An in-vehicle optical lens and an imaging device

Abstract

A vehicle-mounted optical lens includes a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens and an image plane arranged along the optical axis from the object side to the image side; the first lens is a negative-power spherical glass lens with a convex surface on the object side and a concave surface on the image side, the second lens is a positive-power plastic aspherical lens with a concave surface on the object side and a convex surface on the image side, the third lens is a positive-power glass spherical lens, the fourth lens is a biconvex positive-power glass spherical lens, and the fifth lens is a negative-power plastic aspherical lens; the second lens and the fifth lens are arranged as plastic aspherical lenses, so that the light rays in the outer field of view have a better incident state, enabling the lens to have a smaller volume while ensuring high resolution, and the third lens and the fourth lens both adopt lenses with positive focal length values, so that the lens has smaller chromatic aberration and thus better resolution, reducing the generation of lens ghosts.

Description

Technical Field

[0001] The present application relates to the field of optical imaging, and particularly to a vehicle-mounted optical lens and an imaging device. Background Art

[0002] Optical lenses play an important role in vehicle assisted driving systems. In particular, vehicle-mounted optical lenses are installed inside or outside the vehicle cab, and the images formed on the sensor through the lenses are used to monitor the conditions in front of the vehicle during driving. Vehicle-mounted lenses play an important role in autonomous driving systems. And for safety considerations, the optical lenses for vehicle applications have more stringent requirements for certain optical parameters, especially for the resolution performance of optical lenses, which is getting higher and higher.

[0003] A Chinese patent discloses a high-definition ultra-wide-angle lens (authorization announcement number: CN 205861988 U), which provides a high-definition ultra-wide-angle lens, including a first lens, a second lens, a diaphragm, a third lens, a fourth lens, a fifth lens and a filter arranged along the optical axis from the object side. The first lens is a meniscus spherical lens, the second lens is a meniscus aspherical lens, the third lens is a biconvex or plano-convex spherical lens, the fourth lens is a meniscus spherical lens, and the fifth lens is a meniscus aspherical lens.

[0004] For the requirements of high resolution, existing products of the same type adopt an all-glass structure, which is not conducive to meeting the requirements of miniaturization and low distortion of the lens, and has a high cost; or, like the above-mentioned prior art, adopt a glass-plastic hybrid structure, where the structure of the number of lenses and angles is complex, and the imaging effect is poor with serious ghost images. Summary of the Invention

[0005] To solve the problems raised in the above background art, the present application proposes a vehicle-mounted optical lens and an imaging device, which have the characteristics of simple structure and low cost, and achieve miniaturization of the structure while having high resolution.

[0006] The technical solution adopted by the present application is as follows:

[0007] A vehicle-mounted optical lens, characterized by including,

[0008] A first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens and an image plane arranged along the optical axis from the object side to the image side;

[0009] The first lens is a negative refractive power spherical glass lens with a convex object side and a concave image side, the second lens is a positive refractive power plastic aspherical lens with a concave object side and a convex image side, the third lens is a positive refractive power glass spherical lens, the fourth lens is a biconvex positive refractive power glass spherical lens, and the fifth lens is a negative refractive power plastic aspherical lens.

[0010] A filter is provided between the fifth lens and the image plane.

[0011] The focal length value F2 of the second lens and the focal length value F of the entire lens satisfy the following relationship: 10 ≥ F2 / F ≥ 2; the second lens satisfies the following relationship: 1.65 ≥ Nd2 ≥ 1.5, 60 ≥ Vd2 ≥ 40, where Nd2 is the refractive index of the second lens and Vd2 is the Abbe number of the second lens;

[0012] The focal length value F5 of the fifth lens and the focal length value F of the entire lens satisfy the following relationship: -1 ≥ F5 / F ≥ -4; the fifth lens satisfies the following relationship: 1.7 ≥ Nd5 ≥ 1.6, 40 ≥ Vd5 ≥ 18, where Nd5 is the refractive index of the fifth lens and Vd5 is the Abbe number of the fifth lens.

