Full-glass fixed-focus optical lens and working method thereof

Abstract

The invention relates to a full-glass fixed-focus optical lens and a working method thereof. The optical lens is composed of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens which are sequentially arranged in the light incidence direction. According to the invention, the focal power and the surface type of each lens, the central thickness of each lens, the axial distance between the lenses and the like are reasonably distributed, 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] This invention relates to an all-glass fixed-focus optical lens and its working method. Background Technology

[0002] With the rapid development of autonomous driving technology and Advanced Driver Assistance Systems (ADAS), automotive forward-looking lenses, as core optical components for environmental perception, play a crucial role in realizing functions such as Lane Departure Warning (LDW), Automatic Emergency Braking (AEB), pedestrian detection, and Traffic Sign Recognition (TSR). Automotive forward-looking lenses need to possess a wide field of view, high resolution, excellent low-light imaging capabilities, and strong light suppression performance to meet the high-precision image acquisition requirements of high-speed driving, complex urban road conditions, and diverse lighting conditions. The operating environment of automotive forward-looking lenses includes factors such as a wide temperature range, rain, snow, fog, haze, dust particles, and road vibrations. These factors require lenses to have excellent adaptability to ensure consistent optical performance over long-term use. Furthermore, as the automotive industry moves towards lightweight and modular design, forward-looking lenses need to maintain high optical performance while achieving miniaturization, low weight, and low power consumption to fit into the compact installation space at the front of the vehicle and reduce overall vehicle energy consumption. Existing automotive forward-looking lenses mostly adopt an all-glass multi-element design or a hybrid glass and plastic structure, but both have certain limitations. All-glass multi-element lenses offer excellent optical performance and environmental adaptability thanks to the high refractive index and thermal stability of glass. However, the large number of lenses results in high manufacturing costs, significant weight, and complex assembly, hindering mass production and lightweight design. Hybrid glass-plastic lenses reduce cost and weight by incorporating plastic aspherical lenses, but plastic materials are prone to thermal deformation or aging under high temperatures or prolonged UV exposure, leading to focal length drift, image blurring, or decreased transmittance, failing to meet automotive-grade durability requirements. These shortcomings have prompted the industry to seek a new optical structure that balances high performance, reliability, and cost by optimizing the combination of glass lenses and aspherical designs to meet the diverse needs of automotive front-view cameras in the era of autonomous driving. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the present invention provides an all-glass fixed-focus optical lens and its working method, which achieves clear imaging while having a small size and strong environmental adaptability.

[0004] The solution adopted by the present invention to solve the technical problem is: an all-glass fixed-focus optical lens: the optical lens is composed of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged sequentially along the incident direction of light, the fifth lens and the sixth lens being cemented together to form a cemented lens group, and an aperture stop being provided between the fourth lens and the fifth lens.

[0005] Furthermore, the first lens is a meniscus negative lens with a convex object-side surface and a concave image-side surface; the second lens is a biconcave negative lens with a concave object-side surface and a concave image-side surface; the third lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; the fourth lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; the fifth lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; the sixth lens is a meniscus negative lens with a concave object-side surface and a convex image-side surface; and the seventh lens is a meniscus positive lens with a convex object-side surface and a concave image-side surface.

[0006] Furthermore, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are spherical glass lenses, and the seventh lens is an aspherical glass lens.

[0007] Furthermore, the air gap between the first lens and the second lens is 4.0~4.5mm; the air gap between the second lens and the third lens is 0.5~1.0mm; the air gap between the third lens and the fourth lens is 3.0~3.5mm; the air gap between the fourth lens and the aperture stop is 2.0~2.5mm; the air gap between the aperture stop and the fifth lens is 0.0~0.5mm; and the air gap between the sixth lens and the seventh lens is 1.5~2.0mm.

[0008] Furthermore, the first lens satisfies the following relationships: 1.7≤Nd≤2.0, Vd≤50; the second lens satisfies the following relationship: 1.3≤Nd≤1.6, Vd≥50; the third lens satisfies the following relationship: 2.0≤Nd≤2.3, Vd≤50; the fourth lens satisfies the following relationship: 1.7≤Nd≤2.0, Vd≥50; the fifth lens satisfies the following relationship: 1.3≤Nd≤1.6, Vd≥50; the sixth lens satisfies the following relationship: 1.7≤Nd≤2.0, Vd≤50; and the seventh lens satisfies the following relationship: 1.7≤Nd≤2.0, Vd≤50; where Nd is the refractive index and Vd is the Abbe constant.

