A small monitoring lens

Abstract

The present application relates to a kind of small monitoring lens, the optical system of the lens includes first lens, second lens, third lens and fourth lens arranged in turn along the light path of incidence;First lens is meniscus negative lens, object side is convex, image side is concave;Second lens is double convex positive lens;Third lens is double convex positive lens;Fifth lens is meniscus negative lens, object side is concave, image side is convex;Wherein second lens is glass spherical lens, first, third and fourth lens are plastic aspherical lens.The small monitoring lens of the present application adopts four optical lenses, adopts 1G3P optical structure, the surface shape, thickness of each lens is reasonably set, so that the lens high-definition imaging is controlled within 21mm at the same time, the outer diameter is controlled within 10mm;Strong light ability, can better adapt to a variety of environmental brightness conditions;With simple structure, low tolerance sensitivity and low cost and the like advantages.

Description

Technical Field

[0001] This invention relates to the field of lens technology, and in particular to a small surveillance lens. Background Technology

[0002] In recent years, the development of computer technology, network technology, multimedia technology, image processing technology, transmission technology, and display technology has provided strong technical support for the implementation of intelligent video network surveillance in modern cities. Meanwhile, optical lenses, as the core component of security video surveillance cameras, play a crucial role in the imaging quality of these cameras. With the increasing variety of video surveillance applications, the requirements for image quality and size of optical lenses are also constantly increasing. However, currently used ultra-high-definition optical lenses for video surveillance cameras generally have the following drawbacks: while improving image quality, they struggle to meet the requirements of large aperture and small size. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a small surveillance lens that meets the requirements of high-definition imaging, good environmental stability, and large light-transmitting aperture, while the lens as a whole is more compact and has a smaller overall length and outer diameter.

[0004] The present invention is implemented using the following scheme: a small surveillance lens, the optical system of which includes a first lens, a second lens, a third lens and a fourth lens arranged sequentially along the incident light path; the first lens is a meniscus negative lens with a convex object side and a concave image side; the second lens is a biconvex positive lens; the third lens is a biconvex positive lens; the fifth lens is a meniscus negative lens with a concave object side and a convex image side; wherein the second lens is a glass spherical lens, and the first, third and fourth lenses are all plastic aspherical lenses.

[0005] Furthermore, the focal length ƒ of the optical system, and the focal lengths of the first lens, the second lens, the third lens, and the fourth lens are ƒ1, ƒ2, ƒ3, and ƒ4, respectively, wherein ƒ1, ƒ2, ƒ3, and ƒ4 satisfy the following ratios with ƒ: -2.0 < ƒ1 / ƒ < -0.5, 1.0 < ƒ2 / ƒ < 2.5, 0.5 < ƒ3 / ƒ < 2.0, 2.0 < |ƒ4 / ƒ| < 4.0.

[0006] Furthermore, the first lens satisfies the relationship: 1.5 ≤ N d ≤1.65, V d ≥50.0; The second lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; The third lens satisfies the relationship: 1.5≤N d ≤1.65, V d ≥50.0; The fourth lens satisfies the relationship: 1.6≤N d≤1.8, V d ≤50.0; where N d V is the refractive index. d Let be Abbe's constant.

[0007] Furthermore, the equations for the aspherical curves of the first lens, the third lens, and the fourth lens are as follows: , Where Z is the distance from the vertex of the aspherical surface to the optical axis at a height of h; c is the paraxial curvature of the aspherical surface; k is the conic constant; and α1, α2, α3, α4, α5, α6, α7, and α8 are all higher-order coefficients.

[0008] Furthermore, the total optical length TTL of the optical system and the focal length ƒ of the optical system satisfy the following condition: TTL / ƒ≤6.0.

[0009] Furthermore, the outer diameter Φ of the optical system and the focal length ƒ of the optical system satisfy the following condition: Φ / ƒ≤2.0.

[0010] Furthermore, the F-number of the optical system is ≤1.65.

[0011] Furthermore, the image height H of the optical system and the focal length ƒ of the optical system satisfy the following condition: H / ƒ≥1.5.

