Miniaturized structure vehicle-mounted lens and imaging method thereof

Abstract

The invention relates to a vehicle-mounted lens with a miniaturized structure, an optical system of the lens is composed of a first lens, a second lens and a third lens which are sequentially arranged from left to right along a light incident light path, and a diaphragm is arranged in front of the first lens. Wherein the first lens is a glass spherical lens, and the second lens and the third lens are plastic aspheric lenses. The combined use of the plastic lens and the glass lens can effectively reduce the manufacturing cost and improve the temperature adaptability of the lens. By reasonably distributing parameters such as focal power, surface type, center thickness and air interval of each lens, 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] The application relates to a small-size structure vehicle-mounted lens and an imaging method thereof, and relates to the technical field of lenses. BACKGROUND

[0002] With the rapid iteration and popularization of intelligent driving, a driver monitoring system (DMS) has become a core component for ensuring driving safety, which realizes real-time collection of driver facial dynamics through a lens, instant identification and early warning of risks such as fatigue driving and distracted operation, and is a key defense line for avoiding accidents caused by human factors. According to industry data, nearly 20% of road traffic accidents worldwide are related to driver fatigue, and technical optimization of the DMS has important practical significance for reducing the accident rate.

[0003] However, the current DMS lens on the market generally has the problem of redundant size, and needs to occupy a larger space of the instrument panel or A-pillar during installation, which not only destroys the integrated beauty of the cabin design, but also may slightly block the driver's field of view due to the protruding structure. At the same time, the larger size makes it difficult to adapt to the layout of small-size cabins, and the compatibility for compact vehicles is poor, which greatly limits the popularization and application on different vehicles. Therefore, it is an urgent need to develop a small-size and low-protrusion DMS lens to adapt to the development trend of intelligent driving cabins and improve the practicality of products. SUMMARY

[0004] In view of the deficiencies of the prior art, the technical problem to be solved by the application is to provide a small-size structure vehicle-mounted lens and an imaging method thereof, which have a compact size while ensuring clear imaging.

[0005] In order to solve the above technical problems, the technical scheme of the application is as follows: a small-size structure vehicle-mounted lens, the optical system of the lens is composed of a first lens, a second lens and a third lens arranged in sequence from left to right along the light incident path, and a diaphragm is arranged before the first lens; without considering the reverse curvature caused by the aspherical coefficient, the first lens is a meniscus positive lens, the object side surface of which is a convex surface and the image side surface is a concave surface; the second lens is a meniscus positive lens, the object side surface of which is a concave surface and the image side surface is a convex surface; the third lens is a meniscus negative lens, the object side surface of which is a convex surface and the image side surface is a concave surface; the first lens is a glass spherical lens, and the second and third lenses are plastic aspherical lenses.

[0006] Preferably, the focal length of the optical system is set as f, and the focal lengths of the first lens, the second lens and the third lens are f1, f2 and f3 respectively, wherein f1, f2 and f3 satisfy the following proportions: 1.0 < f1 / f < 2.0, 0.0 < f2 / f < 1.0 and -2.0 < f3 / f < -1.0.

[0007] Preferably, 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: 1.4≤N d ≤1.7, V d ≥50.0; wherein N d is the refractive index, V d is the Abbe number.

[0008] Preferably, the axial distance between each lens satisfies the following relationships: the air gap between the diaphragm and the first lens is -0.5-0.0 mm; the air gap between the first lens and the second lens is 1.0-1.5 mm; and the air gap between the second lens and the third lens is 0.1-0.5 mm.

[0009] Preferably, the second and third lenses are both aspherical lenses, and the aspherical curve equation is expressed as:

[0010]

[0011] wherein z is the sag of the aspherical surface at a height of r along the optical axis; c is the paraxial curvature of the aspherical surface, r=1 / c; k is the conic constant; and α1, α2, α3, α4, α5, α6, α7, and α8 are all high-order coefficients.

[0012] 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.

[0013] Preferably, the F number of the optical system is ≤2.0.

