Prime lens
By designing a multi-lens combination in a wide-angle lens in a car, combining meniscus and aspherical lenses, and combining them with a aperture, the problems of aberration and large lens size are solved, and the determination of high imaging, compact structure and large field of view is achieved. The focal lens meets the needs of day and night confocal.
Patent Information
- Application Number
- CN202411606392.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-12
- Publication Date
- 2025-01-03
AI Technical Summary
Existing prime lenses are difficult to effectively correct aberrations in automotive wide-angle lenses, and the lens head size is large, which cannot meet the needs of day and night environmental variation.
A fixed-focus lens is designed, through a plurality of lenses arranged in sequence from object to image along the optical axis, including a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, Combining meniscus lenses, glass spherical lenses and plastic aspherical lenses, meet specific radius of curvature, refractive index and Abbe number ranges, the combination is made using a diaphragm to ensure that |D2/R2-D3/R3|+L2>1.6 to Avoid scattered ghosting and achieve super large field of view and day and night confocal.
It achieves comprehensive performance of high imaging requirements, compact structure, ultra-large field of view angle and day and night confocal performance, avoids aberrations and ghosts, meets the high requirements of automotive wide-angle lenses, and reduces lens size and aberrations.
Smart Images
Figure CN119247595A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of optical lenses, and in particular to a fixed-focus lens. Background Art
[0002] With the booming development of the automotive industry, safe driving has become increasingly important, and higher and higher requirements have been placed on the wide-angle lenses it carries. How to correct aberrations, reduce the size of the lens head, and be more resistant to environmental changes are all areas that need to be studied in this field. Summary of the invention
[0003] The embodiment of the present invention provides a fixed-focus lens, which can avoid scattered point ghosts generated between the image side surface of a first lens and the object side surface of a second lens.
[0004] An embodiment of the present invention 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 an 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 central axial distance from the image side surface of the first lens to 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, and the total optical length of the fixed-focus lens is TTL, which satisfies:
[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 lenses is a convex surface, and the image side surface of the meniscus lenses is a concave surface.
[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, which satisfies:
[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, which satisfies:
[0015] 1.5 <Nd4<2.05,34<Vd4<95。
[0016] Optionally, the fifth lens is glued 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 embodiment of the present invention provides a fixed-focus lens, which satisfies: |D2 / R2-D3 / R3|+L2>1.6, and can avoid the scattered point ghosts generated between the image side surface of the first lens 1 and the object side surface of the second lens 2. Provided is a fixed-focus lens with excellent comprehensive performance that takes into account imaging requirements, compact structure, ultra-large field angle, and day and night confocality. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 A schematic structural diagram of a fixed-focus lens provided in Embodiment 1 of the present invention;
[0020] Figure 2 A spherical aberration curve diagram provided in Example 1 of the present invention;
[0021] Figure 3 A schematic structural diagram of a fixed-focus lens provided in Embodiment 2 of the present invention;
[0022] Figure 4 A spherical aberration curve diagram provided in Embodiment 2 of the present invention;
[0023] Figure 5 A schematic structural diagram of a fixed-focus lens provided in Embodiment 3 of the present invention;
[0024] Figure 6 A spherical aberration curve diagram provided in Example 3 of the present invention. DETAILED DESCRIPTION
[0025] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.
[0026] Embodiment 1
[0027] An embodiment of the present invention provides a fixed-focus lens. Figure 1 This is a schematic diagram of the structure of a fixed-focus lens provided in Embodiment 1 of the present invention, referring to Figure 1, the fixed focus lens comprises 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. 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 central axial distance from the image side surface of the first lens 1 to the object side surface of the second lens 2 is L2, satisfying:
[0028] |D2 / R2-D3 / R3|+L2>1.6. Wherein, || is the sign of the value.