[0012] Compared with the prior art, the present invention has the following beneficial effects: (1) The small monitoring lens of the present invention uses four optical lenses and adopts a 1G3P optical structure. The surface shape and thickness of each lens are reasonably set so that the lens can achieve high-definition imaging while the total length is controlled within 21mm and the outer diameter is controlled within 10mm.

[0013] (2) The F number is ≤1.65, which has strong light transmission ability and can better adapt to various environmental brightness conditions.

[0014] (3) Reasonably set the material and focal length of each lens so that the lens can still form clear images at working temperatures from -40℃ to 85℃.

[0015] (4) The combination of one glass spherical lens and three plastic aspherical lenses has the advantages of simple structure, low tolerance sensitivity and low cost.

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below through specific embodiments and related drawings. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the optical system structure according to Embodiment 1 of the present invention; Figure 2 This is the axial chromatic aberration diagram of the entire working band of Embodiment 1 of the present invention; Figure 3 This is the transverse chromatic aberration diagram of the entire working band of Embodiment 1 of the present invention; Figure 4 This is a field curvature distortion diagram of the entire working band of Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of the optical system structure according to Embodiment 2 of the present invention; Figure 6 This is the axial chromatic aberration diagram of the entire working band of Embodiment 2 of the present invention; Figure 7 This is the transverse chromatic aberration diagram of the entire working band of Embodiment 2 of the present invention; Figure 8 This is the field curvature distortion diagram of the entire working band of Embodiment 2 of the present invention; In the diagram: L1 - first lens; STO - aperture stop; L2 - second lens; L3 - third lens; L4 - fourth lens; L5 - equivalent glass plate; IMA - imaging plane. Detailed Implementation

[0018] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0019] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. Example 1: As Figures 1-4 As shown, a small surveillance lens, the optical system of which includes a first lens, a second lens, a third lens, and a fourth lens arranged sequentially along the incident light path; without considering the curvature caused by the aspherical coefficient, the first lens is a meniscus negative lens with a convex object side and a concave image side; the second lens is a biconvex positive lens; the third lens is a biconvex positive lens; the fifth lens is a meniscus negative lens with a concave object side and a convex image side; the lenses are made of glass and plastic materials, wherein the second lens is a glass spherical lens, and the first, third, and fourth lenses are all plastic aspherical lenses.

[0020] By rationally allocating the optical power of each lens, various aberrations in the system are effectively optimized; imaging quality at high and low temperatures is effectively guaranteed; the incident angle of light from each lens is effectively controlled, reducing lens sensitivity and simplifying production and assembly. This also results in a smaller overall length and outer diameter of the optical system.

[0021] In this embodiment, the focal length ƒ of the optical system, and the focal lengths of the first lens, the second lens, the third lens, and the fourth lens are ƒ1, ƒ2, ƒ3, and ƒ4, respectively, wherein ƒ1, ƒ2, ƒ3, and ƒ4 satisfy the following ratios with ƒ: -2.0 < ƒ1 / ƒ < -0.5, 1.0 < ƒ2 / ƒ < 2.5, 0.5 < ƒ3 / ƒ < 2.0, and 2.0 < |ƒ4 / ƒ| < 4.0.

[0022] In this embodiment, the first lens satisfies the relationship: 1.5 ≤ N d ≤1.65, V d ≥50.0; The second lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; The third lens satisfies the relationship: 1.5≤N d ≤1.65, V d ≥50.0; The fourth lens satisfies the relationship: 1.6≤N d ≤1.8, V d ≤50.0; where N d V is the refractive index. d Let be Abbe's constant.

[0023] In this embodiment, the equations for the aspherical curves of the first lens, the third lens, and the fourth lens are as follows: , Where Z is the distance from the vertex of the aspherical surface to the optical axis at a height of h; c is the paraxial curvature of the aspherical surface; k is the conic constant; and α1, α2, α3, α4, α5, α6, α7, and α8 are all higher-order coefficients.

[0024] In this embodiment, the total optical length TTL of the optical system and the focal length ƒ of the optical system satisfy the following condition: TTL / ƒ≤6.0.

[0025] In this embodiment, the outer diameter Φ of the optical system and the focal length ƒ of the optical system satisfy the following condition: Φ / ƒ≤2.0.

[0026] In this embodiment, the F-number of the optical system is ≤1.65.