[0013] The vehicle-mounted optical lens satisfies the following relationship: H / D / FOV ≤ 0.025;

[0014] Wherein, H represents the maximum clear aperture of the convex surface of the first lens facing the object plane side, D represents the maximum image plane circle diameter of the imaging image plane, and FOV represents the field angle size corresponding to the maximum image plane circle diameter of the imaging image plane.

[0015] The focal length value of the first lens satisfies the following relationship: -1 ≥ F1 / F ≥ -3.5, where F1 is the focal length of the first lens and F is the focal length of the entire lens;

[0016] The first lens satisfies the following relationship: 1.9 ≥ Nd1 ≥ 1.6, 65 ≥ Vd1 ≥ 35, where Nd1 is the refractive index of the first lens and Vd1 is the Abbe number of the first lens.

[0017] The focal length value of the third lens satisfies the following relationship: 5 ≥ F3 / F ≥ 1, where F3 is the focal length of the third lens and F is the focal length of the entire lens;

[0018] The third lens satisfies the following relationship: 1.7 ≥ Nd3 ≥ 1.4, 85 ≥ Vd3 ≥ 45, where Nd3 is the refractive index of the third lens and Vd3 is the Abbe number of the third lens.

[0019] The focal length value of the fourth lens satisfies the following relationship: 4 ≥ F4 / F ≥ 1.5, where F4 is the focal length of the fourth lens and F is the focal length of the entire lens;

[0020] The fourth lens satisfies the following relationship: 1.7 ≥ Nd4 ≥ 1.4, 85 ≥ Vd4 ≥ 45, where Nd4 is the refractive index of the fourth lens and Vd4 is the Abbe number of the fourth lens.

[0021] The in-vehicle optical lens described above satisfies the following relationship: TTL / D ≥ 2;

[0022] Among them, TTL represents the distance from the vertex on the object surface side of the first lens to the image plane, and D represents the maximum image plane circle diameter of the imaging image plane.

[0023] The second lens and the fifth lens described above satisfy the aspheric definition equation:

[0024]

[0025] Among them, Z is the sagittal height along the optical axis direction, c represents the curvature corresponding to the radius, r is the radial coordinate, k is the conic quadratic curve constant, and A, B, C, D, E, F, G are aspheric coefficients.

[0026] An imaging device, characterized in that it includes an imaging element and the in-vehicle optical lens described in any one of claims 1-9, and the imaging element is used to convert the optical signal formed by the optical lens into an electrical signal.

[0027] Compared with the prior art, the advantages of the present application are that two plastic aspheric lenses, namely the second lens and the fifth lens, are provided, so that the incident state of the outer field light is better, and the lens has a smaller volume on the premise of ensuring a higher resolution.

[0028] Two glass spherical lenses, namely the third lens and the fourth lens, are provided, and the third lens and the fourth lens are separately arranged, so that the lens has smaller chromatic aberration and thus better resolution.

[0029] By controlling the curvature and shape of each lens, the generation of ghost images can be controlled and reduced.

[0030] During use, the object surface side of the first lens is exposed to the external environment. The first lens is made of glass material, which can make the exposed object surface side have better wear resistance and impact resistance, making it more suitable for the use requirements of in-vehicle lenses.

[0031] Both the third lens and the fourth lens are set as glass spherical lenses with positive optical power, and there is no defocusing at high and low temperatures, so that it does not defocus in the high and low temperature environment of -40°C to 105°C and still has good optical performance.

[0032] Through a reasonable optical structure and the use of two plastic lenses, the present invention has a smaller front aperture and a smaller lens length while ensuring a higher resolution, and produces less optical distortion and fewer ghost images. Description of the Drawings

[0033] The present application will be further described in detail below in conjunction with the accompanying drawings and preferred embodiments. However, those skilled in the art will appreciate that these drawings are only drawn for the purpose of explaining the preferred embodiments and should not be construed as limiting the scope of the present application. In addition, unless otherwise specified, the drawings are only schematic diagrams conceptually representing the composition or structure of the described object and may include exaggerated displays, and the drawings are not necessarily drawn to scale.

