2>1.6.
[0007] Optionally, the optical back focus of the fixed-focus lens is BFL, the total optical length of the fixed-focus lens is TTL, and the following conditions are satisfied:
[0008] BFL / TTL>0.18.
[0009] Optionally, the first lens, the second lens and the third lens are all meniscus lenses, the object side surface of the meniscus lens is convex, and the image side surface of the meniscus lens is concave.
[0010] Optionally, the first lens is a glass spherical lens, the second lens is a plastic aspherical lens, and the third lens is a plastic aspherical lens.
[0011] Optionally, the refractive index of the first lens is Nd1, and the Abbe number of the first lens is Vd1, satisfying:
[0012] 1.6 <Nd1<2.0,27<Vd1<66。
[0013] Optionally, the fourth lens is a glass spherical lens, the fifth lens is a plastic aspherical lens, and the sixth lens is a plastic aspherical lens.
[0014] Optionally, the refractive index of the fourth lens is Nd4, and the Abbe number of the fourth lens is Vd4, satisfying:
[0015] 1.5 <Nd4<2.05,34<Vd4<95。
[0016] Optionally, the fifth lens is cemented to the sixth lens.
[0017] Optionally, a stop is further included, and the stop is located between the third lens and the fourth lens.
[0018] The present invention provides a fixed-focus lens that satisfies the following conditions: |D2 / R2-D3 / R3|+L2>1.6, thereby preventing scattered ghosting between the image-side surface of the first lens element 1 and the object-side surface of the second lens element 2. This lens also provides excellent overall performance, meeting imaging requirements, with a compact structure, an ultra-wide field of view, and day / night parfocality. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 A schematic structural diagram of a fixed-focus lens provided in Example 1 of the present utility model;
[0020] Figure 2 A spherical aberration curve diagram provided in Example 1 of the present utility model;
[0021] Figure 3 A schematic structural diagram of a fixed-focus lens provided in Example 2 of the present utility model;
[0022] Figure 4 A spherical aberration curve diagram provided in Example 2 of the present utility model;
[0023] Figure 5 This is a schematic structural diagram of a fixed-focus lens provided in Example 3 of the present utility model;
[0024] Figure 6 This is a spherical aberration curve diagram provided in Example 3 of the present utility model. DETAILED DESCRIPTION
[0025] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all of its components.
[0026] Example 1
[0027] The embodiment of the utility model provides a fixed-focus lens, Figure 1This is a structural diagram of a fixed-focus lens provided in Example 1 of the present utility model, with reference 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, which are arranged in sequence from the object side to the image side along the optical axis. The diameter of the image side surface of the first lens 1 is D2, the radius of curvature of the image side surface of the first lens 1 is R2, the diameter of the object side surface of the second lens 2 is D3, the radius of curvature of the object side surface of the second lens 2 is R3, and the axial distance between the image side surface of the first lens 1 and the object side surface of the second lens 2 is L2, satisfying:
[0028] |D2 / R2-D3 / R3|+L2>1.6. Here, || is the sign of the value.
[0029] The present invention provides a fixed-focus lens that satisfies the following conditions: |D2 / R2-D3 / R3|+L2>1.6, thereby preventing scattered ghosting between the image-side surface of the first lens element 1 and the object-side surface of the second lens element 2. This lens also provides excellent overall performance, meeting imaging requirements, with a compact structure, an ultra-wide field of view, and day / night parfocality.
[0030] Optionally, refer to Figure 1 The optical back focus of a fixed-focus lens is BFL, and the total optical length of the fixed-focus lens is TTL, which satisfies the following conditions: BFL / TTL > 0.18. The optical back focus of a fixed-focus lens refers to the distance from the vertex of the last optical surface of the fixed-focus lens to the image plane IMA. When BFL / TTL > 0.18, sufficient space is ensured for the installation of the imaging sensor and the filter CG.
[0031] Optionally, refer to Figure 1 , the first lens 1, the second lens 2 and the third lens 3 are all meniscus lenses, the object side surface of the meniscus lens is convex, and the image side surface of the meniscus lens is concave. The object side surface of the first lens 1 is convex, and the image side surface of the first lens 1 is concave. The object side surface of the second lens 2 is convex, and the image side surface of the second lens 2 is concave. The object side surface of the third lens 3 is convex, and the image side surface of the third lens 3 is concave. Allowing light at a large angle to enter the fixed-focus lens is conducive to the realization of an ultra-large field of view, allowing light to be stable during propagation, without excessive deflection on a certain surface, so as to avoid introducing larger aberrations. At the same time, it is conducive to reducing the aperture and total length of the fixed-focus lens.
[0032] Optionally, refer to Figure 1 The first lens 1 is a glass spherical lens, the second lens 2 is a plastic aspherical lens, and the third lens 3 is a plastic aspherical lens.