[0009] Furthermore, the focal length of the optical lens is 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: -2.0 <f1 / f<-1.0,-3.0<f2 / f<-2.0,3.0<f3 / f<4.0,2.0<f4 / f<3.0,1.0<f5 / f<2.0,-3.0<f6 / f<-2.0,6.0<f7 / f<7.0。

[0010] Furthermore, the equation for the aspherical lens curve of the seventh lens is expressed as follows: 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; and a1, a2, a3, a4, a5, a6, a7, and a8 are all higher-order coefficients.

[0011] Furthermore, the total optical length (TTL) of the optical lens and the focal length (f) of the optical lens satisfy the following condition: TTL / f ≤ 7.7.

[0012] Furthermore, the image height H of the optical lens and the focal length f of the optical lens satisfy the following condition: H / f≥1.1.

[0013] A working method of an all-glass fixed-focus optical lens: When light is incident, the light path sequentially enters the first lens, the second lens, the third lens, the fourth lens, the aperture stop, the fifth lens, the sixth lens, and the seventh lens, and finally forms an image on the image plane.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. Employing a seven-element optical system, consisting of six spherical glass lenses and one aspherical glass lens, the all-glass structure helps control temperature drift and enhances the stability of image quality under high and low temperature conditions. It also ensures the lens's resistance to harsh conditions such as chemical corrosion and ultraviolet radiation. The lens's total length is less than 31 mm, and its outer diameter is less than 14.1 mm, ensuring the optical performance of the camera assembly while reducing the overall size of the lens and improving its aesthetics. The seventh element is a glass aspherical lens, which balances aberrations across different fields of view, further enhancing the overall image quality.

[0015] 2. This lens has an imaging angle of more than 140 degrees and also has the advantages of high imaging clarity, large light aperture, and low tolerance sensitivity, which can more comprehensively monitor the scene outside the vehicle. 3. By rationally matching the various optical lenses, the system structure is compact and reasonable, easy to assemble, has low tolerance sensitivity, and is more suitable for large-scale high-yield production; 4. It uses six glass lenses in combination with one glass aspherical lens, which enhances environmental adaptability while ensuring image quality; 5. The chromatic aberration along each axis, the transverse chromatic aberration, and higher-order chromatic aberrations have been corrected to ensure that the imaging system can maintain high imaging quality even at large angles.

[0016] 6. It can provide good compensation for focal plane displacement at high and low temperatures and has adaptability to complex environments. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the optical structure of the present invention; Figure 2 This is the axial chromatic aberration diagram of the entire working band of the present invention; Figure 3 This is the transverse chromatic aberration diagram of the entire working band of the present invention; Figure 4 This is the field curvature distortion diagram of the entire working band of the present invention.

[0018] In the diagram: STO - aperture stop; L1 - first lens; L2 - second lens; L3 - third lens; L4 - fourth lens; L5 - fifth lens; L6 - sixth lens; L7 - seventh lens; IR - filter; CG - sensor protective glass; IMA - imaging plane. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0020] like Figure 1 As shown, an all-glass fixed-focus optical lens is provided: the optical lens consists of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged sequentially along the incident direction of light. The fifth lens and the sixth lens are cemented together to form a cemented lens group, and an aperture stop is provided between the fourth lens and the fifth lens.

[0021] In this embodiment, the first lens is a meniscus negative lens with a convex object-side surface and a concave image-side surface; the second lens is a biconcave negative lens with a concave object-side surface and a concave image-side surface; the third lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; the fourth lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; the fifth lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; the sixth lens is a meniscus negative lens with a concave object-side surface and a convex image-side surface; and the seventh lens is a meniscus positive lens with a convex object-side surface and a concave image-side surface.

[0022] In this embodiment, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are glass spherical lenses, and the seventh lens is a glass aspherical lens.