[0034] Figure 1 is a schematic optical structure diagram of an in-vehicle optical lens of the present invention;

[0035] Figure 2 is the optical distortion curve f - tan(θ) of an in-vehicle optical lens of the present invention;

[0036] Figure 3 is the resolution curve of an in-vehicle optical lens of the present invention at different angles.

[0037] In the figure: 1, the first lens; 2, the second lens; 3, the third lens; 4, the aperture stop; 5, the fourth lens; 6, the fifth lens; 7, the filter; 8, the optical axis; 9, the image plane. Detailed Embodiment

[0038] In order to enable those skilled in the art to better understand the technical solutions of the present disclosure, the present disclosure will be described in detail, clearly, and completely below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present disclosure and are not used to limit the present disclosure.

[0039] In the description of the present invention, if the first and the second are described only for the purpose of distinguishing technical features, they should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence of the indicated technical features.

[0040] Those skilled in the art should understand that in the disclosure of the present invention, the orientation or positional relationships indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting the present invention.

[0041] Embodiment 1

[0042] Please refer to Figure 1, in this embodiment, an in-vehicle optical lens is provided, which includes a first lens 1, a second lens 2, a third lens 3, a diaphragm 4, a fourth lens 5, a fifth lens 6 and an image plane 9 arranged along the optical axis 8 from the object side to the image side; the first lens 1 is a negative-power spherical glass lens with a convex surface on the object side and a concave surface on the image side, the second lens 2 is a positive-power plastic aspherical lens with a concave surface on the object side and a convex surface on the image side, the third lens 3 is a positive-power glass spherical lens, the fourth lens 5 is a biconvex positive-power glass spherical lens, and the fifth lens 6 is a negative-power plastic aspherical lens.

[0043] Both the third lens 3 and the fourth lens 5 adopt positive-power glass spherical lenses, which do not defocus at high and low temperatures and can still maintain excellent optical performance in the high and low temperature environment of -40°C to 105°C; the fourth lens 5 adopts a biconvex structure, which can converge the diverging light rays and appropriately compress them, so that the light ray trend transitions smoothly and enters the subsequent optical system smoothly, and can also further converge the light rays entering the subsequent optical system, which is beneficial to reducing the optical path of the subsequent light rays and realizing a shorter TTL.

[0044] The third lens 3 and the fourth lens 5 are separately arranged, so that they have good heat dissipation and heat resistance, and can maintain a stable diopter in a high temperature environment, and are more suitable for the in-vehicle environment.

[0045] Both the third lens 3 and the fourth lens 5 adopt biconvex positive-power lenses, which can further correct the aberration generated by the front lens group and further converge the light rays at the same time; by arranging the third lens 3 with positive power and the fourth lens 5 in front and the fifth lens 6 with negative power behind, it is beneficial to smoothly transition the light rays passing through the first lens 1 and the second lens 2 to the fifth lens 6 and reduce the overall length of the optical system.

[0046] The first lens 1 adopts a glass structure, and the surface close to the object side is set as a hyperbolic meniscus structure, and the surface close to the image side is set as an inward concave spherical structure; being set as the hyperbolic meniscus structure can collect large field-of-view light rays as much as possible, make the light rays enter the subsequent optical system, and increase the light passing amount. In practical applications, considering the in-vehicle lens outdoor installation and use environment, it will be in bad weather such as rain and snow. Such a meniscus shape design convex to the object side is beneficial to the sliding of water droplets and reduces the impact on imaging; and the surface of the first lens 1 convex to the object side is exposed to the external environment for a long time during use. Setting it as a glass structure can make it have better wear resistance and impact resistance, and can better meet the use requirements of in-vehicle lenses.

[0047] The second lens 2 and the fifth lens 6 are aspherical lenses made of plastic. The second lens 2 is a positive power lens with a concave object side and a convex image side. Lenses made of plastic have a relatively large coefficient of thermal expansion. When the ambient temperature of the lens changes significantly, the plastic lens will cause a large change in the optical back focus of the lens. The characteristic of an aspherical lens is that the curvature continuously changes from the center to the periphery of the lens. Different from a spherical lens with a constant curvature from the center to the periphery, an aspherical lens has better curvature radius characteristics and has the advantages of improving distortion aberration and astigmatism aberration. After using an aspherical lens, it is possible to better eliminate the aberration that appears during imaging, thereby improving the imaging quality of the lens. The setting of the aspherical lens helps to correct the system aberration and improve the resolution.

