A camera lens for day and night zoom and large aperture monitoring system

Abstract

The invention relates to a day-and-night zoom large-aperture monitoring system camera lens, comprising a front lens group G1, an aperture C, a rear lens group G2, and a filter D, which are arranged in sequence from an object plane to an image plane along an incident light path. The front lens group G1 is a negative power lens group as a whole, which is composed of three lenses, which are a meniscus glass lens A-1, a double concave aspheric plastic lens A-2, and an aspheric plastic lens A-3 in sequence along the light path; the rear lens group G2 is a positive power lens group as a whole, which is composed of seven lenses, which are: a positive power double-cemented lens group composed of a glass lens B-1 and a glass lens B-2, a meniscus plastic aspheric lens B-3, an aspheric plastic lens B-4, a positive power double-cemented lens group composed of a glass lens B-5 and a glass lens B-6, and a meniscus aspheric plastic lens B-7. The monitoring system camera lens has a simple structure and clear imaging, and can be used for day-and-night confocal monitoring.

Description

Technical Field

[0001] The invention relates to a camera lens for a day and night zoom large aperture monitoring system. Background Art

[0002] Most existing zoom surveillance lenses have an F number equal to 1.6. With the construction of smart cities, the image quality requirements for surveillance cameras in low-light environments at night are getting higher and higher. In order to meet the camera needs in low-light environments at night, a camera lens with a larger light flux, i.e. a large aperture, is required. The aperture coefficient, i.e. the F value, is a parameter used to characterize the size of the aperture. The formula F=f / D (f: lens focal length D: lens aperture). At the same focal length, the smaller the F number, the larger the aperture of the lens, and the greater the light flux.

[0003] With the increasing number of nighttime surveillance scenes, the surveillance lens also needs to ensure the clarity of the lens in low-light and dark environments at night, as well as the image quality in high and low temperature environments. Most of the existing zoom surveillance lenses have an F number of about 1.6 at the short focal end and an F number of about 2.8 at the long focal end; the image clarity will be reduced when imaging in low-light environments at night; when using light source fill light to increase the ambient illumination in some special shooting environments, overexposure will occur due to fill light reflection, and details such as faces or license plates will be unclear. Summary of the invention

[0004] In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a day and night zoom large aperture monitoring system camera lens with a zoom range of 3mm~10mm. It not only has a reasonable structure, but also has clear imaging without focus deviation, which can meet the needs of day and night confocal monitoring.

[0005] In order to solve the above technical problems, the technical solution of the present invention is: a day and night zoom large aperture monitoring system camera lens, comprising a front lens group G1, an aperture C, a rear lens group G2, and a filter D arranged in sequence along the incident light path from the object plane to the image plane, wherein the front lens group G1 is a negative focal lens group as a whole, and is composed of three lenses, which are a negative focal meniscus glass lens A-1, a negative focal biconcave aspheric plastic lens A-2, a positive focal aspheric The rear lens group G2 is a positive power lens group, which consists of seven lenses, which are: a positive power double-cemented lens group composed of glass lens B-1 and glass lens B-2, a positive power meniscus plastic aspherical lens B-3, a negative power aspherical plastic lens B-4, a positive power double-cemented lens group composed of glass lens B-5 and glass lens B-6, and a positive power meniscus aspherical plastic lens B-7.

[0006] Furthermore, the distance between the front lens group G1 and the aperture C is D1, and the distance between the rear lens group G2 and the aperture C is D2; the distance between D1 and D2 satisfies the following relationship: 1.5 <D1<12.5, 0.4<D2<7.5。

[0007] Furthermore, the above lenses satisfy the following relationship: 1.5≤n1≤1.8, 1.5≤n2≤1.7, 1.5≤n3≤1.7, 1.4≤n4≤1.75, 1.5≤n5≤1.8, 1.5≤n6≤1.7, 1.5≤n7≤1.7, 1.4≤n8≤1.8, 1.4≤n9≤1.8, 1.5≤n10≤1.7, wherein n1~n10 are the refractive indices of the meniscus glass lens A-1 to the meniscus aspherical plastic lens B-7 respectively.

[0008] Furthermore, the above lenses satisfy the following relationship: -15.2≤f1≤-5.3, -20.3≤f2≤-15, 15≤f3≤25.4, 15≤f4≤20.8, -600≤f5≤-300, 24.4≤f6≤30.3, -35.7≤f7≤-25.2, 15.2≤f8≤20.5, -60.3≤f9≤-30.3, 30.1≤f10≤60.3, wherein f1~f10 are respectively the lens focal lengths of the meniscus glass lens A-1 to the meniscus aspherical plastic lens B-7.

[0009] Furthermore, the R value corresponding to the object plane to the image plane of the above-mentioned lens satisfies the following relationship: 70≤R1≤100, 5≤R2≤10, -700≤R3≤-300, 5≤R4≤15, 10≤R5≤20, 150≤R6≤250, 5≤R8≤10, -20≤R9≤-10, R10 is a plane R value equal to infinity, 15≤R11≤25, -250≤R12≤-150, -300≤R13≤-200, 15≤R14≤30, 5≤R15≤20, -10≤R16≤-3, 25≤R17≤50, 5≤R18≤20, 5≤R19≤15.