[0033] Optionally, refer to Figure 1, the refractive index of the first lens 1 is Nd1, and the Abbe number of the first lens 1 is Vd1, satisfying: 1.6 < Nd1 < 2.0, 27 < Vd1 < 66. When the refractive index and Abbe number of the first lens 1 are within this range, light can be better converged, the ratio of the lens aperture to the radius of curvature can be reduced, and the marginal illumination can be improved.
[0034] Optionally, refer to Figure 1 , the fourth lens 4 is a glass spherical lens, the fifth lens 5 is a plastic aspherical lens, and the sixth lens 6 is a plastic aspherical lens. In the embodiment of the present invention, a combination of 2 spherical glasses and 4 aspherical plastics can well correct aberration, ensure good enough image quality, simultaneously meet day and night confocal and a large field angle, the total length of the lens is less than 18.3 mm, the image plane diameter can reach 6.9 mm, and the FOV can reach 160°.
[0035] Optionally, refer to Figure 1 , the refractive index of the fourth lens 4 is Nd4, and the Abbe number of the fourth lens 4 is Vd4, satisfying: 1.5 < Nd4 < 2.05, 34 < Vd4 < 95. The fourth lens 4 plays a role in correcting defocus at high and low temperatures and infrared defocus, and配合 the optical power of other lenses, which is beneficial to achieving day and night confocal.
[0036] Optionally, refer to Figure 1 , the fifth lens 5 and the sixth lens 6 are glued together, which is beneficial to reducing the tolerance sensitivity and is also beneficial to correcting the field curvature of the fixed-focus lens, thereby obtaining a high-definition image quality.
[0037] Optionally, refer to Figure 1 , the fixed-focus lens further includes an aperture STO, and the aperture STO is located between the third lens 3 and the fourth lens 4. The fixed-focus lens includes a first lens 1, a second lens 2, a third lens 3, an aperture STO, a fourth lens 4, a fifth lens 5, and a sixth lens 6 arranged in sequence along the optical axis from the object side to the image side.
[0038] In one embodiment, the fifth lens 5 and the sixth lens 6 are plastic aspherical lenses, and one is made of a high refractive index material and the other is made of a low refractive index material. By matching the refractive indices of the fifth lens 5 and the sixth lens 6, it is beneficial to chromatic aberration correction, further reducing the aberration of the fixed-focus lens and facilitating the achievement of high-definition image quality. For example, the refractive index of the fifth lens 5 is greater than the refractive index of the sixth lens 6.
[0039] Exemplarily, refer to Figure 1 , the fixed-focus lens further includes a filter CG, and the filter CG is located on one side of the image side surface of the sixth lens 6. The filter CG is located on the side of the sixth lens 6 away from the first lens 1.
[0040] By rationally allocating parameters such as the material, optical power, center thickness of each lens, and on-axis spacing between lenses, the above-mentioned fixed-focus lens can achieve at least one of the following beneficial effects: excellent imaging, compact structure, day and night confocality, and a large field of view.
[0041] Table 1: Design values of the fixed-focus lens in Example 1
[0042] Surface number Face shape Radius of curvature thickness Refractive index Abbe number Semi-caliber S1 spherical surface 26.954 0.766 1.98 65.00 6.514 S2 spherical surface 5.321 0.607 4.430 S3 Aspheric 12.575 1.981 1.58 60.00 4.140 S4 Aspheric 2.183 3.124 2.576 S5 spherical surface PL -0.750 2.300 S6 Aspheric 3.144 2.493 1.58 30.75 2.203 S7 Aspheric 5.491 0.725 1.238 STO spherical surface PL 0.128 0.999 S9 spherical surface 11.748 2.140 1.55 93.11 2.500 S10 spherical surface -3.092 -0.316 2.500 S11 spherical surface PL 0.716 1.650 S12 Aspheric -269.297 0.703 1.64 24.11 1.909 S13 Aspheric 2.482 2.244 1.52 60.00 2.317 S14 Aspheric -2.654 2.000 2.526 S15 spherical surface PL 0.700 1.52 64.20 3.206 S16 spherical surface PL 0.860 3.308 IMA spherical surface PL 0 3.500
[0043] Table 1 shows a design value of the fixed focus lens in Example 1. The specific value can be adjusted according to product requirements and is not a limitation to the embodiment of the present invention. Figure 1 As shown in . A lens generally includes two surfaces, each of which 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 (i.e., the object side), the surface number "S2" represents the back surface of the first lens 1 (i.e., the image side), and so on, which will not be repeated here. It should be noted that "IMA" in the "Surface Number" column represents the image surface of the fixed-focus lens. "STO" represents the aperture. 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 side of the surface close to the image side, that is, a positive value represents that the surface is bent toward the image surface IMA side; a negative radius of curvature value represents that the center of curvature is on the side of the surface away from the image side, that is, a negative value represents that the surface is bent toward the object side. "PL" in the "Curvature Radius" column indicates that the surface is a plane and the radius of curvature is infinite. The value in the "Thickness" column represents the central axial distance from the current surface to the next surface. The "Refractive Index" column indicates the refractive index of the medium between the current and next surfaces, representing the material's ability to deflect light. Empty spaces in the "Refractive Index" column represent the refractive index of air, which is 1. The Abbe number represents the dispersion properties of light between the current and next surfaces; an empty space indicates that the current position is air. The value in the "Half-Aperture" column indicates the half-height of light at the current surface, expressed in mm.
