Six-piece 4k front-view narrow-angle camera and imaging method thereof

Abstract

The present application relates to a kind of six-piece 4K front view narrow-angle camera and its imaging method, the optical system of the camera has the lens with optical power, in turn, first lens, second lens, third lens, fourth lens, fifth lens and sixth lens along the light path incidence direction, diaphragm is arranged between first lens and second lens;First lens is meniscus negative lens, its object side is convex, and image side is concave;Second lens is double-concave negative lens;Third lens is double-convex positive lens;Fourth lens is double-convex positive lens;Fifth lens is meniscus negative lens, its object side is concave, and image side is convex;Sixth lens is double-concave negative lens;All lenses are made of glass material, wherein first, fourth lens is aspheric lens, and second lens and third lens are tightly connected to form cemented lens group.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lenses, in particular to a six-piece 4K forward-looking narrow-angle camera and an imaging method thereof. BACKGROUND

[0002] At present, vehicle-mounted cameras mounted on vehicles are mainly divided into five categories according to the installation position, namely, forward-looking cameras, surround-view cameras, rear-view cameras, side-view cameras and built-in cameras. The forward-looking camera is mainly installed on the front windshield and is used to realize the visual perception and recognition function of driving. According to the function, it can be divided into a forward-looking main camera, a forward-looking narrow-angle camera and a forward-looking wide-angle camera. The forward-looking narrow-angle camera is mainly used for target recognition such as traffic lights and pedestrians. Generally, a narrow-angle lens is selected, and a lens with an angle of about 30°~40° can be selected. On this basis, the market pursues higher pixel density and longer detection distance to improve the accuracy and application range of visual perception and recognition of driving. In order to improve the performance, the market mainly uses a structure of seven pieces or more, which is not conducive to cost reduction and promotion of the lens. SUMMARY

[0003] Therefore, the purpose of the present application is to provide a six-piece 4K forward-looking narrow-angle camera and an imaging method thereof, which realizes six-piece 4K clear imaging while having a small size.

[0004] The present application adopts the following scheme: a six-piece 4K forward-looking narrow-angle camera, the optical system of the camera has lenses with optical power along the light path in the incident direction in sequence: a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, and a diaphragm is arranged between the first lens and the second lens; the first lens is a meniscus negative lens, the object side surface of which is convex, and the image side surface is concave; the second lens is a double-concave negative lens; the third lens is a double-convex positive lens; the fourth lens is a double-convex positive lens; the fifth lens is a meniscus negative lens, the object side surface of which is concave, and the image side surface is convex; the sixth lens is a double-concave negative lens; all the lenses are made of glass material, wherein the first and fourth lenses are aspherical lenses, and the second and third lenses are in close contact to form a cemented lens group.

[0005] Further, the focal length of the optical system is f, and the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are f1, f2, f3, f4, f5 and f6 respectively, wherein f1, f2, f3, f4, f5 and f6 satisfy the following ratio: -8.0<f1 / f<-7.0, -1.0<f2 / f<0.0, 0.0<f3 / f<1.0, 0.0<f4 / f<1.0, -9.0<f5 / f<-8.0, -1.0<f6 / f<0.0.

[0006] Further, the first lens satisfies the relationship: 1.5≤N d ≤1.8, 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 ≤1.8, V d ≥50.0; the fourth lens satisfies the relationship: 1.0≤N d ≤1.5, V d ≥50.0; the fifth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; the sixth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; wherein N d is the refractive index, and V d is the Abbe number.

[0007] Further, the air gap between the first lens and the diaphragm is 1.0-1.5mm; the air gap between the diaphragm and the second lens is 0.5-1.0mm; the second lens and the third lens are a cemented lens group, and the air gap is 0mm; the air gap between the third lens and the fourth lens is 0.1-0.5mm; the air gap between the fourth lens and the fifth lens is 0.1-0.5mm; and the air gap between the fifth lens and the sixth lens is 1.0-1.5mm.

