CN210626760U - Lens - Google Patents
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- CN210626760U CN210626760U CN201921363677.6U CN201921363677U CN210626760U CN 210626760 U CN210626760 U CN 210626760U CN 201921363677 U CN201921363677 U CN 201921363677U CN 210626760 U CN210626760 U CN 210626760U
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Abstract
The utility model discloses a lens, the lens includes first negative focal power lens, second negative focal power lens, first positive focal power lens, second positive focal power lens, third negative focal power lens, third positive focal power lens and the imaging surface that arrange by thing side to picture side in proper order; the lens satisfies the following conditions: f 2/f' is not less than-2.8 and not more than-2.0; f 4/f' is more than or equal to 0.8 and less than or equal to 1.4; f 5/f' is more than or equal to 1.0 and less than or equal to 1.6; wherein f2 is the focal length of the second negative power lens, f4 is the focal length of the second positive power lens, f5 is the focal length of the third negative power lens, and f' is the focal length of the lens. Since the lenses are sequentially arranged from the object side to the image side in a specific order in the lens in the embodiment of the present invention, and the lenses in the lens satisfy specific conditions, the present invention provides a large-aperture athermal differential wave-plastic hybrid prime lens.
Description
Technical Field
The utility model relates to an optical imaging technical field especially relates to a camera lens.
Background
With social progress, the requirements of people on video monitoring cameras are increasingly improved, and currently, the monitoring fixed focus lens is widely applied to daily life of people, but the conventional security monitoring lens has the following defects:
most of the full-glass lens apertures are below F2.0, and the noise is large under the condition of low ambient illumination at night, so that the definition is influenced; the full-glass prime lens with a large aperture (the aperture is larger than F1.6) is often large in size (the total lens length TTL exceeds 24mm), and the cost is high; the range of optical characteristics such as refractive index of glass lens material is small along with the temperature change, so the back focus changing ability of the camera caused by the temperature influence is weak. Therefore, it is particularly important to develop a large-aperture athermal wave-plastic mixed fixed-focus lens.
SUMMERY OF THE UTILITY MODEL
The embodiment of the utility model provides a camera lens for a big light ring heat dissipation is poor ripples and is moulded and is mixed tight shot is provided.
An embodiment of the present invention provides a lens assembly, which includes a first negative power lens, a second negative power lens, a first positive power lens, a second positive power lens, a third negative power lens, a third positive power lens and an image plane sequentially arranged from an object side to an image side;
the lens satisfies the following conditions:
-2.8≤f2/f’≤-2.0；
0.8≤f4/f’≤1.4；
1.0≤f5/f’≤1.6；
wherein f2 is the focal length of the second negative power lens, f4 is the focal length of the second positive power lens, f5 is the focal length of the third negative power lens, and f' is the focal length of the lens.
Further, the first negative power lens includes a meniscus lens, and a surface thereof facing the object side is convex.
Further, the second negative power lens includes a plastic aspheric lens, and a surface of the plastic aspheric lens facing the object side is a concave surface.
Further, the second positive power lens includes a plastic aspheric lens, which is a biconvex lens.
Further, the third negative power lens includes a plastic aspheric lens, and a surface of the plastic aspheric lens facing the object side is a concave surface.
Further, the first positive power lens and the third positive power lens include a double convex lens.
Further, the refractive index of the second negative power lens is 1.55 or less; the refractive index of the third negative-power lens is 1.62 or more.
Further, the abbe number of the second negative power lens is 55 or more; the abbe number of the first positive focal power lens is more than or equal to 65; the third negative-power lens has an abbe number of 25 or less.
Further, a diaphragm is arranged between the second negative-power lens and the first positive-power lens.
Further, a color filter is disposed between the third positive power lens and the imaging surface.
