Small imaging system and imaging method thereof

Abstract

The invention relates to a small imaging system and an imaging method thereof.The small imaging system comprises an optical system, the optical system is composed of a first lens, a second lens, a third lens, a fourth lens, a bonding lens set and a seventh lens which are sequentially arranged from left to right along a light incident light path, and the bonding lens set is composed of a fifth lens and a sixth lens; the first lens is a negative meniscus lens, the second lens is a positive meniscus lens, the third lens is a negative meniscus lens, the fourth lens is a biconvex positive lens, the fifth lens is a negative meniscus lens, the sixth lens is a biconvex positive lens, and the seventh lens is a negative meniscus lens. By reasonably distributing the focal power and the surface type of each lens, the central thickness of each lens, the axial distance between the lenses and the like, the imaging performance requirement of the lens is met, the total length of the lens and the radial size of each lens are reduced, and the miniaturization of the lens group is realized.

Description

Technical Field

[0001] This invention relates to a small imaging system and its imaging method. Background Technology

[0002] With the rapid development of intelligent driving and Advanced Driver Assistance Systems (ADAS), forward-facing automotive lenses, as core components of autonomous driving and safety assistance systems, are widely used in functions such as Lane Departure Warning (LDW), Automatic Emergency Braking (AEB), and Traffic Sign Recognition (TSR). Forward-facing lenses need to possess high resolution, wide field of view, strong light suppression capabilities, and low-light imaging performance to support target detection and image processing in complex scenarios, while meeting automotive-grade reliability requirements. Furthermore, with the increasing demand for optimized computing resources and power consumption in intelligent vehicles, lens design needs to achieve miniaturization and lightweighting while maintaining high optical performance to adapt to compact vehicle structures and limited installation space. Existing forward-facing lenses mostly employ all-glass lenses or high-element hybrid structures. While these offer good optical performance, they have significant drawbacks, such as high manufacturing costs, complex processing, and significant weight, which hinders lightweight vehicle design. These shortcomings limit the application of forward-facing lenses in high-performance ADAS systems, necessitating a new optical structure that balances cost, performance, and reliability. Summary of the Invention

[0003] The present invention improves upon the above-mentioned problems. Specifically, the technical problem to be solved by the present invention is to provide a small imaging system and imaging method that achieves clear imaging while having a small size and low manufacturing cost.

[0004] The present invention is configured as follows: it includes an optical system consisting of a first lens, a second lens, a third lens, a fourth lens, a cemented lens group, and a seventh lens arranged sequentially from left to right along the incident light path; the cemented lens group consists of a fifth lens and a sixth lens; the first lens is a meniscus negative lens, the second lens is a meniscus positive lens, the third lens is a meniscus negative lens, the fourth lens is a biconvex positive lens, the fifth lens is a meniscus negative lens, the sixth lens is a biconvex positive lens, and the seventh lens is a meniscus negative lens.

[0005] Furthermore, the object-side surface of the first lens is convex, and the image-side surface is concave; the object-side surface of the second lens is concave, and the image-side surface is convex; the object-side surface of the third lens is convex, and the image-side surface is concave; the object-side surface of the fourth lens is convex, and the image-side surface is convex; the object-side surface of the fifth lens is convex, and the image-side surface is concave; the object-side surface of the sixth lens is convex, and the image-side surface is convex; and the object-side surface of the seventh lens is convex, and the image-side surface is concave.

[0006] Furthermore, the focal length of the optical system is set as f, and the focal lengths of the first, second, third, fourth, fifth, sixth, and seventh lenses are f1, f2, f3, f4, f5, f6, and f7, respectively. The ratios of f1, f2, f3, f4, f5, f6, and f7 to f satisfy the following ratio: -2.0 <f1 / f<-1.0,4.0<f2 / f<5.0,-5.0<f3 / f<-4.0,1.0<f4 / f<2.0,-2.0<f5 / f<-1.0,1.0<f6 / f<2.0,-19.0<f7 / f<-18.0。

[0007] Furthermore, the first lens satisfies the relationship: 1.7 ≤ N d ≤2.0, V d ≥50; The second lens satisfies the relationship: 1.3≤N d ≤1.6, V d ≥50; The third lens satisfies the relationship: 1.7≤N d ≤2.0, V d ≤50; the fourth lens satisfies the relationship: 2.0≤N d ≤2.3, V d ≤50; the fifth lens satisfies the relationship: 2.0≤N d ≤2.3, V d ≤50; The sixth lens satisfies the relationship: 1.3≤N d ≤1.6, V d ≥50; The seventh lens satisfies the relationship: 1.3≤N d ≤1.6, V d ≥50; where N d V is the refractive index. d Let be Abbe's constant.

