A front-viewing narrow-angle camera and an imaging method thereof

Abstract

The application relates to a front-view narrow-angle camera, and an optical lens is sequentially composed of a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens, a sixth lens and a seventh lens from an object side to an image side. The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are all glass spherical lenses. By reasonably distributing the optical power, the surface type, the central thickness of each lens and the axial distance between each lens, clear imaging is realized, the full-glass spherical lens is adopted, the system has extremely high environmental stability and is low in cost.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of front view narrow-angle camera and its imaging method, it is related to lens technical field. BACKGROUND

[0002] In the process of vehicle driving, the information of surrounding environment is collected by sensor in real time by perception system, equivalent to the "eyes" of automatic driving car, can help car to realize similar to the observation ability of human driver same effect.In automatic driving vehicle, perception system is mainly composed of camera, millimeter wave radar, laser radar and other sensors.Sensor on vehicle is mainly divided into front view camera, surround view camera, rear view camera, side view camera and built-in camera according to installation position five categories.

[0003] Front view camera: mainly installed on front windshield, for realizing the visual perception and identification function of driving, according to function can be divided into front view main camera, front view narrow-angle camera and front view wide-angle camera.Front view narrow-angle camera: the main role of this camera is to identify targets such as traffic lights and pedestrians, generally select narrow-angle lens, can select 30 ° ~ 40 ° or so lens.As a kind of vehicle-mounted lens, the environment it needs to adapt is complex and changeable, which requires front view narrow-angle camera to have very high environmental stability. SUMMARY

[0004] In view of the deficiencies of the prior art, the technical problem to be solved by the present application is to provide a front view narrow-angle camera and its imaging method.

[0005] In order to solve the above technical problems, the technical scheme of the present application is: a front view narrow-angle camera, the optical system of the camera is composed of first lens, second lens, third lens, diaphragm, fourth lens, fifth lens, sixth lens and seventh lens arranged in order from left to right along the light incident path;without considering the reverse bending caused by aspherical coefficient, the first lens is a meniscus convex positive lens, the object side is convex, and the image side is concave;the second lens is a double convex positive lens, the object side is convex, and the image side is convex;the third lens is a double concave negative lens, the object side is concave, and the image side is concave;the fourth lens is a meniscus convex positive lens, the object side is concave, and the image side is convex;the fifth lens is a meniscus convex positive lens, the object side is convex, and the image side is concave;the sixth lens is a double convex positive lens, the object side is convex, and the image side is convex;the seventh lens is a meniscus concave negative lens, the object side is concave, and the image side is convex;all lenses are made of glass material, wherein the second and third lenses are cemented lens group.

[0006] Preferably, the focal length of the optical system is set as 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 set as 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 < 2.0, 0.0 < f2 / f < 1.0, -1.0 < f3 / f < 0.0, 1.0 < f4 / f < 2.0, 1.0 < f5 / f < 2.0, 1.0 < f6 / f < 2.0, and -1.0 < f7 / f < 0.0.

[0007] Preferably, the first lens satisfies the relationship: 1.7 ≤ N d ≤ 2.0, and V d ≤ 50.0; the second lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, and V d ≥ 50.0; the third lens satisfies the relationship: 1.7 ≤ N d ≤ 2.0, and V d ≤ 50.0; the fourth lens satisfies the relationship: 1.2 ≤ N d ≤ 1.5, and V d ≥ 50.0; the fifth lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, and V d ≥ 50.0; the sixth lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, and V d ≥ 50.0; and the seventh lens satisfies the relationship: 1.7 ≤ N d ≤ 2.0, and V d ≤ 50.0; wherein N d is the refractive index, and V d is the Abbe number.

[0008] Preferably, the on-axis distances between the lenses satisfy the following relationships: the air gap between the first lens and the second lens is 0.1-0.5 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 diaphragm is 1.1-1.5 mm; the air gap between the diaphragm and the fourth lens is 3.1-3.5 mm; the air gap between the fourth lens and the fifth lens is 0.1-0.5 mm; the air gap between the fifth lens and the sixth lens is 2.5-3.0 mm; and the air gap between the sixth lens and the seventh lens is 0.5-1.0 mm.

[0009] Preferably, the total optical length TTL of the optical system and the focal length f of the optical system satisfy the relationship: TTL / f ≤ 2.0.

[0010] Preferably, the F number of the optical system is ≤ 1.6.