[0008] Further, the total optical length TTL of the optical system and the focal length f of the optical system satisfy: TTL / f≤2.0.

[0009] Further, the F number of the optical system is ≤1.6.

[0010] Further, the image height H of the optical system and the focal length f of the optical system satisfy: H / f≤1.0.

[0011] Further, the rear side of the sixth lens is provided with a filter.

[0012] Another technical solution of the present application is an imaging method of the six-piece 4K forward-looking narrow-angle camera as described above, and light rays are sequentially imaged after passing through the first lens, the diaphragm, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the filter.

[0013] Compared with the prior art, the present application has the following beneficial effects:

[0014] 1. The lens has an imaging angle of more than 30 degrees for an object, and has the advantages of 4K imaging definition, large light aperture, low tolerance sensitivity, good high and low temperature stability, etc., and can more comprehensively monitor the scene in front of the vehicle and at a distance;

[0015] 2. By reasonably matching each optical lens, the system structure is six pieces, while ensuring compactness and reasonableness, easy assembly, low tolerance sensitivity, and more suitable for large-scale high-yield production;

[0016] 3. The full glass structure has high stability, can compensate for the displacement of the focusing surface at high and low temperatures, and has complex environment adaptability;

[0017] 4. The axial color difference, vertical axial color difference and high-order color difference are corrected to ensure that the imaging system also has high imaging quality at a large angle.

[0018] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the following will further detail the present application through specific examples and related drawings. BRIEF DESCRIPTION OF DRAWINGS

[0019] Fig. 1 is a schematic diagram of the optical system structure of the camera of the present application;

[0020] Fig. 2 is the axial color difference graph of the full working waveband of the present application;

[0021] Fig. 3 is the vertical axial color difference graph of the full working waveband of the present application;

[0022] Fig. 4 is the field curvature distortion graph of the full working waveband of the present application;

[0023] In the figure: STO - diaphragm; L1 - first lens; L2 - second lens; L3 - third lens; L4 - fourth lens; L5 - fifth lens; L6 - sixth lens; L7 - seventh lens; L8 - equivalent glass flat plate; L9 - equivalent glass flat plate; IMA - imaging surface. DETAILED DESCRIPTION

[0024] It should be pointed out that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as generally understood by those skilled in the art to which the present application belongs.

[0025] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, devices, components and / or combinations thereof, but do not preclude the presence or addition of one or more other features, steps, operations, devices, components and / or combinations thereof.

[0026] As shown in Figs. 1-4 A six-piece 4K front-view narrow-angle camera, the optical system of the camera has lenses with optical power in the order of first lens, second lens, third lens, fourth lens, fifth lens and sixth lens along the light path incident direction, and a diaphragm is arranged between the first lens and the second lens; without considering the reverse bending caused by the aspherical coefficient, the first lens is a meniscus negative lens, the object side surface of which is convex, and the image side surface is concave; the second lens is a double-concave negative lens, the object side surface of which is concave, and the image side surface is concave; the third lens is a double-convex positive lens, the object side surface of which is convex, and the image side surface is convex; the fourth lens is a double-convex positive lens, the object side surface of which is convex, and the image side surface is convex; the fifth lens is a meniscus negative lens, the object side surface of which is concave, and the image side surface is convex; the sixth lens is a double-concave negative lens, the object side surface of which is concave, and the image side surface is concave; all the lenses are made of glass material, the second lens, the third lens, the fifth lens and the sixth lens are spherical lenses, and the first lens and the fourth lens are aspherical lenses, and the second lens and the third lens are in close contact to form a cemented lens group.

[0027] Among them, the first lens has a negative optical power lens, which adjusts the large angle of light at the same time, as an aspherical lens, it has the effect of reducing the distortion and other aberrations of the optical system. The second lens and the third lens form an achromatic double-cemented lens. Reasonable lens matching makes the optical system realize small volume, 4K, large aperture, day and night focus, low temperature drift design through six-piece structure, and the on-axis and off-axis aberrations are well corrected, and the imaging quality is good, as shown in Figs. 2-4 .

