Thermally-stable large-target-surface AVM optical imaging system

Abstract

The utility model discloses a thermal-stability large-target-surface AVM optical imaging system, which relates to the technical field of optical systems and vehicle-mounted imaging devices and sequentially comprises a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens, a sixth lens, an optical filter, protective glass and an image surface from an object surface to an image surface along an optical axis. The object plane side of the first lens is a convex surface, and the image plane side is a concave surface. The object surface side of the second lens is a convex surface, and the image surface side is a concave surface; the object plane side of the third lens is a convex surface, and the image plane side is a convex surface; the object plane side of the fourth lens is a convex surface, and the image plane side is a convex surface; the object plane side of the fifth lens is a concave surface, and the image plane side is a convex surface; the object plane side of the sixth lens is a convex surface, and the image plane side is a convex surface; wherein the fourth lens and the fifth lens form a group of glued lenses. According to the thermal-stability large-target-surface AVM optical imaging system, the visual field covers almost the surrounding environment of the whole vehicle, the visual field blind area is small, and the panoramic top view around the vehicle body and the parking auxiliary function can be better provided.

Description

Technical Field

[0001] This utility model relates to the technical field of optical systems and vehicle-mounted imaging devices, specifically, a thermally stable large-target-area AVM optical imaging system. Background Technology

[0002] The AVM (Around View Monitor) system is an intelligent driver assistance system that generates panoramic images by capturing images with multiple ultra-wide-angle fisheye lenses and processing them specially. It provides the driver with a panoramic overhead view of the vehicle's surroundings and parking assistance functions. This system plays a crucial role in enhancing driving safety and convenience and is expected to play an even greater role in the field of intelligent driving.

[0003] In the future, with continuous technological advancements and cost reductions, AVM systems are expected to be applied in more types of vehicles. However, most existing AVM lenses suffer from a relatively small field of view, which limits the comprehensiveness of monitoring the vehicle's surroundings. Furthermore, the target surface size that the lenses can match is also relatively small, which to some extent affects image clarity and detail capture capabilities. Utility Model Content

[0004] This invention proposes a thermally stable large-area AVM optical imaging system, which features ultra-wide angle, large target area, purple fringing optimization, and the ability to maintain stable imaging without refocusing when the outside temperature of the vehicle changes significantly.

[0005] The above-mentioned technical objective of this utility model is achieved through the following technical solution: a thermally stable large target surface AVM optical imaging system, which includes, along the optical axis from the object plane to the image plane, the following components in sequence: a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, a sixth lens, a filter, a protective glass, and an image plane;

[0006] The first lens has a convex surface on the object side and a concave surface on the image side;

[0007] The second lens has a convex surface on the object side and a concave surface on the image side;

[0008] The third lens has a convex surface on both the object plane and the image plane sides;

[0009] The fourth lens has a convex surface on both the object plane and the image plane sides;

[0010] The fifth lens has a concave surface on the object plane side and a convex surface on the image plane side;

[0011] The object plane side of the sixth lens is convex, and the image plane side is also convex.

[0012] The fourth and fifth lenses form a set of cemented lenses;

[0013] And it satisfies the following relationship:

[0014] 4.6<|f1 / f|<5.1; 2.5<|f2 / f|<3.1; 3.4<|f3 / f|<3.9; 11 .5<|f4 / f|<12.1; 33.1<|f5 / f|<33.7; 3.4<|f6 / f|<3.9;

[0015] Where f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f6 is the focal length of the sixth lens, and f is the effective focal length of the entire optical system.

[0016] In some embodiments, the Abbe constant Vd2 of the second lens, the Abbe constant Vd4 of the fourth lens, and the Abbe constant Vd6 of the sixth lens are all greater than 51 and less than 59.

[0017] In some embodiments, the maximum field of view (FOV) of the optical system satisfies the following condition:

[0018] FOV ≥ 210°.

[0019] In some embodiments, the maximum holoimage height of the optical system satisfies the following condition:

[0020] IHmax≥5.78mm.

[0021] In some embodiments, the effective focal length f of the optical system satisfies the following condition:

[0022] 1.3mm≤f≤1.45mm.