[0014] Preferably, the image height H of the optical system and the focal length f of the optical system satisfy the relationship: H / f≥0.5.

[0015] Preferably, the rear side of the third lens is provided with a filter.

[0016] An imaging method of a miniaturized vehicle-mounted lens, which is performed according to the following steps: light rays are sequentially imaged after passing through a diaphragm, a first lens, a second lens, and a third lens.

[0017] Compared with the prior art, the application has the following beneficial effects: the miniaturized vehicle-mounted lens provided by the application adopts three optical lenses, which are composed of one glass spherical lens and two plastic aspherical lenses to form an imaging system. The production cost is effectively controlled by using low-cost plastic aspherical lenses, and the excellent stability of the glass lens is used to suppress temperature drift, so as to ensure the stability of the imaging quality of the lens in a high-temperature or low-temperature environment; the total length of the lens is less than 10 mm, and the outer diameter is less than 7 mm, so that the optical performance of the camera group is ensured, the overall size of the lens is reduced, and the aesthetic degree is improved.

[0018] The application will be further described in detail below in combination with the drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

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

[0020] Fig. 2 is an axial chromatic aberration graph of the full working waveband of the application;

[0021] Fig. 3 is a vertical axial chromatic aberration graph of the full working waveband of the application;

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

[0023] In the figure: STO-optical stop; L1-first lens; L2-second lens; L3-third lens; L4-first equivalent glass flat plate; L5-second equivalent glass flat plate; IMA-imaging surface. DETAILED DESCRIPTION

[0024] The application will be further described in detail below in combination with the drawings and specific embodiments.

[0025] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise defined, 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 belongs.

[0026] It should be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, they indicate the presence of a feature, step, operation, device, component and / or combination thereof.

[0027] As Figs. 1-4As shown, the embodiment provides a miniaturized structure vehicle-mounted lens, the optical system of the lens is composed of a first lens, a second lens and a third lens arranged in sequence from left to right along the light incident path, and a diaphragm is arranged in front of the first lens; without considering the reverse bending caused by the aspherical coefficient, the first lens is a meniscus positive lens, the object side is convex, and the image side is concave; the second lens is a meniscus positive lens, the object side is concave, and the image side is convex; the third lens is a meniscus negative lens, the object side is convex, and the image side is concave; the first lens is a glass spherical lens, and the second and third lenses are plastic aspherical lenses.

[0028] Among them, the plastic aspherical lens can effectively correct various aberrations such as spherical aberration and coma, while reducing the number of lenses used, and the glass spherical lens can effectively suppress the temperature drift of the lens; by reasonably distributing the parameters such as the focal power, surface shape, center thickness and air gap of each lens, the total length and radial size of the lens are effectively reduced under the premise of ensuring the imaging quality, and the miniaturization of the lens group is achieved.

[0029] In the embodiment of the application, the focal length of the optical system is f, and the focal lengths of the first lens, the second lens and the third lens are f1, f2 and f3 respectively, wherein f1, f2 and f3 satisfy the following proportions: 1.0 < f1 / f < 2.0, 0.0 < f2 / f < 1.0 and -2.0 < f3 / f < -1.0.

[0030] In the embodiment of the application, 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; and the third lens satisfies the relationship: 1.4 ≤ N d ≤ 1.7, V d ≥ 50.0; wherein N d is the refractive index, and V d is the Abbe number.

[0031] In the embodiment of the application, the on-axis distance between each lens satisfies the following relationship, the air gap between the diaphragm and the first lens is -0.5-0.0mm; the air gap between the first lens and the second lens is 1.0-1.5mm; and the air gap between the second lens and the third lens is 0.1-0.5mm.

[0032] In the embodiment of the application, the second and third lenses are aspherical lenses, and the aspherical curve equation expression is:

[0033]

[0034] Wherein, z is the height of the aspheric surface along the optical axis direction at the position of height r, the height from the vertex of the aspheric surface; c is the paraxial curvature of the aspheric surface, r=1 / c; k is the conic constant; alpha1, alpha2, alpha3, alpha4, alpha5, alpha6, alpha7, alpha8 are all high order coefficients.

