Day and night confocal large chief ray angle in-vehicle monitoring optical system

Abstract

The application discloses a day and night confocal large chief ray angle in-vehicle monitoring optical system and relates to the technical field of optical imaging. The technical scheme points of the application are as follows: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, a filter, a protective glass and an image plane are arranged along the direction from the object side to the image side; the first lens is a meniscus lens with negative optical power; the second lens is a meniscus lens with negative optical power; the third lens is a meniscus lens with positive optical power; the fourth lens is a double convex lens with positive optical power; the fifth lens is a concave-convex lens with negative optical power; the sixth lens is a double convex lens with positive optical power; and the seventh lens is an M-shaped lens with negative optical power. The optical system has the characteristics of small size, large field angle, 5M high-definition application, day and night confocal, purple edge optimization, thermal drift stability and large CRA angle.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and in particular to an in-cabin passenger monitoring optical system that combines day and night confocality, infrared confocality, large principal ray incident angle, and strong thermal drift stability. Background Technology

[0002] Currently, automotive electronics are gradually becoming standard equipment in modern cars, and rearview camera systems are no longer sufficient to meet market demands. With the continuous segmentation of professional functions and application areas, different applications have emerged, such as side-view, surround-view, electronic rearview, and cabin monitoring. OMS, or Occupant Monitoring System, tracks the driver's status, including alerts for driver fatigue, and can even track rear-seat passengers to ensure the safety of both driver and passengers. Examples include using cameras to detect whether passengers are wearing seat belts correctly, alerting them to inattention due to fatigue, and detecting children left in the car.

[0003] Existing automotive OMS lens imaging technologies generally suffer from problems such as complex structure, long overall lens length, small field of view, low resolution, significant changes in lens clarity under different day and night conditions, unstable thermal drift during high and low temperature operation, and inability to meet the requirements of CRA ultra-large angle configuration chips. Summary of the Invention

[0004] This invention provides an in-vehicle monitoring optical system and camera device with day and night confocal large main beam angle, which combines the characteristics of small size, large field of view, 5M high-definition application, day and night confocal, purple fringing optimization and thermal drift stability, and large CRA angle.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a day and night confocal large principal beam angle in-vehicle monitoring optical system, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, a filter, a protective glass, and an image plane arranged along the direction from the object side to the image side;

[0006] The first lens is a meniscus lens with negative optical power, the second lens is a meniscus lens with negative optical power, the third lens is a meniscus lens with positive optical power, the fourth lens is a biconvex lens with positive optical power, the fifth lens is a concave-convex lens with negative optical power, the sixth lens is a biconvex lens with positive optical power, and the seventh lens is an M-type lens with negative optical power.

[0007] The ratio of the focal length of the first to the seventh lens to the focal length of the lens satisfies the following set relationship: 4.2 < |f1 / f| < 5.1, 1.5 < |f2 / f| < 2.4, 3.9 < |f3 / f| < 4.6, 1.3 < |f4 / f| < 2.3, 4.0 < |f5 / f| < 4.7, 1.5 < |f6 / f| < 2.2, 3.6 < |f7 / f| < 4.3;

[0008] Where f1 represents the effective focal length of the first lens, f2 represents the effective focal length of the second lens, f3 represents the effective focal length of the third lens, f4 represents the effective focal length of the fourth lens, f5 represents the effective focal length of the fifth lens, f6 represents the effective focal length of the sixth lens, f7 represents the effective focal length of the seventh lens, and f represents the effective focal length of the optical system.

[0009] In some embodiments, the first and fourth lenses are spherical glass lenses, and the remaining lenses are plastic lenses.

[0010] In some embodiments, the lens material used has low dispersion properties.

[0011] In some embodiments, the filter has a confocal function for visible light and infrared light in the infrared 940nm band.

[0012] In some embodiments, the refractive index of both the second lens and the sixth lens is 1.54, and the Abbe number is greater than 52 and less than 60.

[0013] The refractive index of the third, fifth, and seventh lenses is 1.66, and the Abbe coefficients are all greater than 16 and less than 25.