[0048] And through the second lens 2 set as an aspherical lens, the light passing through the first lens 1 can be smoothly transitioned to the third lens 3, reducing the total length of the optical system. Further, various aberrations of the optical system can be fully corrected, and on the premise of achieving a compact structure, the system resolution is further improved, and optical performance such as distortion and CRA is optimized.

[0049] In this application, by optimizing the shape of the lens, reasonably distributing the optical power, and appropriately setting the number of spherical and aspherical mirror surfaces, it is possible to achieve high-definition imaging while taking into account the miniaturization, small distortion, high resolution, low cost, and good temperature adaptability of the lens, meeting the usage requirements of in-vehicle lenses.

[0050] Embodiment 2

[0051] Please refer to Figure 1 , on the basis of Embodiment 1 of this application, another embodiment is provided.

[0052] The focal length value of the first lens 1 satisfies the following relationship: -1 ≥ F1 / F ≥ -3.5;

[0053] The focal length value of the second lens 2 satisfies the following relationship: 10 ≥ F2 / F ≥ 2;

[0054] The focal length value of the third lens 3 satisfies the following relationship: 5 ≥ F3 / F ≥ 1;

[0055] The focal length value of the fourth lens 5 satisfies the following relationship: 4 ≥ F4 / F ≥ 1.5;

[0056] The focal length value of the fifth lens 6 satisfies the following relationship: -1 ≥ F5 / F ≥ -4;

[0057] Where F1 is the focal length of the first lens 1, F2 is the focal length of the second lens 2, F3 is the focal length of the third lens 3, F4 is the focal length of the fourth lens 5, F5 is the focal length of the fifth lens 6, and F is the focal length of the entire lens.

[0058] The first lens 1 satisfies the following relationships: 1.9 ≥ Nd1 ≥ 1.6, 65 ≥ Vd1 ≥ 35;

[0059] The second lens 2 satisfies the following relationships: 1.65 ≥ Nd2 ≥ 1.5, 60 ≥ Vd2 ≥ 40;

[0060] The third lens 3 satisfies the following relationships: 1.7 ≥ Nd3 ≥ 1.4, 85 ≥ Vd3 ≥ 45;

[0061] The fourth lens 5 satisfies the following relationships: 1.7 ≥ Nd4 ≥ 1.4, 85 ≥ Vd4 ≥ 45;

[0062] The fifth lens 6 satisfies the following relationships: 1.7 ≥ Nd5 ≥ 1.6, 40 ≥ Vd5 ≥ 18.

[0063] Nd1 is the refractive index of the first lens 1, and Vd1 is the Abbe number of the first lens;

[0064] Nd2 is the refractive index of the second lens 2, and Vd2 is the Abbe number of the second lens;

[0065] Nd3 is the refractive index of the third lens 3, and Vd3 is the Abbe number of the third lens;

[0066] Nd4 is the refractive index of the fourth lens 5, and Vd4 is the Abbe number of the fourth lens;

[0067] Nd5 is the refractive index of the fifth lens 6, and Vd5 is the Abbe number of the fifth lens.

[0068] The optical lens described above satisfies the following relationship: TTL / D ≥ 2. Among them, TTL represents the total length of the imaging lens, that is, the distance from the vertex on the object side of the first lens 1 to the image plane 9, and D represents the diameter of the largest image plane circle of the imaging.

[0069] The optical lens described above also satisfies the following relationship: H / D / FOV ≤ 0.025. Among them, H represents the maximum clear aperture of the convex surface of the first lens 1 facing the object side, D represents the diameter of the largest image plane circle of the imaging, and FOV represents the field angle corresponding to the diameter of the largest image plane circle of the imaging.