[0023] In this embodiment, the second lens is a spherical lens with negative optical power, which corrects optical system distortion while adjusting large-angle light. The fifth and sixth lenses form an achromatic cemented doublet, controlling chromatic aberration within a reasonable range in the visible light band. The seventh lens is an aspherical lens with positive optical power, adjusting light from each field of view to strike the sensor at a reasonable angle, correcting advanced aberrations, and improving edge image quality. This reasonable lens combination enables the optical system to achieve a small size, large field of view, large aperture, and low temperature drift design, while also providing good correction for on-axis and off-axis aberrations, resulting in good image quality. Figures 2 to 4 As shown.

[0024] In this embodiment, the air gap between the first lens and the second lens is 4.0~4.5mm; the air gap between the second lens and the third lens is 0.5~1.0mm; the air gap between the third lens and the fourth lens is 3.0~3.5mm; the air gap between the fourth lens and the aperture stop is 2.0~2.5mm; the air gap between the aperture stop and the fifth lens is 0.0~0.5mm; and the air gap between the sixth lens and the seventh lens is 1.5~2.0mm.

[0025] In this embodiment, the first lens satisfies the following relationship: 1.7≤Nd≤2.0, Vd≤50; the second lens satisfies the following relationship: 1.3≤Nd≤1.6, Vd≥50; the third lens satisfies the following relationship: 2.0≤Nd≤2.3, Vd≤50; the fourth lens satisfies the following relationship: 1.7≤Nd≤2.0, Vd≥50; the fifth lens satisfies the following relationship: 1.3≤Nd≤1.6, Vd≥50; the sixth lens satisfies the following relationship: 1.7≤Nd≤2.0, Vd≤50; and the seventh lens satisfies the following relationship: 1.7≤Nd≤2.0, Vd≤50; where Nd is the refractive index and Vd is the Abbe constant.

[0026] In this embodiment, the focal length of the optical lens is 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. The ratios of f1, f2, f3, f4, f5, f6, and f7 to f satisfy the following ratio: -2.0. <f1 / f<-1.0,-3.0<f2 / f<-2.0,3.0<f3 / f<4.0,2.0<f4 / f<3.0,1.0<f5 / f<2.0,-3.0<f6 / f<-2.0,6.0<f7 / f<7.0。

[0027] In this embodiment, the equation for the aspherical lens curve of the seventh lens is: 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; and a1, a2, a3, a4, a5, a6, a7, and a8 are all higher-order coefficients.

[0028] In this embodiment, the total optical length (TTL) of the optical lens and the focal length (f) of the optical lens satisfy the following condition: TTL / f ≤ 7.7.

[0029] In this embodiment, the image height H of the optical lens and the focal length f of the optical lens satisfy the following condition: H / f≥1.1.

[0030] In this embodiment, the F-number of the optical system is ≤1.7.

[0031] In this embodiment, a filter is provided on the rear side of the seventh lens.

[0032] The working method of an all-glass fixed-focus optical lens: When light is incident, the light path sequentially enters the first lens, the second lens, the third lens, the fourth lens, the aperture stop, the fifth lens, the sixth lens, and the seventh lens, and finally forms an image on the image plane. The technical specifications achieved by the optical system in this embodiment are as follows: (1) Focal length: 3.8≤EFFL≤4.2mm; (2) Aperture F≤1.7; (3) Field of view: 2w ≥ 140°; (4) Operating band: Visible light band.

[0033] To achieve the above design parameters, the specific design of the optical system adopted in this embodiment is shown in the table below: The aspherical coefficients of the aspherical lenses in the optical system of this embodiment are shown in the table below: The optical system in this embodiment achieves miniaturization of the lens assembly and reduces costs 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.

[0034] Unless otherwise stated, if any of the technical solutions disclosed in this invention specify a numerical range, then the disclosed numerical range is a preferred numerical range. Anyone skilled in the art should understand that the preferred numerical range is merely one among many feasible numerical values ​​that has a more obvious or representative technical effect. Because there are many numerical values, it is impossible to list them all. Therefore, this invention discloses only some numerical values ​​to illustrate the technical solutions of this invention. Furthermore, the numerical values ​​listed above should not constitute a limitation on the scope of protection of this invention.

[0035] If the terms "first" or "second" are used in this document to specify components, those skilled in the art should know that the use of "first" or "second" is merely for the purpose of distinguishing components in description, and unless otherwise stated, the above terms have no special meaning.