[0011] Preferably, the image height H of the optical system and the focal length f of the optical system satisfy: H / f≤1.0.

[0012] Preferably, the rear side of the seventh lens is provided with a filter.

[0013] An imaging method of a front-view narrow-angle camera is performed in the following steps: light rays are sequentially imaged after passing through a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens.

[0014] Compared with the prior art, the present application has the following beneficial effects:

[0015] 1. The lens has an imaging angle of more than 30 degrees for an object, and has the advantages of high imaging clarity, large light aperture, low tolerance sensitivity, and good high-low temperature stability, etc. Meanwhile, the lens can monitor the scene in front of the vehicle and the distant scene more comprehensively.

[0016] 2. By reasonably matching the optical lenses, the system structure is compact and reasonable, easy to assemble, low in tolerance sensitivity, and more suitable for large-scale high-yield production.

[0017] 3. The all-glass spherical surface structure is adopted, which has high stability and low cost, and makes good compensation for the displacement of the focusing surface at high and low temperatures, so that the system has high adaptability to complex environments.

[0018] 4. The axial chromatic aberration, sagittal chromatic aberration, and high-order chromatic aberration are corrected, so that the imaging system can also have high imaging quality at a large angle.

[0019] The present application will be further described in detail below in combination with the drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0020] Fig. 1 is a schematic diagram of the optical structure of the present application;

[0021] Fig. 2 is an axial chromatic aberration diagram of the full working waveband of the present application;

[0022] Fig. 3 is a sagittal chromatic aberration diagram of the full working waveband of the present application;

[0023] Fig. 4 is a field curvature distortion diagram of the full working waveband of the present application;

[0024] In the figure: STO- light 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; IMA- imaging surface. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] 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.

[0027] 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.

[0028] like Figs. 1-4 As shown, this embodiment provides a forward-looking narrow-angle camera. The camera's optical system consists of a first lens, a second lens, a third lens, an aperture, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged sequentially from left to right along the incident light path. Without considering the curvature caused by aspherical coefficients, the first lens is a meniscus convex positive lens with a convex object-side surface and a concave image-side surface; the second lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; the third lens is a biconcave negative lens with a concave object-side surface and a concave image-side surface; the fourth lens is a meniscus convex positive lens with a concave object-side surface and a convex image-side surface; the fifth lens is a meniscus convex positive lens with a convex object-side surface and a concave image-side surface; the sixth lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; and the seventh lens is a meniscus concave negative lens with a concave object-side surface and a convex image-side surface. All lenses are made of glass, and the second and third lenses are cemented lens groups. While achieving clear imaging, the system also exhibits extremely high environmental stability due to its all-glass spherical lens structure.

[0029] In this embodiment of the invention, the focal length of the optical system is set to 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: 1.0 <f1 / f<2.0,0.0<f2 / f<1.0,-1.0<f3 / f<0.0,1.0<f4 / f<2.0,1.0<f5 / f<2.0,1.0<f6 / f<2.0,-1.0<f7 / f<0.0。

[0030] In the embodiment of the present application, the first lens satisfies the relationship: 1.7≤N d ≤2.0, 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: 1.7≤N d ≤2.0, V d ≤50.0; the fourth lens satisfies the relationship: 1.2≤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; the seventh lens satisfies the relationship: 1.7≤N d ≤2.0, V d ≤50.0; wherein N d is the refractive index, and V d is the Abbe number.

[0031] In the embodiment of the present application, the axial distance between each lens satisfies the following relationship, the air gap between the first lens and the second lens is: 0.1-0.5mm; the second lens and the third lens are cemented lens groups, the air gap is 0mm; the air gap between the third lens and the stop is: 1.1-1.5mm; the air gap between the stop and the fourth lens is: 3.1-3.5mm; the air gap between the fourth lens and the fifth lens is: 0.1-0.5mm; the air gap between the fifth lens and the sixth lens is: 2.5-3.0mm; the air gap between the sixth lens and the seventh lens is: 0.5-1.0mm.

[0032] In the embodiment of the present application, the total optical length TTL of the optical system and the focal length f of the optical system satisfy: TTL / f≤2.0.

[0033] In the embodiment of the present application, the F number of the optical system is ≤1.6.

[0034] In the embodiment of the present application, the image height H of the optical system and the focal length f of the optical system satisfy: H / f≤1.0.

[0035] In the embodiment of the present application, the stop of the optical system is located behind the third lens.