[0070] Specifically, in the vehicle-mounted optical lens described above, the specific design parameters that satisfy the above relational expressions are:

[0071] Item EFL H D FOV TTL Parameter 2.66 mm 10 mm 6.6 mm 130° 19 mm

[0072] The lens structure with values within the above optical specifications can achieve the optical performance of this application. If the optical specifications exceed the above range, there will be a problem that the optical performance of this application cannot be achieved.

[0073] The second lens 2 and the fifth lens 6 are plastic aspherical lenses, the first lens 1, the third lens 3 and the fourth lens 5 are glass spherical lenses, and the plastic aspherical lenses satisfy the aspherical definition equation:

[0074]

[0075] where Z is the sag along the optical axis direction, c represents the curvature corresponding to the radius, r is the radial coordinate, k is the conic constant, and A, B, C, D, E, F, G are aspherical coefficients.

[0076] And the lens surfaces of the plastic aspherical lenses satisfy:

[0077] Surface c k A B C D E P2R1 -0.118 5.15 -2.00668E-03 -6.05540E-05 1.21245E-05 -1.40577E-06 8.18369E-08 P2R2 -0.189 -3.83 -2.99346E-03 1.51765E-04 -1.65664E-05 1.26914E-06 -4.13804E-08 P5R1 0.018 15 -5.19528E-03 1.43897E-03 -6.12408E-04 1.77703E-04 -1.93902E-05 P5R2 0.217 1.8 -4.15468E-03 1.05830E-03 -6.55703E-04 2.00097E-04 -2.08022E-05

[0078] where P2 is the second lens 2 and P5 is the fifth lens 6;

[0079] P2R1 represents the lens surface on the object side of the second lens 2, and P2R2 represents the lens surface on the image side of the second lens 2;

[0080] P5R1 represents the lens surface on the object side of the fifth lens 6, and P5R2 represents the lens surface on the image side of the fifth lens 6.

[0081] Embodiment III

[0082] Please refer to Figure 1 , on the basis of Embodiment I of the present application, another embodiment is provided. The present application further includes a filter 7; specifically, the filter 7 is an IR filter 7, which is used to block and filter infrared light while allowing visible light to pass through; the filter 7 is arranged between the fifth lens 6 and the image plane 9, and the remaining infrared light passing through after filtering is imaged on the image plane 9; arranged along the optical axis 8 from the object side to the image side along the optical axis 8 are: the first lens 1, the second lens 2, the third lens 3, the aperture stop 4, the fourth lens 5, the fifth lens 6, the filter 7 and the image plane 9. Preferably, a protective glass may also be included between the filter 7 and the image plane 9 to prevent the internal components (such as chips) of the optical lens from being damaged.

[0083] The aperture stop 4 is arranged between the third lens 3 and the fourth lens 5, which can effectively converge the light entering the optical system and reduce the aperture of the lenses of the optical system; after the aperture stop 4 is arranged, a fourth lens 5 with a positive optical power is also used, which can further correct the aberration generated by the front lens group, and at the same time converge the light beam again, which can not only increase the aperture of the lens, but also shorten the total length of the lens, making the optical system more compact, so that the optical system has a relatively short total length of the lens.

[0084] Other contents of Embodiment III may be the same as any of the above embodiments.

[0085] Embodiment 4

[0086] An imaging device includes an imaging element and the in-vehicle optical lens described above. The imaging element is configured to convert the optical signal formed by the optical lens into an electrical signal. Preferably, in this embodiment, the imaging element is an image sensor, and the image sensor can convert the optical image on image plane 9 into an electrical signal in a corresponding proportional relationship with the optical image. Light rays are incident on the lens from the mirror surface where G1R1 is located and are refracted inside the lens. After passing through surface P5R2 and IR filter 7, they are incident on image plane 9 of the image sensor. Thus, the object to be photographed on the object side is imaged on image plane 9 of the image sensor.