[0044] Because the number of digits in each parameter's value varies, resulting in focus errors, the thickness corresponding to the row of surface number S16 can vary slightly. Adjust the value as needed to achieve clear focus. Surface numbers "S5" and "S11" are light-blocking surfaces. A semi-aperture setting and vignetting are set on these surfaces to block excess light and ensure resolution.
[0045] Table 2 A design value of the aspheric coefficient of the lens in the fixed-focus lens in Example 1
[0046]
[0047] Table 2 shows a design value of the aspheric coefficient of the lens in the fixed-focus lens of Example 1. The specific value can be adjusted according to product requirements and is not a limitation to the embodiment of the present invention. The fixed-focus lens shown in Table 2 can be Figure 1 The meaning of the column "surface number" in Table 2 is consistent with that of the column "surface number" in Table 1. "E" in each embodiment of the present invention represents an index with base 10.
[0048] Optionally, the surface of the aspheric lens satisfies the formula:
[0049]
[0050] In the equation, Z is the sagittal height of the aspheric surface, c is the basic curvature at the vertex, k is the conic constant, r is the radial coordinate perpendicular to the optical axis, and a is the radius of the aspheric surface. i is the coefficient of the higher-order term, a i r 2i is a high-order term of the aspheric surface. i is a positive integer from 2 to 7.
[0051] For example, in Example 1, the focal length f of the fixed-focus lens is 1.768 mm, and the field of view is 159.42°. Nd1 = 1.98, Vd1 = 65.00, Nd4 = 1.55, and Vd4 = 93.11. |D2 / R2-D3 / R3| + L2 = 1.614. BFL / TTL = 0.196.
[0052] Figure 2 A spherical aberration curve diagram provided in Example 1 of the present utility model, referring to Figure 2 , the vertical direction represents the normalization of the aperture, 0 represents the optical axis, the vertical vertex represents the maximum pupil radius; the horizontal direction represents the offset relative to the ideal focus, in millimeters (mm). The different linear curves in the figure represent different wavelengths of system imaging, which are represented by Figure 2 It can be seen that the axial aberrations at different wavelengths are all controlled within the range of (-0.05mm, +0.05mm), indicating that the spherical aberration of this fixed-focus lens at each wavelength is well controlled and can meet the requirements of day and night confocality.
[0053] Example 2
[0054] Similarities with the above embodiment are not repeated here.
[0055] Table 3: Design values of the fixed-focus lens in Example 2
[0056] Surface number Face shape Radius of curvature thickness Refractive index Abbe number Semi-caliber S1 spherical surface 17.589 0.699 1.87 28.04 6.687 S2 spherical surface 4.223 1.792 4.012 S3 Aspheric 5.054 0.892 1.68 48.06 3.437 S4 Aspheric 2.237 3.097 2.619 S5 spherical surface PL -0.750 2.300 S6 Aspheric 3.604 2.830 1.69 18.00 2.271 S7 Aspheric 5.339 0.780 1.174 STO spherical surface PL 0.128 0.984 S9 spherical surface 18.381 2.272 1.80 36.30 2.500 S10 spherical surface -3.662 -0.216 2.500 S11 spherical surface PL 0.221 1.650 S12 Aspheric -15.248 0.813 1.58 18.00 1.716 S13 Aspheric 2.577 2.248 1.50 72.00 2.260 S14 Aspheric -2.811 2.000 2.456 S15 spherical surface PL 0.700 1.52 64.20 3.154 S16 spherical surface PL 0.821 3.263 IMA spherical surface PL 0.000 3.459
[0057] Table 3 shows a design value of the fixed focus lens in Example 2. The specific value can be adjusted according to product requirements and is not a limitation to the embodiment of the present invention. Figure 3 As shown in .
[0058] Table 4: A design value of the aspheric coefficient of the lens in the fixed-focus lens in Example 2
[0059]
[0060] Table 4 shows a design value of the aspheric coefficient of the lens in the fixed-focus lens of Example 2. The specific value can be adjusted according to product requirements and is not a limitation to the embodiment of the present invention. The fixed-focus lens shown in Table 4 can be Figure 3 As shown in .
