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

Abstract

The application relates to a seven-piece 4K front-view narrow-angle camera and an imaging method thereof. The optical system of the camera has lenses with optical powers arranged 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, a sixth lens and a seventh lens. A diaphragm is arranged between the third lens and the fourth lens. The first lens is a double-concave negative lens. The second lens is a double-convex positive lens. The third lens is a double-convex positive lens. The fourth lens is a double-convex positive lens. The fifth lens is a double-concave negative lens. The sixth lens is a meniscus positive lens, the object side surface of which is a convex surface, and the image side surface of which is a concave surface. The seventh 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. All the lenses are made of glass material, wherein the sixth lens and the seventh lens are aspherical lenses, and the fourth lens and the fifth lens are tightly arranged to form a cemented lens group.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lenses, in particular to a seven-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 the recognition of targets 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. SUMMARY

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

[0004] The present application adopts the following scheme: a seven-piece 4K forward-looking narrow-angle camera, the optical system of the camera has lenses with optical power along the light path in the order of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens, and a diaphragm is arranged between the third lens and the fourth lens; the first lens is a double-concave negative lens; the second lens is a double-convex positive lens; the third lens is a double-convex positive lens; the fourth lens is a double-convex positive lens; the fifth lens is a double-concave negative lens; the sixth lens is a meniscus positive lens, the object side is convex, and the image side is concave; the seventh lens is a meniscus negative lens, the object side is concave, and the image side is convex; all the lenses are made of glass material, wherein the sixth and seventh lenses are aspherical lenses, and the fourth and fifth lenses are tightly connected 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, the sixth lens and the seventh lens are f1, f2, f3, f4, f5, f6 and f7 respectively, wherein f1, f2, f3, f4, f5, f6 and f7 satisfy the following proportions: -1.0 < f1 / f < 0.0, 1.0 < f2 / f < 2.0, 1.0 < f3 / f < 2.0, 0.0 < f4 / f < 1.0, -1.0 < f5 / f < 0.0, 1.0 < f6 / f < 2.0, and -2.0 < f7 / f < -1.0.

[0006] Further, the first lens satisfies the relationship: 1.7≤N d ≤2.0, V d ≤50.0; the second lens satisfies the relationship: 1.7≤N d ≤2.0, 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: 1.5≤N d ≤1.8, V d ≥50.0; the fifth lens satisfies the relationship: 1.7≤N d ≤2.0, V d ≤50.0; the sixth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; the seventh 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 second lens is 1.5-2.0 mm; the air gap between the second lens and the third lens is 0.1-0.5 mm; the air gap between the third lens and the diaphragm is 0.1-0.5 mm; the air gap between the diaphragm and the fourth lens is 0.1-0.5 mm; the fourth lens and the fifth lens are a cemented lens group, and the air gap is 0 mm; the air gap between the fifth lens and the sixth lens is 3.5-4.0 mm; and the air gap between the sixth lens and the seventh lens is 2.5-3.0 mm.

[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 ≤1.5.

[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 seventh lens is provided with a filter.

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

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

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

[0015] 2、By reasonably matching each optical lens, the system structure is compact and reasonable, easy to assemble, low tolerance sensitivity, and more suitable for large-scale high yield production;

[0016] 3、The full glass structure has high stability, can compensate the focusing surface displacement well 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, so that the imaging system can also have high imaging quality at a large angle.

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

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

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

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

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

[0023] In the figure, STO is an optical stop, L1 is a first lens, L2 is a second lens, L3 is a third lens, L4 is a fourth lens, L5 is a fifth lens, L6 is a sixth lens, L7 is a seventh lens, L8 is a filter, L9 is an equivalent glass flat plate, and IMA is an imaging surface. DETAILED DESCRIPTION

[0024] It should be pointed out that the following detailed description is exemplary and is intended to provide further illustration 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 the scope of the example embodiments according to the present application is limited only by the appended claims. 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 seven-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, sixth lens and seventh lens along the light path incident direction, and a diaphragm is arranged between the third lens and the fourth lens; without considering the reverse curvature caused by the aspherical coefficient, the first lens is a double-concave negative lens, the object side surface is concave, and the image side surface is concave; the second lens is a double-convex positive lens, the object side surface is convex, and the image side surface is convex; the third lens is a double-convex positive lens, the object side surface is convex, and the image side surface is convex; the fourth lens is a double-convex positive lens, the object side surface is convex, and the image side surface is convex; the fifth lens is a double-concave negative lens, the object side surface is concave, and the image side surface is concave; the sixth lens is a meniscus positive lens, the object side surface is convex, and the image side surface is concave; the seventh lens is a meniscus negative lens, the object side surface is concave, and the image side surface is convex; all lenses are made of glass material, the first lens, the second lens, the third lens, the fourth lens, the fifth lens are glass spherical lenses, and the sixth lens and the seventh lens are aspherical lenses; the fourth lens and the fifth lens are tightly connected to form a cemented lens group.