[0023] In some embodiments, the first lens is meniscus-shaped and has a negative optical power;

[0024] The second lens is concave-convex, with the object side being convex and the image side being concave, and its optical power is negative.

[0025] The third lens is biconvex, with a convex surface on the object side and a convex surface on the image side, and its optical power is positive.

[0026] The fourth lens is biconvex, with a convex surface on the object side and a convex surface with a plateau on the image side, and its optical power is negative.

[0027] The fifth lens is concave-convex, with the object side being concave and the image side being convex, and its optical power is positive.

[0028] The sixth lens is biconvex, with both the object plane and image plane sides being convex, and its optical power is positive.

[0029] In some embodiments, the aperture stop is disposed between the third lens and the fourth lens.

[0030] In summary, this utility model has the following beneficial effects:

[0031] Ultra-wide field of view (FOV) ≥ 210°: The field of view covers almost the entire environment around the vehicle, reducing blind spots and providing a better panoramic overhead view of the vehicle's surroundings and parking assistance functions.

[0032] Large target area: IHmax≥5.78mm. The larger the target area, the larger the chip size that can be matched, and the more types of chips that can be selected, thus meeting the diverse needs of the market.

[0033] Edge optimization with purple fringing: The lens group uses multiple plastic aspherical lenses, which are reasonably matched to reduce color difference at the image edges, especially the purple fringing phenomenon. This is beneficial for the stitching of the AVM system images and can provide the driver with a better 360° panoramic image of the vehicle's surroundings.

[0034] Thermal offset stabilization: When the outside temperature changes significantly, the image remains stable without refocusing, and the image quality will not degrade due to temperature changes. Attached Figure Description

[0035] Figure 1 A schematic diagram of the optical system provided in an embodiment of this utility model;

[0036] Figure 2 MTF analysis diagram of the optical system provided in the embodiment of this utility model;

[0037] Figure 3 A defocus curve of the optical system provided in this embodiment of the present invention at 20°C;

[0038] Figure 4 A defocus curve of the optical system provided in this embodiment of the present invention at -40°C;

[0039] Figure 5 A defocusing curve of the optical system provided in this embodiment of the present invention at 85°C;

[0040] Figure 6 Field curvature curve of the optical system provided in this embodiment of the utility model;

[0041] Figure 7 Standard dot matrix diagram provided for embodiments of this utility model; Detailed Implementation

[0042] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0043] In the description of this utility model, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not 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 utility model.

[0044] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0045] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0046] like Figure 1 As shown, this embodiment provides a thermally stable large-target AVM optical imaging system, which includes, along the optical axis from the object plane to the image plane, the following components in sequence: a first lens E1, a second lens E2, a third lens E3, an aperture stop STO, a fourth lens E4, a fifth lens E5, a sixth lens E6, a filter IR, a protective glass CG, and an image plane IMA.

[0047] The object plane side S1 of the first lens E1 is convex, and the image plane side S2 is concave.

[0048] The object plane side S3 of the second lens E2 is convex, and the image plane side S4 is concave.

[0049] The object plane side S5 of the third lens E3 is convex, and the image plane side S6 is convex.

[0050] The fourth lens E4 has a convex surface on its object side S8 and a convex surface on its image side S9;

[0051] The object plane side S9 of the fifth lens E5 is concave, and the image plane side S10 is convex.

[0052] The object plane side S11 of the sixth lens E6 is convex, and the image plane side S12 is convex.

[0053] The fourth lens E4 and the fifth lens E5 form a set of cemented lenses;

[0054] And it satisfies the following relationship:

[0055] 4.6<|f1 / f|<5.1; 2.5<|f2 / f|<3.1; 3.4<|f3 / f|<3.9; 11 .5<|f4 / f|<12.1; 33.1<|f5 / f|<33.7; 3.4<|f6 / f|<3.9;

[0056] Where f1 is the focal length of the first lens E1, f2 is the focal length of the second lens E2, f3 is the focal length of the third lens E3, f4 is the focal length of the fourth lens E4, f5 is the focal length of the fifth lens E5, f6 is the focal length of the sixth lens E6, and f is the effective focal length of the entire optical system.