[0036] If this invention discloses or relates to mutually fixedly connected components or structural parts, then, unless otherwise stated, a fixed connection can be understood as: a detachable fixed connection (e.g., using bolts or screws), or a non-detachable fixed connection (e.g., riveting, welding). Of course, mutually fixed connections 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).

[0037] Furthermore, the orientations or positional relationships used in any of the technical solutions disclosed in this invention above to indicate positional relationships, such as "longitudinal," "lateral," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing this patent. They are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this patent. In addition, unless otherwise stated, the terms used to indicate shape in any of the technical solutions disclosed in this invention above include shapes that are similar to, close to, or approximate with it.

[0038] 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.

[0039] 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. An all-glass fixed-focus optical lens, characterized in that: The optical lens consists of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged sequentially along the incident direction of light. The fifth lens and the sixth lens are cemented together to form a cemented lens group, and an aperture stop is provided between the fourth lens and the fifth lens.

2. The all-glass fixed-focus optical lens according to claim 1, characterized in that: The first lens is a meniscus negative lens with a convex object-side surface and a concave image-side surface; the second lens is a biconcave negative lens with a concave object-side surface and a concave image-side surface; the third lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; the fourth lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; the fifth lens is a biconvex positive lens with a convex object-side surface and a convex image-side surface; the sixth lens is a meniscus negative lens with a concave object-side surface and a convex image-side surface; and the seventh lens is a meniscus positive lens with a convex object-side surface and a concave image-side surface.

3. The all-glass fixed-focus optical lens according to claim 1, characterized in that: The first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are glass spherical lenses, and the seventh lens is a glass aspherical lens.

4. The all-glass fixed-focus optical lens according to claim 1, characterized in that: The air gap between the first lens and the second lens is 4.0~4.5mm; the air gap between the second lens and the third lens is 0.5~1.0mm; the air gap between the third lens and the fourth lens is 3.0~3.5mm; the air gap between the fourth lens and the aperture stop is 2.0~2.5mm; the air gap between the aperture stop and the fifth lens is 0.0~0.5mm; and the air gap between the sixth lens and the seventh lens is 1.5~2.0mm.

5. The all-glass fixed-focus optical lens according to claim 1, characterized in that: The first lens satisfies the following relationship: 1.7≤Nd≤2.0, Vd≤50; the second lens satisfies the following relationship: 1.3≤Nd≤1.6, Vd≥50; the third lens satisfies the following relationship: 2.0≤Nd≤2.3, Vd≤50; the fourth lens satisfies the following relationship: 1.7≤Nd≤2.0, Vd≥50; the fifth lens satisfies the following relationship: 1.3≤Nd≤1.6, Vd≥50; the sixth lens satisfies the following relationship: 1.7≤Nd≤2.0, Vd≤50; and the seventh lens satisfies the following relationship: 1.7≤Nd≤2.0, Vd≤50; where Nd is the refractive index and Vd is the Abbe constant.

6. The all-glass fixed-focus optical lens according to claim 1, characterized in that: The focal length of the optical lens is f. 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. The ratios of f1, f2, f3, f4, f5, f6, and f7 to f satisfy the following ratio: -2.

0. <f1 / f<-1.0,-3.0<f2 / f<-2.0,3.0<f3 / f<4.0,2.0<f4 / f<3.0,1.0<f5 / f<2.0,-3.0<f6 / f<-2.0,6.0<f7 / f<7.0。 7. The all-glass fixed-focus optical lens according to claim 3, characterized in that: The equation for the aspherical lens curve of the seventh lens is as follows: 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; and a1, a2, a3, a4, a5, a6, a7, and a8 are all higher-order coefficients.

8. The all-glass fixed-focus optical lens according to claim 1, characterized in that: The total optical length (TTL) of the optical lens and the focal length (f) of the optical lens satisfy the following condition: TTL / f ≤ 7.

7.

9. The all-glass fixed-focus optical lens according to claim 1, characterized in that: The image height H of the optical lens and the focal length f of the optical lens satisfy the following condition: H / f≥1.

1.

10. A method for operating an all-glass fixed-focus optical lens, employing an all-glass fixed-focus optical lens as described in any one of claims 1-9, characterized in that: When light is incident, the light path sequentially enters the first lens, the second lens, the third lens, the fourth lens, the aperture, the fifth lens, the sixth lens, and the seventh lens, and finally forms an image on the image plane.

Images