[0014] In some embodiments, the first lens has a convex surface facing the object side and a concave surface facing the image side; the second lens has a convex surface facing the object side and a concave surface facing the image side; the third lens has a convex surface facing the object side and a slightly concave surface facing the image side; the fourth lens has a slightly convex surface facing the object side and a large convex surface facing the image side; the fifth lens has a slightly convex surface facing the object side and a concave surface facing the image side; the sixth lens has a slightly convex surface facing the object side and a large convex surface facing the image side; and the seventh lens has a large concave surface facing the object side and an M-shaped surface facing the image side.

[0015] In some embodiments, the optical system satisfies the following condition: TTL / h < 2.05;

[0016] Where TTL represents the total length of the optical system, and h represents the size of the image plane.

[0017] In some embodiments, the total length TTL of the optical system satisfies the following condition: 11.5mm ≤ TTL ≤ 14mm.

[0018] In some embodiments, the relative aperture of the optical system is F2.0.

[0019] In some embodiments, the optical system has the following parameter values:

[0020] The focal length is 1.7mm;

[0021] The hologram height is 6.45 mm;

[0022] TTL is 13mm;

[0023] The field of view is 179°;

[0024] The CRA principal ray incident angle of the optical system is 29°.

[0025] In summary, the present invention has the following beneficial effects:

[0026] This day-and-night confocal, large-prime-angle in-vehicle monitoring optical system uses spherical glass lenses for the first and fourth lenses, while the remaining lenses are made of plastic. This reduces costs while effectively minimizing spherical aberration, coma, astigmatism, field curvature, positional chromatic aberration, and magnification chromatic aberration by employing an optical system composed of lenses with specific structural shapes and a reasonable power distribution. This improves the product's resolution and chromatic aberration correction, meeting the requirements of 5M high-definition applications. The design utilizes low-dispersion lens materials, optimizing the purple fringing effect at object edges for better image reproduction. Simultaneously, the entire optical system has thermal compensation, maintaining thermal drift stability at high temperatures (85°C) and low temperatures (-40°C), thus solving the problem of excessive temperature drift and ensuring consistent resolution under varying environmental conditions. With an aperture of F2.0, it absorbs more light and incorporates an infrared 940° confocal function, enabling better monitoring of passenger behavior in low-light environments and preventing driver fatigue. With a focal length of 1.7mm, a full-image height of 6.45mm, a TTL of 13mm, and a field of view of 179°, this optical system achieves an ultra-short, large target surface structure, allowing for a wider shooting range and a more compact overall size, making it easy to install in vehicles. It can be matched with 1 / 2.8” target surface chips. The CRA principal ray incident angle of this optical system is 29 degrees, which can be matched with chips with a large CRA angle without causing color cast due to excessive differences in the CRA angle of the matched chips. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a lens according to an embodiment of the present invention;

[0028] Figure 2This is an analytical diagram of 100 lp / mm MTF (Modulation Transfer Function) at 20°C according to an embodiment of the present invention;

[0029] Figure 3 This is a defocusing curve at 20°C with a speed of 100 lp / mm, according to an embodiment of the present invention.

[0030] Figure 4 This is a defocusing curve at 85°C and 100 lp / mm, according to an embodiment of the present invention.

[0031] Figure 5 This is a defocusing curve at -40℃ with 100 lp / mm according to an embodiment of the present invention;

[0032] Figure 6 This is a field curvature diagram of an embodiment of the present invention;

[0033] Figure 7 This is a diagram of the CRA (Chief Ray Angle) incident angle in an embodiment of the present invention.