[0057] As an improvement, the Abbe constant Vd2 of the second lens E2, the Abbe constant Vd4 of the fourth lens E4, and the Abbe constant Vd6 of the sixth lens E6 are all greater than 51 and less than 59.

[0058] As an improvement, the maximum field of view (FOV) of the optical system satisfies the following condition:

[0059] FOV ≥ 210°.

[0060] As an improvement, the maximum holoimage height of the optical system satisfies the following condition:

[0061] IHmax≥5.78mm.

[0062] As an improvement, the effective focal length f of the optical system satisfies the following condition:

[0063] 1.3mm≤f≤1.45mm.

[0064] As an improvement, the first lens E1 is meniscus-shaped and has a negative optical power;

[0065] The second lens E2 is concave-convex, with the object side S3 being convex and the image side S4 being concave, and its optical power is negative.

[0066] The third lens E3 is biconvex, with the object side S5 being a convex surface with a platform and the image side S6 being a convex surface, and its optical power is positive.

[0067] The fourth lens E4 is biconvex, with the object side S8 being convex and the image side S9 being a convex surface with a plateau. Its optical power is negative.

[0068] The fifth lens E5 is concave-convex, with the object plane side S9 being concave and the image plane side S10 being convex, and its optical power is positive.

[0069] The sixth lens E6 is biconvex, with the object side S11 being a small convex surface and the image side S12 being a large convex surface, and its optical power is positive.

[0070] As an improvement, the aperture ST0 is positioned between the third lens E3 and the fourth lens E4.

[0071] In this patent embodiment, when the working distance is infinity, the total focal length of the optical system (optical lens) is f=1.36mm, FNO=2.05, the maximum field of view FOV=210°, and the maximum holographic height is 5.78mm.

[0072] This specific embodiment is merely an explanation of the present utility model and is not intended to limit the present utility model. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present utility model, they are protected by patent law.

[0073] The parameters of each lens in this embodiment are listed in Table 1 below, and the aspherical coefficients of the lenses are shown in Table 2 below.

[0074] Table 1 Physical parameters of each lens

[0075]

[0076] Table 2 Aspherical coefficients of lenses

[0077]

[0078]

[0079] The aspherical coefficients satisfy the following equation:

[0080]

[0081] Where z is the aspherical sagitta, c is the paraxial curvature of the aspherical surface, the curvature is the reciprocal of the radius of curvature, y is the lens aperture, k is the conic coefficient, a4 is the 4th order aspherical coefficient, a6 is the 6th order aspherical coefficient, a8 is the 8th order aspherical coefficient, and a10 is the 10th order aspherical coefficient.

[0082] Specifically, in this embodiment, the R-value (radius of curvature), thickness, refractive index, Abbe number (ABB), and focal length (EFL-E) of each lens surface are shown in Table 1, and the aspherical parameters are shown in Table 2. In Table 1, Surf represents the mirror surface number, and INFINITY represents infinity. In Table 2, R1 represents the radius of curvature of the corresponding lens surface facing the object side, and R2 represents the radius of curvature of the corresponding lens surface facing the image side. A positive radius of curvature indicates that the mirror is curved towards the object side, and a negative radius of curvature indicates that the mirror is curved towards the image side. Mirror numbers 1 and 2 represent the two mirrors of the first lens E1 along the direction of light incidence, respectively; mirror numbers 3 and 4 represent the two mirrors of the second lens E2 along the direction of light incidence, respectively; mirror numbers 5 and 6 represent the two mirrors of the third lens E3 along the direction of light incidence, respectively; mirror number 8 represents the object-side mirror of the fourth lens E4; mirror number 10 represents the image-side mirror of the fifth lens E5; mirror number 9 represents the cemented surface of the fourth lens E4 and the fifth lens E5; and mirror numbers 11 and 12 represent the two mirrors of the sixth lens E6 along the direction of light incidence, respectively.