[0061] For example, in Example 2, the focal length f of the fixed-focus lens is 1.718 mm, and the field of view is 159.48°. Nd1 = 1.87, Vd1 = 28.04, Nd4 = 1.80, and Vd4 = 36.30. |D2 / R2 - D3 / R3| + L2 = 2.332. BFL / TTL = 0.192.
[0062] Example 3
[0063] Similarities with the above embodiment are not repeated here.
[0064] Table 5: Design values of the fixed-focus lens in Example 3
[0065] Surface number Face shape Radius of curvature thickness Refractive index Abbe number Semi-caliber S1 spherical surface 13.358 0.837 1.65 30.00 8.259 S2 spherical surface 4.670 1.540 4.614 S3 Aspheric 3.596 0.700 1.69 60.00 4.535 S4 Aspheric 1.811 4.118 2.961 S5 spherical surface PL -0.750 2.650 S6 Aspheric 3.782 3.000 1.52 18.00 2.561 S7 Aspheric 3.988 1.153 1.410 STO spherical surface PL 0.128 1.137 S9 spherical surface 5.583 1.678 2.01 34.90 2.500 S10 spherical surface -6.661 -0.216 2.500 S11 spherical surface PL 0.221 1.650 S12 Aspheric -20.403 0.699 1.64 18.00 1.689 S13 Aspheric 2.713 1.680 1.50 60.00 1.924 S14 Aspheric -4.180 2.000 2.095 S15 spherical surface PL 0.700 1.52 64.20 3.013 S16 spherical surface PL 0.743 3.187 IMA spherical surface PL 0.000 3.478
[0066] Table 5 shows a design value of the fixed focus lens in Example 3. The specific value can be adjusted according to product requirements and is not a limitation to the embodiments of the present invention. Figure 5 As shown in .
[0067] Table 6 A design value of the aspheric coefficient of the lens in the fixed focus lens of Example 3
[0068]
[0069] Table 6 shows a design value of the aspheric coefficient of the lens in the fixed-focus lens of Example 3. The specific value can be adjusted according to product requirements and is not a limitation to the embodiments of the present invention. The fixed-focus lens shown in Table 6 can be Figure 5 As shown in .
[0070] For example, in Example 3, the focal length f of the fixed-focus lens is 1.934 mm, and the field of view is 159.32°. Nd1 = 1.65, Vd1 = 30.00, Nd4 = 2.01, and Vd4 = 34.90. |D2 / R2 - D3 / R3| + L2 = 2.087. BFL / TTL = 0.189.
[0071] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations, and substitutions are possible for those skilled in the art without departing from the scope of protection 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 and may include many other equivalent embodiments without departing from the scope of the present invention. The scope of the present invention is determined by the scope of the appended claims.
Claims
1. A fixed-focus lens, characterized in that: comprising 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 diameter of the image side surface of the first lens is D2, the radius of curvature of the image side surface of the first lens is R2, the diameter of the object side surface of the second lens is D3, the radius of curvature of the object side surface of the second lens is R3, and the axial distance between the image side surface of the first lens and the object side surface of the second lens is L2, satisfying: |D2 / R2-D3 / R3|+L2>1.
6.
2. The fixed-focus lens according to claim 1, wherein: The optical back focus of the fixed-focus lens is BFL, the total optical length of the fixed-focus lens is TTL, and the following conditions are met: BFL / TTL>0.
18.
3. The fixed-focus lens according to claim 1, wherein: The first lens, the second lens and the third lens are all meniscus lenses, the object side surface of the meniscus lens is convex, and the image side surface of the meniscus lens is concave.
4. The fixed-focus lens according to claim 3, wherein: The first lens is a glass spherical lens, the second lens is a plastic aspherical lens, and the third lens is a plastic aspherical lens.
5. The fixed-focus lens according to claim 3, wherein: The refractive index of the first lens is Nd1, and the Abbe number of the first lens is Vd1, which satisfies: 1.6 <Nd1<2.0,27<Vd1<66。 6. The fixed-focus lens according to claim 1, wherein: The fourth lens is a glass spherical lens, the fifth lens is a plastic aspherical lens, and the sixth lens is a plastic aspherical lens.
7. The fixed-focus lens according to claim 6, wherein: The refractive index of the fourth lens is Nd4, and the Abbe number of the fourth lens is Vd4, which satisfies: 1.5 <Nd4<2.05,34<Vd4<95。 8. The fixed-focus lens according to claim 6, wherein: The fifth lens is cemented to the sixth lens.
9. The fixed-focus lens according to claim 1, wherein: The optical system further includes a stop located between the third lens and the fourth lens.