[0034] In the diagram: E1: First lens; E2: Second lens; E3: Third lens; STO (Stop): Aperture stop; E4: Fourth lens; E5: Fifth lens; E6: Sixth lens; E7: Seventh lens; IR (Infrared Filter): Filter; CG (Cover Glass): Protective glass; IMA (Image Surface): Image plane;

[0035] S1: The object-side side of the first lens; S2: The image-side side of the first lens; S3: The object-side side of the second lens; S4: The image-side side of the second lens; S5: The object-side side of the third lens; S6: The image-side side of the third lens; S8: The object-side side of the fourth lens; S9: The image-side side of the fourth lens; S10: The object-side side of the fifth lens; S11: The image-side side of the fifth lens; S12: The object-side side of the sixth lens; S13: The image-side side of the sixth lens; S14: The object-side side of the seventh lens; S15: The image-side side of the seventh lens. Detailed Implementation

[0036] Embodiments of the present invention are described in detail below, examples of which are illustrated 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 the present invention, and should not be construed as limiting the present invention.

[0037] In the description of this invention, 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 invention 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 invention.

[0038] 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 invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0039] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," 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 invention according to the specific circumstances.

[0040] In this embodiment, the parameters of the lens group are listed in Table 1:

[0041]

[0042] Table 1

[0043] Aspherical coefficients are shown in Table 2:

[0044]

[0045] Table 2

[0046] The aspherical coefficients satisfy the following equation:

[0047]

[0048] in, For aspherical sag, For aspherical paraxial curvature, For lens diameter, The conic coefficient, The coefficients of the fourth order asphericity, The aspheric coefficient of the 6th order. The aspheric coefficient of the 8th order is For the 10th order aspheric coefficient, It is the 12th order aspheric coefficient.

[0049] Specifically, the R-values ​​and thicknesses of each lens surface in this embodiment are shown in Table 1, and the aspherical parameters are shown in Table 2.

[0050] The optical system provided in Table 1 has an effective focal length of 1.7mm, a full-image height of 6.45mm, a light-transmitting aperture of F2.0, a TTL of 13mm, a field of view of 179°, and a CRA principal ray incident angle of 29 degrees. In Table 1, mirror numbers 1 and 2 represent the two mirrors of lens 1 along the direction of light incidence, mirror numbers 3 and 4 represent the two mirrors of lens 2 along the direction of light incidence, mirror numbers 5 and 6 represent the two mirrors of lens 3 along the direction of light incidence, mirror numbers 8 and 9 represent the two mirrors of lens 4 along the direction of light incidence, mirror numbers 10 and 11 represent the two mirrors of lens 5 along the direction of light incidence, mirror numbers 12 and 13 represent the two mirrors of lens 6 along the direction of light incidence, mirror numbers 14 and 15 represent the two mirrors of lens 7 along the direction of light incidence, mirror numbers 16 and 17 represent the two mirrors of the filter along the direction of light incidence, mirror numbers 18 and 19 represent the two mirrors of the protective glass along the direction of light incidence, and IMA represents the imaging surface.

[0051] like Figure 1 As shown, in this embodiment of the invention, the first lens is a meniscus lens with negative optical power, the second lens is a meniscus lens with negative optical power, the third lens is a meniscus lens with positive optical power, the fourth lens is a biconvex lens with positive optical power, the fifth lens is a concave-convex lens with negative optical power, the sixth lens is a biconvex lens with positive optical power, and the seventh lens is an M-type lens with negative optical power.

[0052] The ratio of the focal length of the first to seventh lenses to the focal length of the lens satisfies the following set relationship: 4.2 < |f1 / f| < 5.1, 1.5 < |f2 / f| < 2.4, 3.9 < |f3 / f| < 4.6, 1.3 < |f4 / f| < 2.3, 4.0 < |f5 / f| < 4.7, 1.5 < |f6 / f| < 2.2, 3.6 < |f7 / f| < 4.3;

[0053] Where f1 represents the effective focal length of the first lens, f2 represents the effective focal length of the second lens, f3 represents the effective focal length of the third lens, f4 represents the effective focal length of the fourth lens, f5 represents the effective focal length of the fifth lens, f6 represents the effective focal length of the sixth lens, f7 represents the effective focal length of the seventh lens, and f represents the effective focal length of the optical system.

[0054] In some embodiments, the first and fourth lenses are spherical glass lenses, and the remaining lenses are plastic lenses.

[0055] In some embodiments, the lens material used has low dispersion properties.