[0027] In this embodiment, the image height H of the optical system and the focal length ƒ of the optical system satisfy the following condition: H / ƒ≥1.5.

[0028] The technical specifications achieved by the optical system in this embodiment are as follows: (1) Focal length: 3.5≤EFFL≤4.5mm; (2) Aperture F≤1.65; (3) Field of view: 2w≥100°; (4) Working band: visible light band.

[0029] To achieve the above design parameters, the specific parameter design of the optical system in this embodiment is shown in the table below (where the radius of curvature corresponding to the aspherical lens is the central radius of curvature):

[0030] The aspherical coefficients of the aspherical lenses in the optical system of this embodiment are shown in the table below:

[0031] The optical system in this embodiment effectively corrects on-axis and off-axis aberrations, enabling high-definition imaging. It also achieves a small size and small outer diameter design. Example 2: Figures 5-8 As shown, a small surveillance lens, the optical system of which includes a first lens, a second lens, a third lens, and a fourth lens arranged sequentially along the incident light path; without considering the curvature caused by the aspherical coefficient, the first lens is a meniscus negative lens with a convex object side and a concave image side; the second lens is a biconvex positive lens; the third lens is a biconvex positive lens; the fifth lens is a meniscus negative lens with a concave object side and a convex image side; the lenses are made of glass and plastic materials, wherein the second lens is a glass spherical lens, and the first, third, and fourth lenses are all plastic aspherical lenses.

[0032] By rationally allocating the optical power of each lens, various aberrations in the system are effectively optimized; imaging quality at high and low temperatures is effectively guaranteed; the incident angle of light from each lens is effectively controlled, reducing lens sensitivity and simplifying production and assembly. Simultaneously, this results in a smaller overall length and outer diameter of the optical system.

[0033] In this embodiment, the focal length ƒ of the optical system, and the focal lengths of the first lens, the second lens, the third lens, and the fourth lens are ƒ1, ƒ2, ƒ3, and ƒ4, respectively, wherein ƒ1, ƒ2, ƒ3, and ƒ4 satisfy the following ratios with ƒ: -2.0 < ƒ1 / ƒ < -0.5, 1.0 < ƒ2 / ƒ < 2.5, 0.5 < ƒ3 / ƒ < 2.0, and 2.0 < |ƒ4 / ƒ| < 4.0.

[0034] In this embodiment, the first lens satisfies the relationship: 1.5 ≤ N d ≤1.65, V d ≥50.0; The second lens satisfies the relationship: 1.5≤Nd ≤1.8, V d ≥50.0; The third lens satisfies the relationship: 1.5≤N d ≤1.65, V d ≥50.0; The fourth lens satisfies the relationship: 1.6≤N d ≤1.8, V d ≤50.0; where N d V is the refractive index. d Let be Abbe's constant.

[0035] In this embodiment, the equations for the aspherical curves of the first lens, the third lens, and the fourth lens are as follows: , Where Z is the distance from the vertex of the aspherical surface to the optical axis at a height of h; c is the paraxial curvature of the aspherical surface; k is the conic constant; and α1, α2, α3, α4, α5, α6, α7, and α8 are all higher-order coefficients.

[0036] In this embodiment, the total optical length TTL of the optical system and the focal length ƒ of the optical system satisfy the following condition: TTL / ƒ≤6.0.

[0037] In this embodiment, the outer diameter Φ of the optical system and the focal length ƒ of the optical system satisfy the following condition: Φ / ƒ≤2.0.

[0038] In this embodiment, the F-number of the optical system is ≤1.65.

[0039] In this embodiment, the image height H of the optical system and the focal length ƒ of the optical system satisfy the following condition: H / ƒ≥1.5.

[0040] The technical specifications achieved by the optical system in this embodiment are as follows: (1) Focal length: 3.5≤EFFL≤4.5mm; (2) Aperture F≤1.65; (3) Field of view: 2w≥100°; (4) Working band: visible light band.