[0008] Furthermore, the air gap between the first lens and the second lens is 2.5~3.0mm; the air gap between the second lens and the third lens is 0.1~0.5mm; an aperture stop is provided between the third lens and the fourth lens, and the air gap between the third lens and the aperture stop is 0.5~1.0mm; the air gap between the aperture stop and the fourth lens is 0.0~0.5mm; the air gap between the fourth lens and the fifth lens is 0.5~1.0mm; the fifth lens and the sixth lens are a cemented lens group with an air gap of 0; and the air gap between the sixth lens and the seventh lens is 0.5~1.0mm.

[0009] Furthermore, the second, third, and seventh lenses are aspherical lenses, and the equation for the aspherical curve is expressed 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; α1, α2, α3, α4, α5, α6, α7, and α8 are all higher-order coefficients.

[0010] Furthermore, the total optical length (TTL) of the optical system and the focal length (f) of the optical system satisfy the following condition: TTL / f ≤ 4.8.

[0011] Furthermore, the F-number of the optical system is ≤1.8.

[0012] Furthermore, the image height H of the optical system and the focal length f of the optical system satisfy the following condition: H / f ≥ 1.0.

[0013] Furthermore, a filter, a sensor protective glass, and an imaging surface are sequentially arranged behind the seventh lens. Furthermore, in the imaging method of a small imaging system, when light is incident, the light path passes through the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens in sequence to form an image. Compared with the prior art, the present invention has the following beneficial effects: (1) The lens uses seven optical lenses, consisting of four glass spherical lenses and three plastic aspherical lenses to form the imaging system. The use of plastic aspherical lenses, which are much cheaper than glass lenses, reduces production costs while ensuring image quality; the total length of the lens is less than 20 mm and the outer diameter is less than 10 mm, which ensures the optical performance of the camera group while reducing the overall size of the lens and improving aesthetics; the second, third and seventh lenses of the lens are plastic aspherical lenses, which can balance the aberrations of each field of view and further improve the overall image quality of the lens; (2) the imaging angle of the lens is greater than 135 degrees, and it has the advantages of high imaging clarity, large light aperture and low tolerance sensitivity, which can monitor the scene outside the vehicle more comprehensively; (3) by reasonably matching the optical lenses, the system structure is compact and reasonable, easy to assemble, and has low tolerance sensitivity, making it more suitable for large-scale high-yield production; (4) the use of four glass lenses and three plastic lenses reduces costs while adapting to the environment; (5) the chromatic aberration, transverse chromatic aberration and higher-order chromatic aberration of each axis are corrected to ensure that the imaging system can have high imaging quality at large angles. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the optical structure of an embodiment of the present invention; Figure 2 This is an axial chromatic aberration diagram of the entire working band of this invention. Figure 3 This is a transverse chromatic aberration diagram of the entire working band of this invention; Figure 4 This is a field curvature distortion diagram of the entire working band of this invention embodiment; In the diagram: STO - aperture stop; L1 - first lens; L2 - second lens; L3 - third lens; L4 - fourth lens; L5 - fifth lens; L6 - sixth lens; L7 - seventh lens; IR - filter; CG - sensor protective glass; IMA - imaging plane. Detailed Implementation

[0015] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0016] Example: Figures 1-4 As shown, this embodiment of the invention provides a small imaging system, including an optical system. The optical system consists of a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a cemented lens group, and a seventh lens L7 arranged sequentially from left to right along the incident light path. The cemented lens group consists of a fifth lens L5 and a sixth lens L6. When light is incident, the light path passes through the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, and seventh lens in sequence to form an image.

[0017] Without considering the curvature caused by the aspherical coefficient, the first lens is a negative meniscus lens, the second lens is a positive meniscus lens, the third lens is a negative meniscus lens, the fourth lens is a biconvex positive lens, the fifth lens is a negative meniscus lens, the sixth lens is a biconvex positive lens, and the seventh lens is a negative meniscus lens.