An embodiment of the present invention provides a lens assembly, which includes a first negative power lens, a second negative power lens, a first positive power lens, a second positive power lens, a third negative power lens, a third positive power lens and an image plane sequentially arranged from an object side to an image side; the lens satisfies the following conditions: f 2/f' is not less than-2.8 and not more than-2.0; f 4/f' is more than or equal to 0.8 and less than or equal to 1.4; f 5/f' is more than or equal to 1.0 and less than or equal to 1.6; wherein f2 is the focal length of the second negative power lens, f4 is the focal length of the second positive power lens, f5 is the focal length of the third negative power lens, and f' is the focal length of the lens. In the embodiment of the present invention, the lenses are arranged in the lens from the object side to the image side in a specific order, and the lenses in the lens satisfy the condition-2.8 ≦ f2/f ≦ -2.0; f 4/f' is more than or equal to 0.8 and less than or equal to 1.4; f 5/f' is more than or equal to 1.0 and less than or equal to 1.6, therefore the utility model provides a lens is big light ring heat dissipation difference ripples and plastics mixture tight shot.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic view of a lens structure provided in an embodiment of the present invention;
fig. 2 is a graph of an optical transfer function (MTF) of the lens in a normal temperature state in a visible light band according to an embodiment of the present invention;
fig. 3 is a graph of an optical transfer function (MTF) of the lens provided by the embodiment of the present invention at a visible light band of-30 ℃;
fig. 4 is a graph of an optical transfer function (MTF) of the lens provided in the embodiment of the present invention in a state of a visible light band +70 ℃;
fig. 5 is a graph of an optical transfer function (MTF) of the lens in an infrared band normal temperature state according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the attached drawings, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.
Fig. 1 is a schematic structural diagram of a lens barrel according to an embodiment of the present invention, the lens barrel includes a first negative power lens L1, a second negative power lens L2, a first positive power lens L3, a second positive power lens L4, a third negative power lens L5, a third positive power lens L6, and an image plane N, which are sequentially arranged from an object side to an image side;
the lens satisfies the following conditions:
-2.8≤f2/f’≤-2.0；
0.8≤f4/f’≤1.4；
1.0≤f5/f’≤1.6；
wherein f2 is the focal length of the second negative power lens, f4 is the focal length of the second positive power lens, f5 is the focal length of the third negative power lens, and f' is the focal length of the lens.
The embodiment of the utility model provides an every lens in the camera lens have its focus f that corresponds, and wherein, the focus of second negative power lens is f2, and the focus of second positive power lens is f4, and the focus of third negative power lens is f5, and the focus of camera lens is f'. The focal length of the lens meets the relation that f 2/f' is more than or equal to-2.8 and less than or equal to-2.0; f 4/f' is more than or equal to 0.8 and less than or equal to 1.4; f 5/f' is not less than 1.0 and not more than 1.6. In the embodiment of the present invention, the lenses are arranged in the lens from the object side to the image side in a specific order, and the lenses in the lens satisfy the condition-2.8 ≦ f2/f ≦ -2.0; f 4/f' is more than or equal to 0.8 and less than or equal to 1.4; f 5/f' is more than or equal to 1.0 and less than or equal to 1.6, therefore the utility model provides a lens is big light ring heat dissipation difference ripples and plastics mixture tight shot.
In order to improve the imaging quality of the lens, the first negative power lens comprises a meniscus lens, and the surface of the meniscus lens, which faces the object side, is convex. The second negative power lens comprises a plastic aspheric lens, and the surface of the plastic aspheric lens facing the object side is a concave surface. The second positive focal power lens comprises a plastic aspheric lens which is a biconvex lens. The third negative power lens comprises a plastic aspheric lens, and the surface of the plastic aspheric lens facing the object side is a concave surface. The first and third positive power lenses comprise double convex lenses.
In order to improve the refractive index of the lens and reduce the total length of the lens, the refractive index of the second negative-power lens is less than or equal to 1.55; the refractive index of the third negative-power lens is 1.62 or more. For example, the refractive index Nd2 of the second negative power lens is 1.55, 1.40, or the like, and the refractive index Nd5 of the third negative power lens is 1.62, 1.70, or the like.