[0041] To achieve the above design parameters, the specific parameter design of the optical system in this embodiment is shown in the table below (where the radius of curvature corresponding to the aspherical lens is the central radius of curvature):

[0042] The aspherical coefficients of the aspherical lenses in the optical system of this embodiment are shown in the table below:

[0043] The optical system in this embodiment effectively corrects on-axis and off-axis aberrations, enabling high-definition imaging. It also achieves a small size and small outer diameter design. Unless otherwise stated, if any of the technical solutions disclosed in this invention specify a numerical range, then the disclosed numerical range is a preferred numerical range. Anyone skilled in the art should understand that the preferred numerical range is merely one among many feasible numerical values ​​that has a more obvious or representative technical effect. Because there are many numerical values, it is impossible to list them all. Therefore, this invention discloses only some numerical values ​​to illustrate the technical solutions of this invention. Furthermore, the numerical values ​​listed above should not constitute a limitation on the scope of protection of this invention.

[0044] If this invention discloses or relates to mutually fixedly connected components or structural parts, then, unless otherwise stated, a fixed connection can be understood as: a detachable fixed connection (e.g., using bolts or screws), or a non-detachable fixed connection (e.g., riveting, welding). Of course, mutually fixed connections can also be replaced by an integral structure (e.g., manufactured in one piece using a casting process) (except where it is obviously impossible to use an integral molding process).

[0045] In addition, unless otherwise stated, the terms used in any of the technical solutions disclosed in this invention to indicate positional relationships or shapes include states or shapes that are similar to, close to, or approximate with those states or shapes.

[0046] Any component provided by this invention can be assembled from multiple individual components or can be a single component manufactured by a one-piece molding process.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A small surveillance camera, characterized in that: The optical system of the lens includes a first lens, a second lens, a third lens, and a fourth lens arranged sequentially along the incident light path; the first lens is a meniscus negative lens with a convex object-side surface and a concave image-side surface; the second lens is a biconvex positive lens; the third lens is a biconvex positive lens; and the fifth lens is a meniscus negative lens with a concave object-side surface and a convex image-side surface; wherein the second lens is a glass spherical lens, and the first, third, and fourth lenses are all plastic aspherical lenses; the first lens has a front surface curvature radius of 6.531 mm, a rear surface curvature radius of 1.865 mm, a thickness of 0.897 mm, a refractive index of 1.535, and an Abbe number of 55.711; the second lens has a front surface curvature radius of 10.216 mm, a rear surface curvature radius of -10.216 mm, and a thickness of 2.439 mm. The first lens has a thickness of 2.346 mm, a refractive index of 1.639, and an Abbe number of 55.447; the second lens has a front surface radius of curvature of 4.598 mm, a rear surface radius of curvature of -3.287, a thickness of 2.346 mm, a refractive index of 1.535, and an Abbe number of 55.711; the third lens has a front surface radius of curvature of -2.253 mm, a rear surface radius of curvature of -5.894, a thickness of 0.870 mm, a refractive index of 1.661, and an Abbe number of 20.382; the fourth lens has a front surface radius of curvature of -2.253 mm, a rear surface radius of curvature of -5.894, a thickness of 0.870 mm, a refractive index of 1.639, and an Abbe number of 20.382; the fifth lens has a thickness of 0.870 mm, a refractive index of 1.639, and an Abbe number of 55.447; the sixth lens has a front surface radius of curvature of -2.253 mm, a rear surface radius of curvature of -5.894, a thickness of 0.870 mm, a refractive index of 1.661, and an Abbe number of 20.382; the seventh lens has a thickness of 0.870 mm, ... The air gap between the second lens and the third lens is 5.224 mm, the air gap between the second lens and the aperture stop is -0.246 mm, the air gap between the aperture stop and the third lens is 3.070 mm, and the air gap between the third lens and the fourth lens is 0.111 mm. The outer diameter Φ of the optical system and the focal length ƒ of the optical system satisfy the following condition: Φ / ƒ≤2.0; the F-number of the optical system is ≤1.65; the image height H of the optical system and the focal length ƒ of the optical system satisfy the following condition: H / ƒ≥1.

5.

2. The miniature surveillance lens according to claim 1, characterized in that: The equations for the aspherical curves of the first, third, and fourth lenses are as follows: ， Where Z is the distance from the vertex of the aspherical surface to the optical axis at a height of h; c is the paraxial curvature of the aspherical surface; k is the conic constant; and α1, α2, α3, α4, α5, α6, α7, and α8 are all higher-order coefficients.

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