[0010] Furthermore, by reasonably distributing the optical focal length between the two lens groups, the relative positions of the two lens groups are changed by moving the electric motor during zooming, thereby achieving an optical zoom process.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] 1. The second lens (A-2) and the third lens (A-3) of the front lens group are replaced with two plastic aspherical lenses, which greatly corrects the spherical aberration of the light focused by the first glass lens.

[0013] 2. In the rear lens group, the B-1 and B-2 glass lenses use different refractive indices and Abbe numbers to form a double-cemented lens group, which corrects the chromatic aberration of the system and achieves better image quality. The eighth and ninth lenses along the optical path of the system use a double-cemented lens group composed of different refractive indices and Abbe numbers again to further correct some of the remaining chromatic aberration of the system.

[0014] 3. The use of two double-cemented glass lens groups and the complementary optical power between the plastic aspherical lenses ensure that the focus is the same as at room temperature in high and low temperature environments, and there is no focus shift, ensuring the clarity of the picture. The full-field MTF value is 160 lp / mm>0.3 in the short-focus state, and the full-field MTF value is 180 lp / mm>0.4 in the long-focus state.

[0015] The last lens along the optical path uses a plastic aspherical lens to correct the system aberrations and ensure that the main ray angle at the edge of the system field is <11°, thus ensuring the uniformity of the relative illumination of the imaging picture.

[0016] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the structure of an embodiment of the present invention.

[0018] In the figure: G1-front lens group G1, C-aperture C, G2-rear lens group G2, D-filter D, A-1-meniscus glass lens A-1, A-2-biconcave aspherical plastic lens A-2, A-3-aspherical plastic lens A-3, B-1-glass lens B-1, B-2-glass lens B-2, B-3-aspherical lens B-3, B-4-aspherical plastic lens B-4, B-5-glass lens B-5, B-6-glass lens B-6, B-7-aspherical plastic lens B-7. DETAILED DESCRIPTION

[0019] In order to make the above features and advantages of the present invention more clearly understood, embodiments are given below with reference to the accompanying drawings for detailed description.

[0020] like Figure 1As shown, a day and night zoom large aperture monitoring system camera lens comprises a front lens group G1, an aperture C, a rear lens group G2, and a filter D which are arranged in sequence from the object plane to the image plane along the incident light path. The front lens group G1 is a negative power lens group as a whole, and is composed of three lenses, which are a negative power meniscus glass lens A-1, a negative power biconcave aspheric plastic lens A-2, and a positive power aspheric plastic lens A-3 along the light path; the rear lens group G2 is a positive power lens group as a whole, and is composed of seven lenses, which are: a positive power double-cemented lens group composed of a glass lens B-1 and a glass lens B-2, a positive power meniscus plastic aspheric lens B-3, a negative power aspheric plastic lens B-4, a positive power double-cemented lens group composed of a glass lens B-5 and a glass lens B-6, and a positive power meniscus aspheric plastic lens B-7 along the light path.

[0021] In the embodiment of the present invention, the distance between the front lens group G1 and the aperture C is D1, and the distance between the rear lens group G2 and the aperture C is D2; the distance between D1 and D2 satisfies the following relationship: 1.5 <D1<12.5, 0.4<D2<7.5。

[0022] In the embodiment of the present invention, the above-mentioned lenses satisfy the following relationship: 1.5≤n1≤1.8, 1.5≤n2≤1.7, 1.5≤n3≤1.7, 1.4≤n4≤1.75, 1.5≤n5≤1.8, 1.5≤n6≤1.7, 1.5≤n7≤1.7, 1.4≤n8≤1.8, 1.4≤n9≤1.8, 1.5≤n10≤1.7, wherein n1~n10 are the refractive indices of the meniscus glass lens A-1 to the meniscus aspherical plastic lens B-7 respectively.

[0023] In the embodiment of the present invention, the above-mentioned lenses satisfy the following relationship: -15.2≤f1≤-5.3, -20.3≤f2≤-15, 15≤f3≤25.4, 15≤f4≤20.8, -600≤f5≤-300, 24.4≤f6≤30.3, -35.7≤f7≤-25.2, 15.2≤f8≤20.5, -60.3≤f9≤-30.3, 30.1≤f10≤60.3, wherein f1~f10 are respectively the lens focal lengths of the meniscus glass lens A-1 to the meniscus aspherical plastic lens B-7.

[0024] In the embodiment of the present invention, the R value corresponding to the object plane to the image plane of the above-mentioned lens satisfies the following relationship: 70≤R1≤100, 5≤R2≤10, -700≤R3≤-300, 5≤R4≤15, 10≤R5≤20, 150≤R6≤250, 5≤R8≤10, -20≤R9≤-10, R10 is a plane R value equal to infinity, 15≤R11≤25, -250≤R12≤-150, -300≤R13≤-200, 15≤R14≤30, 5≤R15≤20, -10≤R16≤-3, 25≤R17≤50, 5≤R18≤20, 5≤R19≤15.

