A small DMS optical lens

Abstract

The present application relates to a kind of small DMS optical lens, and the optical system of lens is sequentially arranged by first lens, second lens, third lens and fourth lens from left to right along the light path of light incidence, first lens is meniscus positive lens, second lens is meniscus positive lens, third lens is meniscus positive lens, and fourth lens is meniscus negative lens, first lens is glass aspheric lens, second lens, third lens and fourth lens are plastic aspheric lens.The present application adopts four optical lenses, and the optical system is formed by one glass aspheric lens and three plastic aspheric lenses, while meeting the imaging performance requirements of lens, the total length of lens and the radial dimension of each lens are reduced, to achieve the miniaturization of lens group;In addition, a glass aspheric lens is arranged in the first to fourth lens of lens, which can further improve the overall image quality of lens, control temperature drift and improve the influence of high temperature or low temperature on the image quality of lens.

Description

Technical fields:

[0001] This invention belongs to the field of lens technology, and in particular relates to a small DMS optical lens. Background technology:

[0002] Currently, most mass-produced autonomous driving systems can only operate under specific conditions, requiring drivers to take over in many situations. Therefore, when drivers over-rely on autonomous driving and relinquish or weaken their control over the driving process, accidents may occur. The introduction of driver monitoring systems (DMS) can effectively reduce such situations. DMS systems are mostly based on facial recognition and eye-tracking technology using cameras, with primary functions including fatigue detection, distraction detection, and dangerous behavior detection. These cameras are installed facing the driver, including in the rearview mirror, dashcam, steering wheel, center console screen, and A-pillar. However, existing cameras are too large, hindering lens integration and affecting interior aesthetics. Summary of the Invention:

[0003] The present invention addresses the problems existing in the prior art. Specifically, the technical problem to be solved by the present invention is to provide a small DMS optical lens that is reasonably designed and has a small size while achieving clear imaging.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: a small DMS optical lens, wherein the optical system of the lens consists of a first lens, a second lens, a third lens, and a fourth lens arranged sequentially from left to right along the incident light path. The first lens is a meniscus positive lens, the second lens is a meniscus positive lens, the third lens is a meniscus positive lens, and the fourth lens is a meniscus negative lens. The first lens is a glass aspherical lens, and the second, third, and fourth lenses are all plastic aspherical lenses.

[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 concave, and the image-side surface is convex; and the object-side surface of the fourth lens is convex, and the image-side surface is concave.

[0006] Furthermore, the air gap between the first lens and the second lens is 0.1 to 0.5 mm; the air gap between the second lens and the third lens is 0.5 to 1.0 mm; and the air gap between the third lens and the fourth lens is 0.0 to 0.5 mm.

[0007] Furthermore, the focal length of the optical system is f, and the focal lengths of the first lens, second lens, third lens, and fourth lens are f1, f2, f3, and f4, respectively, where f1, f2, f3, and f4 satisfy the following ratio with f: 1.0 <f1 / f<2.0,1.0<f2 / f<2.0,3.0<f3 / f<4.0,-3.0<f4 / f<-2.0。

[0008] Furthermore, 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: 1.5≤N d ≤1.8, V d ≥50.0; where N d V is the refractive index. d Let be Abbe's constant.

[0009] Furthermore, the equations for the aspherical curves of the first lens, second lens, third lens, and fourth lens are as follows:

[0010]

[0011] 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.

[0012] 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 ≤ 1.5.

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

[0014] 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.

[0015] Furthermore, the aperture of the optical system is located on the object side of the first lens.

[0016] Compared with the prior art, the present invention has the following advantages: The present invention is reasonably designed and uses four optical lenses, consisting of one glass aspherical lens and three plastic aspherical lenses to form an optical system. While meeting the lens imaging performance requirements, it reduces the overall length of the lens and the radial dimensions of each lens, thus achieving lens miniaturization. In addition, the lens has a glass aspherical lens in the first to fourth lenses, which can further improve the overall image quality of the lens, control temperature drift, and improve the impact of high or low temperatures on the image quality of the lens. Attached image description:

[0017] Figure 1 This is a schematic diagram of the optical structure according to an embodiment of the present invention;

[0018] Figure 2 This is an axial chromatic aberration diagram of the entire working band of this invention.

[0019] Figure 3 This is a cross-axis chromatic aberration diagram of the entire working band of this invention.

[0020] Figure 4 This is a field curvature distortion diagram of the entire working band according to an embodiment of the present invention.

[0021] In the picture:

[0022] L1 - First lens; L2 - Second lens; L3 - Third lens; L4 - Fourth lens; L5 - Equivalent glass plate; IMA - Imaging plane; STO - Aperture stop. Detailed implementation method:

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0024] like Figure 1 As shown, this invention discloses a small DMS optical lens. The optical system of the lens consists of a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4 arranged sequentially from left to right along the incident light path. 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; the third lens is a meniscus positive lens with a concave object-side surface and a convex image-side surface; and the fourth lens is a meniscus negative lens with a convex object-side surface and a concave image-side surface. The lenses are made of glass and plastic materials, wherein the first lens is a glass aspherical lens, and the second, third, and fourth lenses are all plastic aspherical lenses.

[0025] In this embodiment, 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 air gap between the second lens and the third lens is 0.5–1.0 mm; and the air gap between the third lens and the fourth lens is 0.0–0.5 mm. Reducing the distance between the lenses while meeting imaging requirements is beneficial for the overall optical length of the lens and ensures miniaturization.