[0027] The fourth lens and the fifth lens form an achromatic double-cemented lens, reasonable lens matching makes the optical system realize small volume, 4K, large aperture, day and night confocal, low temperature drift design, and at the same time, on-axis and off-axis aberrations are well corrected, and good imaging quality is achieved, 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, the sixth lens and the seventh lens are f1, f2, f3, f4, f5, f6 and f7 respectively, wherein f1, f2, f3, f4, f5, f6 and f7 satisfy the following ratios: -1.0 < f1 / f < 0.0, 1.0 < f2 / f < 2.0, 1.0 < f3 / f < 2.0, 0.0 < f4 / f < 1.0, -1.0 < f5 / f < 0.0, 1.0 < f6 / f < 2.0, and -2.0 < f7 / f < -1.0.

[0029] In the embodiment, the first lens satisfies the relationship: 1.7 ≤ N d ≤ 2.0, and Vd ≤ 50.0; the second lens satisfies the relationship: 1.7 ≤ N d ≤ 2.0, 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: 1.5 ≤ N d ≤ 1.8, V d ≥ 50.0; the fifth lens satisfies the relationship: 1.7 ≤ N d ≤ 2.0, V d ≤ 50.0; the sixth lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≤ 50.0; the seventh lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≤ 50.0; wherein N d is the refractive index, V d is the Abbe number.

[0030] In this embodiment, the air gap between the first lens and the second lens is 1.5-2.0 mm; the air gap between the second lens and the third lens is 0.1-0.5 mm; the air gap between the third lens and the diaphragm is 0.1-0.5 mm; the air gap between the diaphragm and the fourth lens is 0.1-0.5 mm; the fourth lens and the fifth lens are cemented lens groups, and the air gap is 0 mm; the air gap between the fifth lens and the sixth lens is 3.5-4.0 mm; the air gap between the sixth lens and the seventh lens is 2.5-3.0 mm.

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

[0032]

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

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

[0035]

[0036] In the embodiment, the total track 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 ≤1.5.

[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 seventh 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≤15.0mm;

[0042] (2) aperture F≤1.5;

[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 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 axial distance between each lens, etc., while meeting the 4K imaging performance requirements of the 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 seven-piece 4K forward-looking narrow-angle camera as described above, in which light rays are sequentially imaged after passing through the first lens, the second lens, the third lens, the diaphragm, the fourth lens, the fifth lens, the sixth lens, the seventh 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. Since there are too many values, it is impossible to enumerate them, therefore, the present application discloses some values to illustrate the technical solutions of the present application, and the above-mentioned enumerated 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), or as: non-detachably fixedly connected (for example, riveted, welded), 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, analogous or close to them, unless otherwise stated.

[0053] Any of the components provided by the present application can be assembled from multiple individual constituent parts, 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 obtain equivalent embodiments. However, any simple modification, equivalent change and modification of the above embodiments made without departing from the technical solution content 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 seven-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 direction of incidence of the light path as a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, a diaphragm is arranged between the third lens and the fourth lens, and the number of lenses with optical power in the camera is 7; the first lens is a double-concave negative lens; the second lens is a double-convex positive lens; the third lens is a double-convex positive lens; the fourth lens is a double-convex positive lens; the fifth lens is a double-concave negative lens; the sixth lens is a meniscus positive lens, the object side surface of which is a convex surface, and the image side surface of which is a concave surface; the seventh 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; all the lenses are made of glass material, wherein the sixth lens and the seventh lens are aspherical lenses, and the fourth lens and the fifth lens are tightly arranged 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, the sixth lens, and the seventh lens are f1, f2, f3, f4, f5, f6, and f7 respectively, wherein f1, f2, f3, f4, f5, f6, and f7 and f satisfy the following ratios: -1.0 < f1 / f < 0.0, 1.0 < f2 / f < 2.0, 1.0 < f3 / f < 2.0, 0.0 < f4 / f < 1.0, -1.0 < f5 / f < 0.0, 1.0 < f6 / f < 2.0, and -2.0 < f7 / f < -1.0; the air gap between the first lens and the second lens is 1.5-2.0 mm; the air gap between the second lens and the third lens is 0.1-0.5 mm; the air gap between the third lens and the diaphragm is 0.1-0.5 mm; the air gap between the diaphragm and the fourth lens is 0.1-0.5 mm; the fourth lens and the fifth lens form a cemented lens group, and the air gap is 0 mm; the air gap between the fifth lens and the sixth lens is 3.5-4.0 mm; the air gap between the sixth lens and the seventh lens is 2.5-3.0 mm; the total optical length TTL of the optical system and the focal length f of the optical system satisfy TTL / f ≤ 2.0; and the image height H of the optical system and the focal length f of the optical system satisfy H / f ≤ 1.

0.

2. The seven-piece 4K front-view narrow-angle camera of claim 1, wherein: The first lens satisfies the relationship: 1.7 ≤ N d ≤ 2.0, V d ≤ 50.0; the second lens satisfies the relationship: 1.7 ≤ N d ≤ 2.0, 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: 1.5 ≤ N d ≤ 1.8, V d ≥ 50.0; the fifth lens satisfies the relationship: 1.7 ≤ N d ≤ 2.0, V d ≤ 50.0; the sixth lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≤ 50.0; the seventh 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 seven-piece 4K front-view narrow-angle camera of claim 1, wherein: The F number of the optical system is ≤1.

5.

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

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

Images