In addition, when light rays of a spherical lens enter the lens and then reach a focal plane, serious refraction and bending are easy to occur at the edge part of the spherical lens than at the central part of the spherical lens, and the phenomenon can cause the reduction of sharpness and contrast and the generation of light spots, thereby causing the reduction of image quality. And such aberrations are called spherical aberrations. In the embodiment of the present invention, the refractive index of the second negative power lens is less than or equal to 1.55, and the refractive index of the third negative power lens is greater than or equal to 1.62, which can also reduce spherical aberration and improve image quality. Moreover, the refractive index of the second negative focal power lens is less than or equal to 1.55, and the refractive index of the third negative focal power lens is greater than or equal to 1.62, so that the resolution of the lens can be improved, and the total length of the lens can be reduced.
In order to realize day and night confocal and athermalization in the full focal section of the lens and enable clear imaging, in the embodiment of the present invention, the abbe number of the second negative power lens is greater than or equal to 55; the abbe number of the first positive focal power lens is more than or equal to 65; the third negative-power lens has an abbe number of 25 or less. In addition, the abbe number of the second negative power lens is 55 or more; the abbe number of the first positive focal power lens is more than or equal to 65; the abbe number of the third negative-power lens is less than or equal to 25, and the chromatic aberration of the image can be reduced, so that the image quality is improved.
In an embodiment of the present invention, a diaphragm P is disposed between the second negative power lens and the first positive power lens. The diaphragm comprises an aperture diaphragm, the aperture size of the aperture diaphragm determines the aperture value of the system and the depth of field during shooting, the aperture size can be fixed, or the aperture diaphragm with adjustable aperture can be placed according to requirements to realize the adjustment of the clear aperture, namely the purposes of changing the aperture value of the system and changing the depth of field are achieved.
And a color filter M is arranged between the third positive focal power lens and the imaging surface. Filters are optical devices used to select a desired wavelength band of radiation.
The utility model adopts the structure, a high resolution fixed focus imaging system that big light ring, heat dissipation are poor, ripples are moulded and are mixed has been realized. Adopting 6 optical lenses with specific structural shapes, arranging the optical lenses in sequence from the object side to the image side according to a specific sequence, and enabling parameters such as refractive index, Abbe coefficient and the like of the optical lenses to be matched with imaging conditions through distribution of the optical power of each optical lens; therefore, on the premise of larger image surface, the large aperture, low cost, miniaturization and high resolution are simultaneously met, and further better low-light imaging performance, better color reducibility and better environmental adaptability are realized; the method can be widely applied to the field of security monitoring.
The embodiment of the utility model provides a camera lens light ring reaches F1.6, and under the low light level environment, the noise is littleer, and the definition is better. The total lens length TTL is less than 23.6mm, the volume limitation of most monitoring cameras on the market can be met, and the universality is higher. The design of eliminating heat difference is carried out, and the problem of virtual coke caused by expansion with heat and contraction with cold due to temperature change is compensated. The design of the wave-plastic mixed version is adopted, the cost is lower, the performance is better, and the cost performance of the product is improved.
The following is an example of the lens parameters provided by the embodiments of the present invention.