[0087] The above has introduced this application in detail. Specific examples are used in this article to elaborate on the principle and implementation manner of this application. The description of the above embodiments is only used to help understand this application and its core idea. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of this application, several improvements and modifications can still be made to this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. An in-vehicle optical lens, characterized in that, Including: A first lens (1), a second lens (2), a third lens (3), a diaphragm (4), a fourth lens (5), a fifth lens (6) and an image plane (9) arranged along the optical axis (8) from the object side to the image side; The first lens (1) is a negative refractive power spherical glass lens with a convex surface on the object side and a concave surface on the image side. The second lens (2) is a positive refractive power plastic aspherical lens with a concave surface on the object side and a convex surface on the image side. The third lens (3) is a positive refractive power glass spherical lens. The fourth lens (5) is a biconvex positive refractive power glass spherical lens. The fifth lens (6) is a negative refractive power plastic aspherical lens. The following relationship is satisfied between the focal length value F2 of the second lens (2) and the focal length value F of the entire lens: 10≥F2 / F≥2.

2. The vehicle-mounted optical lens according to claim 1, characterized in that, A filter (7) is provided between the fifth lens (6) and the image plane (9).

3. An in-vehicle optical lens according to claim 1, characterized in that The second lens (2) satisfies the following relationship: 1.65≥Nd2≥1.5, 60≥Vd2≥40, where Nd2 is the refractive index of the second lens (2), and Vd2 is the Abbe number of the second lens (2); The following relationship is satisfied between the focal length value F5 of the fifth lens (6) and the focal length value F of the entire lens: -1≥F5 / F≥-4; The fifth lens (6) satisfies the following relationship: 1.7≥Nd5≥1.6, 40≥Vd5≥18, where Nd5 is the refractive index of the fifth lens (6), and Vd5 is the Abbe number of the fifth lens (6).

4. An in-vehicle optical lens according to claim 1, characterized in that, The in-vehicle optical lens satisfies the following relationship: H / D / FOV≤0.025; Wherein, H represents the maximum clear aperture of the convex surface of the first lens (1) facing the object side, D represents the maximum image plane circle diameter of imaging, and FOV represents the size of the field of view corresponding to the maximum image plane circle diameter of imaging.

5. An in-vehicle optical lens according to claim 1, characterized in that, The focal length value of the first lens (1) satisfies the following relationship: -1≥F1 / F≥-3.5, Where F1 is the focal length of the first lens (1), and F is the focal length of the entire lens; The first lens (1) satisfies the following relationship: 1.9≥Nd1≥1.6, 65≥Vd1≥35, Where Nd1 is the refractive index of the first lens (1), and Vd1 is the Abbe number of the first lens (1).

6. The vehicle-mounted optical lens according to claim 1, wherein The focal length value of the third lens (3) satisfies the following relationship: 5≥F3 / F≥1, Where F3 is the focal length of the third lens (3), and F is the focal length of the entire lens; The third lens (3) satisfies the following relationship: 1.7≥Nd3≥1.4, 85≥Vd3≥45, Where Nd3 is the refractive index of the third lens (3), and Vd3 is the Abbe number of the third lens (3).

7. An in-vehicle optical lens according to claim 1, characterized in that, The focal length value of the fourth lens (5) satisfies the following relationship: 4≥F4 / F≥1.5, Where F4 is the focal length of the fourth lens (5), and F is the focal length of the entire lens; The fourth lens (5) satisfies the following relationship: 1.7≥Nd4≥1.4, 85≥Vd4≥45, Where Nd4 is the refractive index of the fourth lens (5), and Vd4 is the Abbe number of the fourth lens (5).

8. The vehicle-mounted optical lens according to claim 1, characterized in that, The in-vehicle optical lens described above satisfies the following relationship: TTL / D≥2; Wherein, TTL represents the distance from the vertex on the object side of the first lens (1) to the image plane (9), and D represents the maximum image plane circle diameter of imaging.

9. An in-vehicle optical lens according to claim 1, characterized in that, The second lens (2) and the fifth lens (6) satisfy the aspheric definition equation: ； Where Z is the sagittal height in the direction of the optical axis (8), c represents the curvature corresponding to the radius, r is the radial coordinate, k is the conic quadratic curve constant, and A, B, C, D, E, F, G are aspheric coefficients.

10. An imaging device, characterized in that, It includes an imaging element and the in-vehicle optical lens described in any one of claims 1-9, and the imaging element is used to convert the optical signal formed by the optical lens into an electrical signal.

Images