[0056] In some embodiments, the filter has a confocal function for visible light and infrared light in the infrared 940nm band.

[0057] In some embodiments, the refractive index of both the second lens and the sixth lens is 1.54, and the Abbe number is greater than 52 and less than 60.

[0058] The refractive index of the third, fifth, and seventh lenses is 1.66, and the Abbe coefficients are all greater than 16 and less than 25.

[0059] In some embodiments, the first lens has a convex surface facing the object side and a concave surface facing the image side; the second lens has a convex surface facing the object side and a concave surface facing the image side; the third lens has a convex surface facing the object side and a slightly concave surface facing the image side; the fourth lens has a slightly convex surface facing the object side and a large convex surface facing the image side; the fifth lens has a slightly convex surface facing the object side and a concave surface facing the image side; the sixth lens has a slightly convex surface facing the object side and a large convex surface facing the image side; and the seventh lens has a large concave surface facing the object side and an M-shaped surface facing the image side.

[0060] In some embodiments, the optical system satisfies the following condition: TTL / h < 2.05;

[0061] Where TTL represents the total length of the optical system, and h represents the size of the image plane.

[0062] In some embodiments, the total length TTL of the optical system satisfies the following condition: 11.5mm ≤ TTL ≤ 14mm.

[0063] In some embodiments, the relative aperture of the optical system is F2.0.

[0064] In some embodiments, the optical system has the following parameter values:

[0065] The focal length is 1.7mm;

[0066] The hologram height is 6.45 mm;

[0067] TTL is 13mm;

[0068] The field of view is 179°;

[0069] The CRA principal ray incident angle of the optical system is 29°.

[0070] Figure 2 This is a modulation transfer function (MTF) curve for the visible light band, representing the overall resolving power of an optical system. The horizontal axis represents spatial frequency, in cycles per millimeter (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 in the imaging region near the center is >0.6, indicating good image quality. This demonstrates that the optical system possesses high resolution across the entire field of view, meeting the requirements of 5M high-definition applications. Figure 3 The defocus curve shows that the lens has good MTF concentration, facilitating focusing. It also indicates that the optical system has a large defocus amount across the entire field of view, demonstrating good day and night confocal performance. From... Figure 4 and Figure 5 It can be seen that the defocus curves at both high and low temperatures meet the requirements of high resolution, the focal point change of the defocus curve is small, and the thermal drift effect is stable. The optical system has a small defocus change in the entire field of view, indicating that the optical system has good thermal drift stability. Figure 6 Representing the field curve diagram, by Figure 6 It can be seen that the field curvature value is controlled between -0.05mm and 0.05mm. The smaller the field curvature value, the better the image quality of the lens. It can be seen that the optical system has a small field curvature value in the entire field of view, indicating that the optical system has good imaging plane performance. Figure 7 This represents the CRA principal ray incidence angle diagram, from Figure 7 It is known that the incident angle of the CRA principal ray is 29 degrees, which can be matched with chips with a larger CRA angle, and will not cause color distortion due to excessive difference in the CRA angle of the matching chip.

[0071] In summary, this invention uses a structure of 2 glass elements and 5 plastic aspherical elements, resulting in low mass production costs. At the same time, it employs an optical system composed of lenses with specific structural shapes and reasonable optical power distribution to optimize aberrations and effectively improve product resolution, meeting the requirements of 5M high-definition applications. Under the same conditions, an 8-glass structure is difficult to achieve 5M high-definition.

[0072] This invention employs low-dispersion lens material to optimize the purple fringing effect at the edges of objects, better restoring the true scene. At the same time, it enables the entire optical system to have a thermal compensation effect, stabilizing thermal drift at high temperatures of 85 degrees Celsius and low temperatures of -40 degrees Celsius, solving the problem of excessive temperature drift at high and low temperatures, and ensuring use in extreme external environments.