[0018] The object-side surface of the first lens is convex, and the image-side surface is concave; the object-side surface of the second lens is concave, and the image-side surface is convex; the object-side surface of the third lens is convex, and the image-side surface is concave; the object-side surface of the fourth lens is convex, and the image-side surface is convex; the object-side surface of the fifth lens is convex, and the image-side surface is concave; the object-side surface of the sixth lens is convex, and the image-side surface is convex; and the object-side surface of the seventh lens is convex, and the image-side surface is concave.

[0019] The second and third lenses are plastic aspherical lenses, which, while adjusting for large-angle light, also reduce optical system distortion. The fifth and sixth lenses form an achromatic cemented doublet, controlling chromatic aberration within a reasonable range in the visible light spectrum. Figures 2 to 4 As shown, the reasonable lens combination enables the optical system to achieve a small size, a large field of view, and a large aperture, while also providing good correction for on-axis and off-axis aberrations, resulting in good image quality.

[0020] In this embodiment of the invention, the first lens, the fourth lens, the fifth lens, and the sixth lens are glass spherical lenses, the second lens, the third lens, and the seventh lens are plastic aspherical lenses, and the fifth lens and the sixth lens are a cemented lens group.

[0021] In this embodiment of the invention, the focal length of the optical system is set as f, and the focal lengths of the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, and seventh lens are f1, f2, f3, f4, f5, f6, and f7, respectively, wherein f1, f2, f3, f4, f5, f6, and f7 satisfy the following ratio with f: -2.0 <f1 / f<-1.0,4.0<f2 / f<5.0,-5.0<f3 / f<-4.0,1.0<f4 / f<2.0,-2.0<f5 / f<-1.0,1.0<f6 / f<2.0,-19.0<f7 / f<-18.0。

[0022] In this embodiment of the invention, the first lens satisfies the relationship: 1.7 ≤ N d ≤2.0, V d ≥50; The second lens satisfies the relationship: 1.3≤N d ≤1.6, V d ≥50; The third lens satisfies the relationship: 1.7≤N d ≤2.0, V d ≤50; the fourth lens satisfies the relationship: 2.0≤N d ≤2.3, V d ≤50; the fifth lens satisfies the relationship: 2.0≤N d ≤2.3, V d ≤50; The sixth lens satisfies the relationship: 1.3≤N d ≤1.6, V d ≥50; The seventh lens satisfies the relationship: 1.3≤N d ≤1.6, V d ≥50; where N d V is the refractive index. d Let be Abbe's constant.

[0023] In this embodiment of the invention, the on-axis distances between the lenses satisfy the following relationships: the air gap between the first lens and the second lens is 2.5~3.0mm; the air gap between the second lens and the third lens is 0.1~0.5mm; an aperture stop is provided between the third lens and the fourth lens, and the air gap between the third lens and the aperture stop is 0.5~1.0mm; the air gap between the aperture stop and the fourth lens is 0.0~0.5mm; the air gap between the fourth lens and the fifth lens is 0.5~1.0mm; the fifth lens and the sixth lens are a cemented lens group with an air gap of 0; and the air gap between the sixth lens and the seventh lens is 0.5~1.0mm.

[0024] In this embodiment of the invention, the second, third, and seventh lenses are aspherical lenses, and the equation of the aspherical curve is expressed 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.

[0025] In this embodiment of the invention, the total optical length (TTL) of the optical system and the focal length (f) of the optical system satisfy the following condition: TTL / f ≤ 4.8.

[0026] In this embodiment of the invention, the F-number of the optical system is ≤1.8.

[0027] In this embodiment of the invention, the image height H of the optical system and the focal length f of the optical system satisfy the following condition: H / f≥1.0.

[0028] In this embodiment of the invention, a filter IR, a sensor protective glass CG, and an imaging surface IMA are sequentially arranged behind the seventh lens.

[0029] In this embodiment of the invention, the optical system achieves the following technical specifications: (1) Focal length: 4.0≤EFFL≤4.5mm; (2) Aperture F≤1.8; (3) Field of view: 2w ≥ 135°; (4) Operating band: Visible light band.

[0030] To achieve the above design parameters, the specific design parameters of the optical system in this embodiment of the invention are shown in Table 1 below: Table 1 The aspherical coefficients of each aspherical lens in the optical system of this embodiment are shown in Table 2 below: Table 2 The optical system in this embodiment achieves miniaturization of the lens assembly and reduces costs by rationally allocating the optical power, surface shape, center thickness of each lens, and on-axis distance between each lens, while meeting the lens imaging performance requirements.