[0028] In the embodiment, the focal length of the optical system is f, and the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are f1, f2, f3, f4, f5 and f6 respectively, wherein f1, f2, f3, f4, f5 and f6 satisfy the following proportions: -8.0<f1 / f<-7.0, -1.0<f2 / f<0.0, 0.0<f3 / f<1.0, 0.0<f4 / f<1.0, -9.0<f5 / f<-8.0, -1.0<f6 / f<0.0.

[0029] In the embodiment, the first lens satisfies the relationship: 1.5≤N d ≤1.8, Vd ≤ 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 ≤ 1.8, V d ≥ 50.0; the fourth lens satisfies the relationship: 1.0 ≤ N d ≤ 1.5, V d ≥ 50.0; the fifth lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≤ 50.0; the sixth lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≤ 50.0; wherein N d is the refractive index, and V d is the Abbe number.

[0030] In this embodiment, the air gap between the first lens and the diaphragm is 1.0-1.5 mm; the air gap between the diaphragm and the second lens is 0.5-1.0 mm; the second lens and the third lens are a cemented lens group, and the air gap is 0 mm; the air gap between the third lens and the fourth lens is 0.1-0.5 mm; the air gap between the fourth lens and the fifth lens is 0.1-0.5 mm; and the air gap between the fifth lens and the sixth lens is 1.0-1.5 mm.

[0031] In this embodiment, the first and fourth lenses are both aspherical lenses. The aspherical curve equation expression is:

[0032]

[0033] wherein Z is the sagittal height of the aspherical surface at a position along the optical axis at a height of r from the vertex of the aspherical surface; c is the paraxial curvature of the aspherical surface; k is the conic constant; and A , , , , , , , are high-order term coefficients.

[0034] The aspherical surface coefficients of the aspherical lenses of the optical system of this embodiment are as follows:

[0035]

[0036] In this embodiment, the optical total length TTL of the optical system and the focal length f of the optical system satisfy: TTL / f ≤ 2.0.

[0037] In the embodiment, the F number of the optical system is ≤1.6.

[0038] In the embodiment, the image height H of the optical system and the focal length f of the optical system satisfy: H / f ≤1.0.

[0039] In the embodiment, the rear side of the sixth lens is provided with a filter.

[0040] The technical index realized by the optical system in the embodiment is as follows:

[0041] (1) focal length: 14.0 ≤ EFFL ≤ 15.0 mm;

[0042] (2) aperture F ≤ 1.6;

[0043] (3) field of view angle: 2w ≥ 30°;

[0044] (4) working waveband: visible light waveband.

[0045] To realize the design parameters, the specific design of the optical system in the embodiment is as shown in the following table:

[0046]

[0047] The optical system in the embodiment realizes the miniaturization of the lens group by reasonably allocating the optical power, surface shape, central thickness of each lens and the on-axis distance between each lens, etc., while meeting the 4K imaging performance requirements of the six-piece lens.

[0048] The mechanical structure part (i.e. the lens barrel structure) of the camera belongs to the conventional prior art, and will not be specifically described here.

[0049] An imaging method of the six-piece 4K forward-looking narrow-angle camera as described above, in which light rays are sequentially imaged after passing through the first lens, the diaphragm, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the filter.

[0050] Any technical solution disclosed in the present application, unless otherwise stated, if it discloses a numerical range, the disclosed numerical range is a preferred numerical range, any person skilled in the art should understand that the preferred numerical range is only one of the many implementable numerical values with more obvious technical effects or representative values. Because there are too many values, it is impossible to enumerate them all, so the present application only discloses some values to illustrate the technical solutions of the present application, and the above-mentioned values should not constitute a limitation on the protection scope of the present application.