[0036] In the embodiment of the present application, the rear side of the seventh lens is provided with a filter.

[0037] An imaging method of a front-view narrow-angle camera is performed in the following steps: light rays are sequentially imaged after passing through a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens.

[0038] In the embodiment of the present application, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are all glass spherical lenses. Through reasonable lens matching, the optical system realizes small size, large aperture, day and night confocal, low temperature drift design, and simultaneously well corrects on-axis and off-axis aberrations, has good imaging quality and high environmental stability, as shown in Figs. 2 to 4 .

[0039] The technical indexes realized by the optical system of the embodiment are as follows:

[0040] (1) focal length: 15.0≤EFFL≤16.0mm;

[0041] (2) aperture F≤1.6;

[0042] (3) field of view angle: 2w≥30°;

[0043] (4) working waveband: visible light waveband.

[0044] To realize the above design parameters, the specific design adopted by the optical system of the embodiment is shown in the following table:

[0045]

[0046]

[0047] The optical system of the embodiment realizes clear imaging while having high environmental stability by reasonably distributing the focal power and surface shape of each lens, the center thickness of each lens and the on-axis distance between each lens, and using all glass spherical lenses.

[0048] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application in other forms. Any skilled person in the art can modify or change the above-mentioned technical content into equivalent embodiments. However, any simple modification, equivalent change and modification made according to the technical essence of the present application to the above embodiments, without departing from the technical solution of the present application, still falls within the protection scope of the present application.

Claims

1. A front-facing narrow angle camera, characterized by: The optical system of the camera is composed of a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens, a sixth lens and a seventh lens arranged in sequence along the light path of the incident light from left to right; without considering the reverse bending caused by the aspherical surface coefficient, the first lens is a meniscus convex positive lens, the object side surface of which is convex and the image side surface of which is concave; the second lens is a double convex positive lens, the object side surface of which is convex and the image side surface of which is convex; the third lens is a double concave negative lens, the object side surface of which is concave and the image side surface of which is concave; the fourth lens is a meniscus convex positive lens, the object side surface of which is concave and the image side surface of which is convex; the fifth lens is a meniscus convex positive lens, the object side surface of which is convex and the image side surface of which is concave; the sixth lens is a double convex positive lens, the object side surface of which is convex and the image side surface of which is convex; the seventh lens is a meniscus concave negative lens, the object side surface of which is concave and the image side surface of which is convex; all the lenses are made of glass material, wherein the second lens and the third lens constitute a cemented lens group; the number of lenses with optical power in the camera is seven; the focal length of the optical system is set as 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 proportions: 1.0 < f1 / f < 2.0, 0.0 < f2 / f < 1.0, -1.0 < f3 / f < 0.0, 1.0 < f4 / f < 2.0, 1.0 < f5 / f < 2.0, 1.0 < f6 / f < 2.0 and -1.0 < f7 / 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 F number of the optical system is ≤ 1.6; the image height H of the optical system and the focal length f of the optical system satisfy: H / f ≤ 1.

0.

2. The forward looking 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: 1.5 ≤ N d ≤ 1.8, V d ≥ 50.0; the third lens satisfies the relationship: 1.7 ≤ N d ≤ 2.0, V d ≤ 50.0; the fourth lens satisfies the relationship: 1.2 ≤ 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; the seventh lens satisfies the relationship: 1.7 ≤ N d ≤ 2.0, V d ≤ 50.0; wherein N d is the refractive index, and V d is the Abbe number.

3. The forward looking narrow angle camera of claim 1, wherein: The on-axis distance between each lens satisfies the following relationship: the air gap between the first lens and the second lens is 0.1-0.5 mm; the second lens and the third lens constitute a cemented lens group, and the air gap is 0 mm; the air gap between the third lens and the diaphragm is 1.1-1.5 mm; the air gap between the diaphragm and the fourth lens is 3.1-3.5 mm; the air gap between the fourth lens and the fifth lens is 0.1-0.5 mm; the air gap between the fifth lens and the sixth lens is 2.5-3.0 mm; and the air gap between the sixth lens and the seventh lens is 0.5-1.0 mm.

4. The forward looking narrow angle camera of claim 1, wherein: The rear side of the seventh lens is provided with a filter.

5. A method of imaging for a forward looking narrow angle camera as claimed in any one of claims 1-4, characterized in that, The 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 and the seventh lens.

Images