[0031] 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.

[0032] Furthermore, if the present 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 using a casting process) (except where it is obviously impossible to use an integral molding process).

[0033] If the terms "first" or "second" are used in this document to specify components, those skilled in the art should know that the use of "first" or "second" is merely for the purpose of distinguishing components in description, and unless otherwise stated, the above terms have no special meaning.

[0034] 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.

[0035] 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.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A small imaging system, characterized in that, The system includes an optical system comprising a first lens, a second lens, a third lens, a fourth lens, a cemented lens group, and a seventh lens arranged sequentially from left to right along the incident light path. The cemented lens group consists of a fifth lens and a sixth lens. The first lens is a meniscus negative lens, the second lens is a meniscus positive lens, the third lens is a meniscus negative lens, the fourth lens is a biconvex positive lens, the fifth lens is a meniscus negative lens, the sixth lens is a biconvex positive lens, and the seventh lens is a meniscus negative lens.

2. The miniature imaging system according to claim 1, characterized in that, The first lens has a convex object-side surface and a concave image-side surface; the second lens has a concave object-side surface and a convex image-side surface; the third lens has a convex object-side surface and a concave image-side surface; the fourth lens has a convex object-side surface and a convex image-side surface; the fifth lens has a convex object-side surface and a concave image-side surface; the sixth lens has a convex object-side surface and a convex image-side surface; and the seventh lens has a convex object-side surface and a concave image-side surface.

3. A miniature imaging system according to claim 1, characterized in that, The focal length of the optical system is set to f. The focal lengths of the first, second, third, fourth, fifth, sixth, and seventh lenses are f1, f2, f3, f4, f5, f6, and f7, respectively. The ratios of f1, f2, f3, f4, f5, f6, and f7 to f satisfy the following condition: -2.0 <f1 / f<-1.0,4.0<f2 / f<5.0,-5.0<f3 / f<-4.0,1.0<f4 / f<2.0,-2.0<f5 / f<-1.0,1.0<f6 / f<2.0,-19.0<f7 / f<-18.0。 4. A miniature imaging system according to claim 1, characterized in that, The first lens satisfies the relationship: 1.7 ≤ N d ≤2.0, V d ≥50; The second lens satisfies the relationship: 1.3≤N d ≤1.6, V d ≥50; The third lens satisfies the relationship: 1.7≤N d ≤2.0, V d ≤50; the fourth lens satisfies the relationship: 2.0≤N d ≤2.3, V d ≤50; the fifth lens satisfies the relationship: 2.0≤N d ≤2.3, V d ≤50; The sixth lens satisfies the relationship: 1.3≤N d ≤1.6, V d ≥50; The seventh lens satisfies the relationship: 1.3≤N d ≤1.6, V d ≥50; where N d V is the refractive index. d Let be Abbe's constant.

5. A miniature imaging system according to claim 1, characterized in that, The air gap between the first lens and the second lens is 2.5~3.0mm; the air gap between the second lens and the third lens is 0.1~0.5mm; an aperture stop is provided between the third lens and the fourth lens, and the air gap between the third lens and the aperture stop is 0.5~1.0mm; the air gap between the aperture stop and the fourth lens is 0.0~0.5mm; the air gap between the fourth lens and the fifth lens is 0.5~1.0mm; the fifth lens and the sixth lens are a cemented lens group with no air gap; the air gap between the sixth lens and the seventh lens is 0.5~1.0mm.

6. A miniature imaging system according to claim 1, characterized in that, The second, third, and seventh lenses are aspherical lenses, and the equation for the aspherical curve is 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; α1, α2, α3, α4, α5, α6, α7, and α8 are all higher-order coefficients.

7. A miniature imaging system according to claim 1, characterized in that, The total optical length (TTL) of an optical system and the focal length (f) of the optical system satisfy the following condition: TTL / f ≤ 4.

8.

8. A miniature imaging system according to claim 1, characterized in that, The F-number of the optical system is ≤1.

8.

9. A miniature imaging system according to claim 1, characterized in that, The image height H of the optical system and the focal length f of the optical system satisfy the following condition: H / f≥1.

0.

10. An imaging method using a small imaging system as described in any one of claims 1-9, characterized in that, When light is incident, the light path passes through the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, and seventh lens in sequence to form an image.

Images