[0035] 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.

[0036] In the embodiment of the present application, the F number of the optical system is ≤2.0.

[0037] 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≥0.5.

[0038] In the embodiment of the present application, the rear side of the third lens is provided with a filter.

[0039] An imaging method of a miniaturized vehicle-mounted lens is performed in the following steps: light rays are sequentially imaged after passing through an aperture, a first lens, a second lens and a third lens.

[0040] The technical indexes realized by the optical system of the embodiment are as follows:

[0041] (1) focal length: 5.0≤EFFL≤6.0mm;

[0042] (2) aperture F≤2.0;

[0043] (3) field of view angle: 2w≥60°;

[0044] (4) working waveband: short wave near-infrared waveband.

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

[0046]

[0047]

[0048] The aspheric coefficients of each aspheric lens of the optical system of the embodiment are as follows:

[0049]

[0050] The optical system of the embodiment realizes miniaturization of the lens group by reasonably distributing the optical power, surface shape, central thickness of each lens and the axial distance between each lens, etc., while meeting the imaging performance requirements of the lens, so that the total length of the lens is less than 10mm and the outer diameter is less than 7mm.

[0051] The above merely describes preferred embodiments of the present application, but is not intended to limit the present application to other forms, and any person skilled in the art can make changes or modifications to the above disclosed technical contents into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiments without departing from the technical solution content of the present application and 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 miniaturized vehicle-mounted lens, characterized in that: The optical system of the lens consists of a first lens, a second lens, and a third lens arranged sequentially from left to right along the incident light path, with an aperture stop in front of the first lens. Without considering the curvature caused by the aspherical coefficient, the first lens is a meniscus positive lens with a convex object-side surface and a concave image-side surface; the second lens is a meniscus positive lens with a concave object-side surface and a convex image-side surface; and the third lens is a meniscus negative lens with a convex object-side surface and a concave image-side surface. The first lens is a glass spherical lens, while the second and third lenses are plastic aspherical lenses.

2. The miniaturized automotive lens according to claim 1, characterized in that: Let the focal length of the optical system be f, and the focal lengths of the first lens, second lens, and third lens be f1, f2, and f3, respectively. The ratios of f1, f2, and f3 with f satisfy the following condition: 1.0 <f1 / f<2.0,0.0<f2 / f<1.0, -2.0 <f3 / f<-1.0。 3. The miniaturized automotive lens according to claim 1, characterized in that: 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: 1.4≤N d ≤1.7, V d ≥50.0; where N d V is the refractive index. d Let be Abbe's constant.

4. The miniaturized automotive lens according to claim 1, characterized in that: The axial distances between each lens satisfy the following relationship, and the air gap between the aperture stop and the first lens is: -0.5~0.0mm; the air gap between the first lens and the second lens is 1.0~1.5mm; the air gap between the second lens and the third lens is 0.1~0.5mm.

5. The miniaturized automotive lens according to claim 1, characterized in that: The second and third lenses are both aspherical lenses, and the equation for the aspherical curve is: Where z is the sag of the aspherical surface at a height of r along the optical axis from the vertex of the aspherical surface; c is the paraxial curvature of the aspherical surface, r = 1 / c; k is the conic constant; α1, α2, α3, α4, α5, α6, α7, and α8 are all higher-order coefficients.

6. The miniaturized automotive lens 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 ≤ 2.

0.

7. The miniaturized automotive lens according to claim 1, characterized in that: The F-number of the optical system is ≤2.

0.

8. The miniaturized automotive lens 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≥0.

5.

9. The miniaturized automotive lens according to claim 1, characterized in that: A filter is provided on the rear side of the third lens.

10. An imaging method for a miniaturized automotive lens as described in any one of claims 1-9, characterized in that, The following steps are performed: the light rays pass through the aperture, the first lens, the second lens, and the third lens in sequence to form an image.

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