[0029] The embodiment of the present invention provides a fixed-focus lens, which satisfies: |D2 / R2-D3 / R3|+L2>1.6, and can avoid the scattered point ghosts generated between the image side surface of the first lens 1 and the object side surface of the second lens 2. Provided is a fixed-focus lens with excellent comprehensive performance that takes into account imaging requirements, compact structure, ultra-large field angle, and day and night confocality.
[0030] Optionally, refer to Figure 1 , the optical back focus of the fixed-focus lens is BFL, and the total optical length of the fixed-focus lens is TTL, which satisfies: BFL / TTL>0.18. Among them, the optical back focus of the 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 is met, it can ensure that there is enough installation space for 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 the light to be stable during propagation, without excessive deflection on a certain surface, so as to avoid introducing greater 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 peripheral illumination can be improved.
[0034] Optionally, referring 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 aberrations, ensure good enough image quality, can simultaneously meet day and night confocal and a large field of view 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, referring 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 in cooperation with the optical power of other lenses, is conducive to achieving day and night confocal.
[0036] Optionally, referring to Figure 1 , the fifth lens 5 and the sixth lens 6 are glued together, which is conducive to reducing the tolerance sensitivity and is also conducive to correcting the field curvature of the fixed-focus lens, thereby obtaining a high-definition image quality.
[0037] Optionally, referring to Figure 1 , the fixed-focus lens further includes a diaphragm STO, and the diaphragm 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, a diaphragm 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 conducive to chromatic aberration correction, further reducing the aberrations 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 that of the sixth lens 6.
[0039] Exemplarily, referring 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 reasonably allocating parameters such as the material, optical focal length, center thickness of each lens, and axial spacing between lenses, the above-mentioned fixed-focus lens can achieve at least one beneficial effect such as excellent imaging, compact structure, day and night confocality, and a large field of view.
[0041] Table 1 A design value of the fixed focus lens in Example 1
[0042] Surface number Face type Radius of curvature thickness Refractive Index Abbe number Semi-caliber S1 Spherical 26.954 0.766 1.98 65.00 6.514 S2 Spherical 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 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 PL 0.128 0.999 S9 Spherical 11.748 2.140 1.55 93.11 2.500 S10 Spherical -3.092 -0.316 2.500 S11 Spherical 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 PL 0.700 1.52 64.20 3.206 S16 Spherical PL 0.860 3.308 IMA Spherical PL 0 3.500
[0043] Table 1 shows a design value of the fixed-focus lens in Example 1, and its specific value can be adjusted according to product requirements and is not a limitation of the embodiment 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, 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 side IMA; 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. The "PL" in the "Radius of Curvature" column represents 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 surface and the next surface, representing the ability of the material between the current surface and the next surface to deflect light. The blank in the "Refractive Index" column is the refractive index of air, which is 1. The Abbe number represents the dispersion characteristics of the material between the current surface and the next surface for light, and the blank represents that the current position is air. The value in the "Half-Aperture" column indicates the corresponding half-height of the light on the current surface, in mm.
[0044] Among them, due to the different digits of each parameter value, there is an error in focus, so the thickness corresponding to the line of surface number S16 can vary slightly, and the value can be adjusted according to the situation to achieve the purpose of clear focus. The two planes with surface numbers "S5" and "S11" are light blocking surfaces. Half-apertures and vignetting are set on these two light blocking 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 in Example 1. The specific value can be adjusted according to product requirements and is not a limitation of 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] Among them, 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 in the direction perpendicular to the optical axis, and a 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.
[0050] For example, in the first embodiment, the focal length f of the fixed-focus lens is 1.768 mm, and the field of view angle is 159.42°. Nd1=1.98, Vd1=65.00, Nd4=1.55, Vd4=93.11. |D2 / R2-D3 / R3|+L2=1.614. BFL / TTL=0.196.
[0051] Figure 2 A spherical aberration curve diagram provided in Example 1 of the present invention, 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 day and night confocal requirements.
[0052] Embodiment 2
[0053] The similarities with the above-mentioned embodiment are not repeated here.