[0073] This invention features a focal length of 1.7mm, a full-image height of 6.45mm, and a TTL of 13mm, achieving an ultra-short, large target surface structure. This results in a more compact overall size, facilitating installation in vehicles. It is matched with a 1 / 2.8” target surface chip, providing a field of view of 179° for a wider shooting range. The aperture reaches F2.0, and it is designed with built-in infrared 940 confocal focus to meet the requirements of low-light conditions at night, preventing fatigue driving at night.

[0074] The CRA main ray incident angle of this invention is 29 degrees, which can be matched with chips with a larger CRA angle, and will not cause color distortion due to excessive difference in CRA angle between the matching chips.

[0075] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A day / night confocal large principal beam angle in-vehicle monitoring optical system, characterized in that: It includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, a filter, a protective glass, and an image plane arranged along the direction from the object side to the image side; The optical system has 7 lenses; The first lens is a meniscus lens with negative optical power, the second lens is a meniscus lens with negative optical power, the third lens is a meniscus lens with positive optical power, the fourth lens is a biconvex lens with positive optical power, the fifth lens is a concave-convex lens with negative optical power, the sixth lens is a biconvex lens with positive optical power, and the seventh lens is an M-type lens with negative optical power. The ratio of the focal length of the first to seventh lenses to the focal length of the optical system satisfies the following set relationship: 4.2 < |f1 / f| < 5.1, 1.5 < |f2 / f| < 2.4, 3.9 < |f3 / f| < 4.6, 1.3 < |f4 / f| < 2.3, 4.0 < |f5 / f| < 4.7, 1.5 < |f6 / f| < 2.2, 3.6 < |f7 / f| < 4.3; Where f1 represents the effective focal length of the first lens, f2 represents the effective focal length of the second lens, f3 represents the effective focal length of the third lens, f4 represents the effective focal length of the fourth lens, f5 represents the effective focal length of the fifth lens, f6 represents the effective focal length of the sixth lens, f7 represents the effective focal length of the seventh lens, and f represents the effective focal length of the optical system. The optical system satisfies the following condition: TTL / h < 2.05; Where TTL represents the total length of the optical system, and h represents the size of the image plane.

2. The in-vehicle monitoring optical system with a large principal beam angle and day / night confocal focus as described in claim 1, characterized in that: The first and fourth lenses are spherical glass lenses, while the remaining lenses are plastic lenses.

3. The in-vehicle monitoring optical system with a large principal beam angle and day / night confocal focus as described in claim 1, characterized in that: The filter has the function of confocal focusing of visible light and infrared light in the infrared 940nm band.

4. The in-vehicle monitoring optical system with a large principal beam angle and day / night confocal focus as described in claim 1, characterized in that: The refractive index of both the second and sixth lenses is 1.54, and the Abbe number is greater than 52 and less than 60. The refractive index of the third, fifth, and seventh lenses is 1.66, and the Abbe coefficients are all greater than 16 and less than 25.

5. The in-vehicle monitoring optical system with a large principal beam angle and day / night confocal focus as described in claim 1, characterized in that: The first lens has a convex surface facing the object side and a concave surface facing the image side; the second lens has a convex surface facing the object side and a concave surface facing the image side; the third lens has a convex surface facing the object side and a concave surface facing the image side; the fourth lens has a convex surface facing the object side and a convex surface facing the image side; the fifth lens has a convex surface facing the object side and a concave surface facing the image side; the sixth lens has a convex surface facing the object side and a convex surface facing the image side; and the seventh lens has a concave surface facing the object side and an M-shaped surface facing the image side.

6. The in-vehicle monitoring optical system with a large principal beam angle and day / night confocal focus as described in claim 1, characterized in that: The total length TTL of the optical system satisfies the following condition: 11.5mm≤TTL≤14mm.

7. The in-vehicle monitoring optical system with a large principal beam angle and day / night confocal focus as described in claim 6, characterized in that: The relative aperture of the optical system is F2.

0.

8. A day / night confocal large principal beam angle in-vehicle monitoring optical system according to claim 6 or 7, characterized in that: The optical system has the following parameter values: The focal length is 1.7mm; The hologram height is 6.45 mm; TTL is 13mm; The field of view is 179°; The CRA principal ray incident angle of the optical system is 29°.

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