[0083] In this embodiment of the utility model, Figure 2 The modulation transfer function (MTF) curve, representing the visible light band, indicates the overall resolving power of an optical system. The horizontal axis represents spatial frequency, with units of period / mm (100 lp / mm), and the vertical axis represents the MTF value. The MTF value is used to evaluate the image quality of a lens, ranging from 0 to 1. It is worth noting that the optical transfer function is a relatively accurate, intuitive, and common way to evaluate the image quality of an optical system; the higher and smoother the curve, the better the image quality and the stronger the ability to reproduce the true image. Figure 2 It can be seen that in the visible light band, at a spatial frequency of 100 lp / mm, the MTF of the imaging region near the center is >0.7, indicating good imaging quality. Figure 3 This is represented as a defocus curve at 20°C in the visible light band. Figure 3 It can be seen that the lens has good MTF concentration, making focusing easy, and the defocus curve trend is consistent across different field of view angles. From Figure 4 and Figure 5 It can be seen that the defocus curves at low temperatures of -40℃ and high temperatures of 85℃ both meet the requirements of high resolution, with small changes in focus and stable thermal drift effect. Figure 6 Represented as a field curve diagram, by Figure 6 It can be seen that the field curvature value should be controlled between -0.04mm and 0.04mm. The smaller the field curvature value, the better the image quality of the lens. Figure 7The standard dot plot of this lens shows that its maximum holographic height is 5.78mm and its maximum field of view is 210 degrees. Figure 7 The 0.65 in the upper right corner corresponds to an incident light wavelength of 650nm, 0.61 corresponds to an incident light wavelength of 610nm, and so on.

Claims

1. A thermally stable large-target-area AVM optical imaging system, characterized in that: Along the optical axis from the object plane to the image plane, the components are as follows: first lens, second lens, third lens, aperture stop, fourth lens, fifth lens, sixth lens, filter, protective glass, and image plane. The first lens has a convex surface on the object side and a concave surface on the image side; The second lens has a convex surface on the object side and a concave surface on the image side; The third lens has a convex surface on both the object plane and the image plane sides; The fourth lens has a convex surface on both the object plane and the image plane sides; The fifth lens has a concave surface on the object plane side and a convex surface on the image plane side; The object plane side of the sixth lens is convex, and the image plane side is also convex. The fourth and fifth lenses form a set of cemented lenses; And it satisfies the following relationship: 4.6<|f1 / f|<5.1; 2.5<|f2 / f|<3.1; 3.4<|f3 / f|<3.9; 11 .5<|f4 / f|<12.1; 33.1<|f5 / f|<33.7; 3.4<|f6 / f|<3.9; Where f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, f6 is the focal length of the sixth lens, and f is the effective focal length of the entire optical system.

2. The thermally stable large-target-area AVM optical imaging system according to claim 1, characterized in that: The Abbe constants Vd2 of the second lens, Vd4 of the fourth lens, and Vd6 of the sixth lens are all greater than 51 and less than 59.

3. The thermally stable large-target-area AVM optical imaging system according to claim 1, characterized in that: The maximum field of view (FOV) of the optical system satisfies the following condition: FOV ≥ 210°.

4. The thermally stable large-target-area AVM optical imaging system according to claim 1, characterized in that: The maximum holoimage height of the optical system satisfies the following condition: IHmax≥5.78mm.

5. The thermally stable large-target-area AVM optical imaging system according to claim 1, characterized in that: The effective focal length f of the optical system satisfies the following condition: 1.3mm≤f≤1.45mm.

6. The thermally stable large-target-area AVM optical imaging system according to claim 1, characterized in that: The first lens is meniscus-shaped and has a negative optical power. The second lens is concave-convex, with the object side being convex and the image side being concave, and its optical power is negative. The third lens is biconvex, with a convex surface on the object side and a convex surface on the image side, and its optical power is positive. The fourth lens is biconvex, with a convex surface on the object side and a convex surface with a plateau on the image side, and its optical power is negative. The fifth lens is concave-convex, with the object side being concave and the image side being convex, and its optical power is positive. The sixth lens is biconvex, with both the object and image sides being convex, and its optical power is positive.

7. The thermally stable large-target-area AVM optical imaging system according to claim 1, characterized in that: The aperture stop is positioned between the third lens and the fourth lens.

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