[0054] Table 3 A design value of the fixed focus lens in Example 2
[0055] Surface number Face type Radius of curvature thickness Refractive Index Abbe number Semi-caliber S1 Spherical 17.589 0.699 1.87 28.04 6.687 S2 Spherical 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 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 PL 0.128 0.984 S9 Spherical 18.381 2.272 1.80 36.30 2.500 S10 Spherical -3.662 -0.216 2.500 S11 Spherical 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 PL 0.700 1.52 64.20 3.154 S16 Spherical PL 0.821 3.263 IMA Spherical PL 0.000 3.459
[0056] Table 3 shows a design value of the fixed-focus lens in Example 2, and its specific value can be adjusted according to product requirements and is not a limitation of the embodiment of the present invention. The fixed-focus lens shown in Table 3 can be Figure 3as shown in .
[0057] Table 4 A design value of the aspheric coefficient of the lens in the fixed focus lens in Example 2
[0058]
[0059] Table 4 shows a design value of the aspheric coefficient of the lens in the fixed-focus lens in Example 2. The specific value can be adjusted according to product requirements and is not a limitation of the embodiment of the present invention. The fixed-focus lens shown in Table 4 can be Figure 3 as shown in .
[0060] For example, in the second embodiment, the focal length f of the fixed-focus lens is 1.718 mm, and the field of view angle is 159.48°. Nd1=1.87, Vd1=28.04, Nd4=1.80, Vd4=36.30. |D2 / R2-D3 / R3|+L2=2.332. BFL / TTL=0.192.
[0061] Embodiment 3
[0062] The similarities with the above-mentioned embodiment are not repeated here.
[0063] Table 5 A design value of the fixed focus lens in Example 3
[0064] Surface number Face type Radius of curvature thickness Refractive Index Abbe number Semi-caliber S1 Spherical 13.358 0.837 1.65 30.00 8.259 S2 Spherical 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 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 PL 0.128 1.137 S9 Spherical 5.583 1.678 2.01 34.90 2.500 S10 Spherical -6.661 -0.216 2.500 S11 Spherical 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 PL 0.700 1.52 64.20 3.013 S16 Spherical PL 0.743 3.187 IMA Spherical PL 0.000 3.478
[0065] Table 5 shows a design value of the fixed-focus lens in Example 3, and its specific value can be adjusted according to product requirements and is not a limitation of the embodiment of the present invention. The fixed-focus lens shown in Table 5 can be Figure 5 as shown in .
[0066] Table 6 A design value of the aspheric coefficient of the lens in the fixed focus lens in Example 3
[0067]
[0068] Table 6 shows a design value of the aspheric coefficient of the lens in the fixed-focus lens in Example 3. The specific value can be adjusted according to product requirements and is not a limitation of the embodiment of the present invention. The fixed-focus lens shown in Table 6 can be Figure 5 as shown in .
[0069] For example, in the third embodiment, the focal length f of the fixed-focus lens is 1.934 mm, and the field of view angle is 159.32°. Nd1=1.65, Vd1=30.00, Nd4=2.01, Vd4=34.90. |D2 / R2-D3 / R3|+L2=2.087. BFL / TTL=0.189.
[0070] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations and substitutions can be made by 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 more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, 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 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 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 central axial distance from the image side surface of the first lens to 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, characterized in that: The optical back focus of the fixed-focus lens is BFL, and the total optical length of the fixed-focus lens is TTL, which satisfies: BFL / TTL>0.
18.
3. The fixed-focus lens according to claim 1, characterized in that: The first lens, the second lens and the third lens are all meniscus lenses, the object side surface of the meniscus lens is a convex surface, and the image side surface of the meniscus lens is a concave surface.
4. The fixed-focus lens according to claim 3, characterized in that: 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, characterized in that: 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: Also included is an aperture stop located between the third lens and the fourth lens.