Example 1:
in a specific implementation, the radius of curvature R, the center thickness Tc, the refractive index Nd, and the abbe constant Vd of each lens of the imaging system satisfy the conditions listed in table 1:
TABLE 1
Wherein, the 3 rd, 4 th, 7 th, 8 th, 9 th, 10 th corresponding aspheric surface can be expressed by the relation between the rise Z and the caliber Y, R value, the cone coefficient K, the multiple term coefficients A4, A6, A8, A10, A12, A14 and A16:
Z＝[(1/R)2·Y]/1+[1-(1+k)(1/R)2·Y2]1/2+A4Y4+A6Y6+A8Y8+A10Y10+A12Y12+A14Y14+A16Y16。
coefficient of the 3 rd plane:
K＝-3.3576479；A4＝-0.0093650322；A6＝0.0022794361；A8＝-0.000315935；A10＝1.8799834e-005；A12＝0；A14＝0；A16＝0。
coefficient of the 4 th plane:
K＝-1.9540314；A4＝0.0035036416；A6＝0.00013841051；A8＝-3.8859332e-005；A10＝3.7857465e-006；A12＝-1.4546119e-007；A14＝0；A16＝0。
coefficient of the 7 th plane:
K＝0.0254193；A4＝0.0014551641；A6＝-0.00017754785；A8＝1.0768624e-005；A10＝-4.6030778e-007；A12＝2.8395994e-009；A14＝0；A16＝0。
coefficient of the 8 th plane:
K＝0.3731523；A4＝0.0044060625；A6＝2.7222094e-005；A8＝3.0198271e-006；A10＝-8.0128934e-007；A12＝4.6128206e-008；A14＝0；A16＝0。
coefficient of the 9 th plane:
K＝-2.9303524；A4＝0.0089587616；A6＝-0.0010258542；A8＝6.7655462e-005；A10＝-3.8805451e-006；A12＝1.1752484e-007；A14＝0；A16＝0。
coefficient of the 10 th plane:
K＝-7.8715412；A4＝0.012491331；A6＝-0.00099013962；A8＝3.85329e-005；A10＝-9.1141573e-008；A12＝-2.8086635e-008；A14＝0；A16＝0。
the embodiment of the utility model provides a camera lens has following optical technical index:
the total optical length TTL is less than or equal to 23.6 mm; focal length f' of the lens: 6 mm; angle of view of lens: 61.5 degrees; optical distortion of the lens: -7.8%; aperture FNO of lens system: f1.6; size of a lens image plane: 1/2.7' (≧ phi 6.6 mm).
The imaging system provided by the present embodiment is further described below by performing detailed performance analysis on the embodiment.
The optical transfer function is used for evaluating the imaging quality of the imaging system in a more accurate, visual and common mode, the higher and smoother curve of the optical transfer function shows that the imaging quality of the system is better, and various aberrations (such as spherical aberration, coma aberration, astigmatism, field curvature, axial chromatic aberration, vertical axis chromatic aberration and the like) are well corrected.
As shown in fig. 2, it is a graph of an optical transfer function (MTF) of the imaging system in a normal temperature state in the visible light band; as shown in fig. 3, is a graph of the optical transfer function (MTF) of the imaging system in the visible band-30 ℃; as shown in fig. 4, is a graph of the optical transfer function (MTF) of the imaging system in the visible band +70 ℃; as shown in fig. 5, it is a graph of the optical transfer function (MTF) of the imaging system in the infrared band at normal temperature. As can be seen from fig. 2 to 5, the optical transfer function (MTF) curve of the imaging system in the normal temperature state in the visible light portion is smooth and concentrated, and the average MTF value of the full field of view (half image height Y' is 3.3mm) reaches 0.45 or more; therefore, the imaging system provided by the embodiment can achieve high resolution, and meet the imaging requirement of a 1/2.7 inch 600 ten thousand pixel camera; meanwhile, at-30 ℃ and +70 ℃, the optical transfer function (MTF) curve graph of the lens provided by the proposal is smooth and concentrated, and the average value of the MTF of the full field of view (the half-image height Y' is 3.3mm) reaches more than 0.35, so that high imaging quality can be still maintained, and the lens is ensured to be suitable for complex environments. Meanwhile, when the infrared band is in a normal temperature state, an optical transfer function (MTF) curve graph of the lens provided by the proposal is smooth and concentrated, and the average value of the MTF of a full field of view (the half-image height Y' is 3.3mm) reaches above 0.4, so that high imaging quality can be still kept, and all-weather high-definition video monitoring is realized.