[0051] If the present application discloses or involves mutually fixedly connected parts or structural members, unless otherwise stated, the fixed connection can be understood as: detachably fixedly connected (for example, connected using bolts or screws), and can also be understood as: non-detachable fixed connection (for example, riveting, welding), of course, the mutually fixed connection can also be replaced by an integral structure (for example, integrally formed by using a casting process) (obviously, an integral forming process cannot be used).

[0052] In addition, the terms used to represent the positional relationship or shape in any of the technical solutions disclosed in the present application include states or shapes similar, similar or close to them, unless otherwise stated.

[0053] Any component provided by the present application can be assembled from multiple individual components, or can be a single component manufactured by an integral forming process.

[0054] The above is only a preferred embodiment of the present application, and is not intended to limit the present application in other forms. Any person skilled in the art can modify or change the above disclosed technical content to equivalent embodiments. However, any simple modification, equivalent change and modification made to the above embodiments without departing from the technical solution of the present application, according to the technical essence of the present application, still belongs to the protection scope of the technical solution of the present application.

Claims

1. A six-piece 4K front-viewing narrow-angle camera, characterized by: The optical system of the camera has lenses with optical power in sequence along the light path in the incident direction as a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, a diaphragm is arranged between the first lens and the second lens, and the number of lenses with optical power in the camera is 6; the first lens is a meniscus negative lens, the object side surface of which is a convex surface and the image side surface of which is a concave surface; the second lens is a double-concave negative lens; the third lens is a double-convex positive lens; the fourth lens is a double-convex positive lens; the fifth lens is a meniscus negative lens, the object side surface of which is a concave surface and the image side surface of which is a convex surface; the sixth lens is a double-concave negative lens; all the lenses are made of glass material, wherein the first lens and the fourth lens are aspherical lenses, and the second lens and the third lens are in close contact to form a cemented lens group; the focal length of the optical system is f, and the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are f1, f2, f3, f4, f5 and f6 respectively, wherein f1, f2, f3, f4, f5 and f6 and f satisfy the following ratios: -8.0 < f1 / f < -7.0, -1.0 < f2 / f < 0.0, 0.0 < f3 / f < 1.0, 0.0 < f4 / f < 1.0, -9.0 < f5 / f < -8.0, and -1.0 < f6 / f < 0.0; the total optical length TTL of the optical system and the focal length f of the optical system satisfy: TTL / f ≤ 2.0; the image height H of the optical system and the focal length f of the optical system satisfy: H / f ≤ 1.

0.

2. The six-piece 4K front-view narrow-angle camera of claim 1, wherein: The first lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, 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 ≤ 1.8, V d ≥ 50.0; the fourth lens satisfies the relationship: 1.0 ≤ N d ≤ 1.5, V d ≥ 50.0; the fifth lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≤ 50.0; the sixth lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≤ 50.0; wherein N d is the refractive index, and V d is the Abbe number.

3. The six-piece 4K front-view narrow-angle camera of claim 1, wherein: The air gap between the first lens and the diaphragm is 1.0-1.5 mm; the air gap between the diaphragm and the second lens is 0.5-1.0 mm; the second lens and the third lens form a cemented lens group with an air gap of 0 mm; the air gap between the third lens and the fourth lens is 0.1-0.5 mm; the air gap between the fourth lens and the fifth lens is 0.1-0.5 mm; and the air gap between the fifth lens and the sixth lens is 1.0-1.5 mm.

4. The six-piece 4K front-view narrow-angle camera of claim 1, wherein: The F number of the optical system is ≤1.

6.

5. The six-piece 4K front-view narrow-angle camera of claim 1, wherein: The rear side of the sixth lens is provided with a filter.

6. The imaging method of the six-piece 4K front-view narrow-angle camera according to claim 5, characterized in that: Light rays are sequentially imaged through the first lens, the diaphragm, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the filter.

Images