[0025] In the embodiment of the present invention, the optical focal length between the two lens groups is reasonably distributed, and the relative positions of the two lens groups are changed by the movement of the electric motor during zooming, thereby achieving an optical zoom process.

[0026] In the embodiment of the present invention, a zoom range of 3mm~10mm can be achieved, and the monitoring range of the short focal end can achieve a field of view monitoring of 140° to 40° at the long focal end. The use of glass and plastic aspherical lens design allows the system to achieve an F number of 1.3 at the short focal end and an F number of 2.2 at the long focal end, which greatly increases the light throughput of the system, allowing the lens to clearly image without fill light in low-light environments at night, ensuring the brightness of the image; the use of a combination of glass lenses and plastic aspherical lenses improves the imaging quality while reducing the overall length of the system (the total length of the optical system is <50mm), which is suitable for the length requirements of the lens of the current mainstream imaging system.

[0027] In the embodiment of the present invention, the specific parameters of each lens are as follows:

[0028]

[0029] The aspheric coefficients of plastic lenses are as follows:

[0030]

[0031] The surface equation of the aspheric lens is as follows:

[0032]

[0033] Wherein, parameter c is the curvature corresponding to the radius, r is the radial coordinate, and its unit is the same as the lens length unit. k is the coefficient of the conic quadratic curve. When the k coefficient is less than -1, the surface curve is a hyperbola. When the k coefficient is equal to -1, it is a parabola. When the k coefficient is between -1 and 0, it is an ellipse. When the k coefficient is equal to 0, it is a circle. When the k coefficient is greater than 0, it is an oblate circle. α1 to α8 represent the coefficients corresponding to each radial coordinate respectively. The above parameters can be used to accurately set the shape and size of the aspheric lens.

[0034] The zoom focal length range of the present invention is 3mm~10mm, the aperture F number range is: 1.3~2.2, the field of view range is 138°~40°, and the total optical length is less than 50mm. It can be used in high and low temperature environments (-30°C~80°C).

[0035] Applicable to mainstream 1 / 2.7' chips, imaging target surface>=6.6mm, resolution>=4MP (4 million pixels), supporting wavelength range of 430nm~850nm, meeting the requirements of day and night confocal monitoring.

[0036] The present invention is not limited to the above-mentioned best implementation mode. Anyone can derive other various forms of day and night zoom large aperture monitoring system camera lenses under the enlightenment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims

1. A day and night zoom large aperture surveillance system camera lens, characterized by: The front lens group G1, the aperture C, the rear lens group G2, and the filter D are arranged in sequence along the incident light path from the object plane to the image plane. The front lens group G1 is a negative power lens group as a whole, which is composed of three lenses, which are meniscus glass lens A-1, double concave aspheric plastic lens A-2, and aspheric plastic lens A-3 in sequence along the light path; the rear lens group G2 is a positive power lens group as a whole, which is composed of seven lenses, which are in sequence along the light path: a positive power double-cemented lens group composed of glass lens B-1 and glass lens B-2, a meniscus plastic aspheric lens B-3, an aspheric plastic lens B-4, a positive power double-cemented lens group composed of glass lens B-5 and glass lens B-6, and a meniscus aspheric plastic lens B-7; The distance between the front lens group G1 and the aperture C is D1, and the distance between the rear lens group G2 and the aperture C is D2; the distance between D1 and D2 satisfies the following relationship: 1.5 <D1<12.5, 0.4<D2<7.5; The above lenses satisfy the following relationship: -15.2≤f1≤-5.3, -20.3≤f2≤-15, 15≤f3≤25.4, 15≤f4≤20.8, -600≤f5≤-300, 24.4≤f6≤30.3, -35.7≤f7≤-25.2, 15.2≤f8≤20.5, -60.3≤f9≤-30.3, 30.1≤f10≤60.3, wherein f1~f10 are respectively the lens focal lengths of the meniscus glass lens A-1 to the meniscus aspherical plastic lens B-7.

2. The day and night zoom large aperture surveillance system camera lens according to claim 1, characterized in that: The above lenses satisfy the following relationship: 1.5≤n1≤1.8, 1.5≤n2≤1.7, 1.5≤n3≤1.7, 1.4≤n4≤1.75, 1.5≤n5≤1.8, 1.5≤n6≤1.7, 1.5≤n7≤1.7, 1.4≤n8≤1.8, 1.4≤n9≤1.8, 1.5≤n10≤1.7, wherein n1~n10 are the refractive indices of the meniscus glass lens A-1 to the meniscus aspherical plastic lens B-7 respectively.

3. The day and night zoom large aperture surveillance system camera lens according to claim 1, characterized in that: The R value corresponding to the object plane to the image plane of the above lens satisfies the following relationship: 70≤R1≤100, 5≤R2≤10, -700≤R3≤-300, 5≤R4≤15, 10≤R5≤20, 150≤R6≤250, 5≤R8≤10, -20≤R9≤-10, R10 is a plane R value equal to infinity, 15≤R11≤25, -250≤R12≤-150, -300≤R13≤-200, 15≤R14≤30, 5≤R15≤20, -10≤R16≤-3, 25≤R17≤50, 5≤R18≤20, 5≤R19≤15.

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