An embodiment of the present invention provides a lens assembly, which includes a first negative power lens, a second negative power lens, a first positive power lens, a second positive power lens, a third negative power lens, a third positive power lens and an image plane sequentially arranged from an object side to an image side; the lens satisfies the following conditions: f 2/f' is not less than-2.8 and not more than-2.0; f 4/f' is more than or equal to 0.8 and less than or equal to 1.4; f 5/f' is more than or equal to 1.0 and less than or equal to 1.6; wherein f2 is the focal length of the second negative power lens, f4 is the focal length of the second positive power lens, f5 is the focal length of the third negative power lens, and f' is the focal length of the lens. In the embodiment of the present invention, the lenses are arranged in the lens from the object side to the image side in a specific order, and the lenses in the lens satisfy the condition-2.8 ≦ f2/f ≦ -2.0; f 4/f' is more than or equal to 0.8 and less than or equal to 1.4; f 5/f' is more than or equal to 1.0 and less than or equal to 1.6, therefore the utility model provides a lens is big light ring heat dissipation difference ripples and plastics mixture tight shot.
While the preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the appended claims be interpreted as including the preferred embodiment and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (10)
1. The lens is characterized by comprising a first negative focal power lens, a second negative focal power lens, a first positive focal power lens, a second positive focal power lens, a third negative focal power lens, a third positive focal power lens and an imaging surface which are sequentially arranged from an object side to an image side;
the lens satisfies the following conditions:
-2.8≤f2/f’≤-2.0；
0.8≤f4/f’≤1.4；
1.0≤f5/f’≤1.6；
wherein f2 is the focal length of the second negative power lens, f4 is the focal length of the second positive power lens, f5 is the focal length of the third negative power lens, and f' is the focal length of the lens.
2. The lens barrel as claimed in claim 1, wherein the first negative power lens includes a meniscus lens whose surface facing the object side is convex.
3. The lens barrel as claimed in claim 1, wherein the second negative power lens includes a plastic aspherical lens having a concave surface facing the object side.
4. The lens barrel as claimed in claim 1, wherein the second positive power lens includes a plastic aspherical lens which is a biconvex lens.
5. The lens barrel as claimed in claim 1, wherein the third negative power lens includes a plastic aspherical lens having a concave surface facing the object side.
6. The lens barrel as claimed in claim 1, wherein the first positive power lens and the third positive power lens include a double convex lens.
7. The lens barrel as claimed in claim 1, wherein the refractive index of the second negative power lens is 1.55 or less; the refractive index of the third negative-power lens is 1.62 or more.
8. The lens barrel according to claim 1, wherein an abbe number of the second negative power lens is 55 or more; the abbe number of the first positive focal power lens is more than or equal to 65; the third negative-power lens has an abbe number of 25 or less.
9. The lens barrel as claimed in claim 1, wherein a diaphragm is disposed between the second negative power lens and the first positive power lens.
10. The lens barrel as claimed in claim 1, wherein a color filter is disposed between the third positive power lens and the imaging surface.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113325548A (en) * | 2021-05-17 | 2021-08-31 | 浙江大华技术股份有限公司 | Lens |
| CN113589479A (en) * | 2021-07-13 | 2021-11-02 | 浙江大华技术股份有限公司 | Imaging system |
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2019
- 2019-08-21 CN CN201921363677.6U patent/CN210626760U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113325548A (en) * | 2021-05-17 | 2021-08-31 | 浙江大华技术股份有限公司 | Lens |
| CN113325548B (en) * | 2021-05-17 | 2024-04-12 | 浙江大华技术股份有限公司 | Lens |
| CN113589479A (en) * | 2021-07-13 | 2021-11-02 | 浙江大华技术股份有限公司 | Imaging system |
| CN113589479B (en) * | 2021-07-13 | 2023-10-10 | 浙江大华技术股份有限公司 | Imaging system |
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