[0026] In this embodiment, the focal length of the optical system is f, and the focal lengths of the first lens, second lens, third lens, and fourth lens are f1, f2, f3, and f4, respectively, wherein f1, f2, f3, and f4 satisfy the following ratio with f: 1.0 <f1 / f<2.0,1.0<f2 / f<2.0,3.0<f3 / f<4.0,-3.0<f4 / f<-2.0。

[0027] In this embodiment, 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: 1.5≤N d ≤1.8, V d ≥50.0; where N d V is the refractive index. d Let be Abbe's constant.

[0028] In this embodiment, the equations for the aspherical curves of the first lens, the second lens, the third lens, and the fourth lens are as follows:

[0029]

[0030] 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.

[0031] The aspherical coefficients of the aspherical lenses in the optical system of this embodiment are shown in the table below:

[0032]

[0033] In this embodiment, the total optical length TTL of the optical system and the focal length f of the optical system satisfy the following condition: TTL / f≤1.5.

[0034] In this embodiment, the F-number of the optical system is ≤2.0.

[0035] In this embodiment, 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.

[0036] In this embodiment, the aperture stop STO of the optical system is located on the object side of the first lens L1.

[0037] In this embodiment, an equivalent glass plate L5 (i.e., a filter) is provided on the rear side of the fourth lens.

[0038] In this embodiment, the total length of the lens is less than 6 mm and the outer diameter is less than 6 mm.

[0039] In this embodiment, by rationally allocating the optical power, surface shape, center thickness of each lens, and on-axis distance between each lens, the overall length of the lens and the radial dimensions of each lens are reduced while meeting the lens imaging performance requirements, thus achieving lens miniaturization.

[0040] In this embodiment, the technical specifications achieved by the optical system are as follows:

[0041] (1) Focal length: 4.0≤EFFL≤5.0mm;

[0042] (2) Aperture F≤2.0;

[0043] (3) Field of view: 2w ≥ 60°;

[0044] (4) Operating band: shortwave infrared band.

[0045] To achieve the above design parameters, the specific design of the optical system adopted in this embodiment is shown in the table below:

[0046]

[0047] In this embodiment, as Figures 2 to 4 As shown, by using appropriate lens combinations, various aberrations in the system are effectively optimized, thus improving image quality.

[0048] In this embodiment, the optical system achieves miniaturization of the lens assembly 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.

[0049] The advantages of this invention are as follows: It employs four optical lenses, consisting of one glass aspherical lens and three plastic aspherical lenses to form the imaging system. The use of plastic aspherical lenses, which are significantly cheaper than glass lenses, reduces production costs while maintaining image quality. The total lens length and outer diameter are less than 6 mm, ensuring the optical performance of the camera assembly while reducing the overall size of the lens and improving aesthetics. Furthermore, incorporating a glass aspherical lens in the first to fourth lens elements further enhances the overall image quality, controls temperature drift, and mitigates the impact of high or low temperatures on image quality.

[0050] If this invention discloses or relates to components or structural parts that are fixedly connected to each other, then, unless otherwise stated, a fixed connection can be understood as: a fixed connection that can be detached (e.g., using bolts or screws), or a fixed connection that cannot be detached (e.g., riveting, welding). Of course, a fixed connection can also be replaced by an integral structure (e.g., manufactured in one piece using a casting process) (except where it is obviously impossible to use an integral molding process).

[0051] 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.

[0052] 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.

[0053] 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 DMS optical lens, characterized in that: The optical system of the lens consists of a first lens, a second lens, a third lens, and a fourth lens arranged in sequence from left to right along the light incident optical path. The first lens is a meniscus positive lens, the second lens is a meniscus positive lens, the third lens is a meniscus positive lens, and the fourth lens is a meniscus negative lens. The first lens is a glass aspherical lens, and the second, third, and fourth lenses are all plastic aspherical lenses. 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 concave, and the image side surface is convex. The object side surface of the fourth lens is convex, and the image side surface is concave. The air gap between the first lens and the second lens is 0.1 mm to 0.5 mm. The air gap between the second lens and the third lens is 0.5 mm to 1.0 mm. The air gap between the third lens and the fourth lens is 0.0 mm to 0.5 mm. The focal length of the optical system is f, and the focal lengths of the first, second, third, and fourth lenses are f1, f2, f3, and f4 respectively, where f1, f2, f3, and f4 satisfy the following ratios with f: 1.0 < f1 / f < 2.0, 1.0 < f2 / f < 2.0, 3.0 < f3 / f < 4.0, -3.0 < f4 / f < -2.

0. The total optical length TTL of the optical system and the focal length f of the optical system satisfy: TTL / f ≤ 1.

5.

2. A miniature DMS optical 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: 1.5≤N d ≤1.8, V d ≥50.0; The fourth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; where N d V is the refractive index. d Let be Abbe's constant.

3. A miniature DMS optical lens according to claim 1, characterized in that: The expressions of the aspheric curve equations of the first lens, the second lens, the third lens, and the fourth lens are: 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, r=1 / c; k is the conic constant; a1, a2, a3, a4, a5, a6, a7, and a8 are all coefficients of higher-order terms.

4. A miniature DMS optical lens according to claim 1, characterized in that: The F-number of the optical system ≤ 2.

0.

5. A miniature DMS optical 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: H / f ≥ 1.

0.

6. A miniature DMS optical lens according to claim 1, characterized in that: The aperture stop of the optical system is located on the object side surface of the first lens.

Images