Miniaturized OMS lens optical system with stable thermal drift

Abstract

The utility model discloses a miniaturized OMS lens optical system with stable thermal drift, and relates to the technical field of optical systems and vehicle-mounted imaging devices. The lens sequentially comprises a first meniscus lens, a second concave-convex lens, a third concave-convex lens, a fourth double-convex lens, a fifth concave-convex lens, a sixth double-convex lens, a seventh concave-convex lens, an optical filter, protective glass and an image plane from an object plane to the image plane along an optical axis, and a diaphragm is arranged between the fourth lens and the fifth lens; the first lens, the second lens, the third lens, the fifth lens and the seventh lens are lenses with negative focal lengths, the fourth lens and the sixth lens are lenses with positive focal lengths, and the fifth lens and the sixth lens are combined to form a balsaming lens. The defects that an existing vehicle-mounted OMS lens is too large in size and difficult to adapt to high and low temperature changing environments are effectively overcome through the lens surface type design and the mode of matching the positive lens and the negative lens, and the vehicle-mounted OMS lens has the advantages of being small in size, infrared confocal, wide in angle, large in target surface, stable in thermal drift and the like.

Description

Technical Field

[0001] The utility model relates to the technical field of optical systems and vehicle-mounted imaging devices, in particular to a miniaturized thermal drift-stabilized OMS lens optical system. Background Art

[0002] At present, automobile electronics has gradually become a standard configuration of modern cars. The rear reversing visualization system can no longer meet the needs of the market. Now, with the continuous subdivision of professional functions and application fields, different application aspects such as side view, surround view, electronic rear view and in-cabin monitoring have emerged. OMS, or in-cabin occupant monitoring system, tracks the status of the car driver, including some reminders of driving fatigue, and can even track the rear passengers to ensure the safety of the driver and passengers. For example, use a camera to detect whether the passenger wears the seat belt correctly, remind when the attention is distracted when tired, and detect children left in the car. However, in the existing vehicle-mounted OMS lens imaging technology, there are generally problems such as complex structure, long total lens length, small field of view, small target surface, large lens clarity changes in different environments during the day and night, and unstable thermal drift during high and low temperature operation. In response to such problems, the present utility model embodiment studies and designs a miniaturized thermal drift-stabilized OMS lens optical system, which takes into account the characteristics of small size, large field of view, large target surface, day and night confocal, and thermal drift stability. Utility Model Content

[0003] The utility model proposes a miniaturized thermal drift-stabilized OMS lens optical system. The miniaturized thermal drift-stabilized OMS lens optical system has the characteristics of miniaturization, wide angle, large target surface, day and night infrared confocality, and good temperature resistance.

[0004] The above technical objectives of the utility model are achieved through the following technical solutions: a miniaturized thermal drift stabilized OMS lens optical system, which includes, in sequence from the object plane to the image plane along the optical axis: a first lens, a second lens, a third lens, a fourth lens, an aperture, a fifth lens, a sixth lens, a seventh lens, a filter, a protective glass and an image plane;

[0005] The first lens is a meniscus lens with negative optical power;

[0006] The second lens is a meniscus lens with negative optical power;

[0007] The third lens is a meniscus lens with negative optical power;

[0008] The fourth lens is a biconvex lens with positive optical power;

[0009] The fifth lens is a meniscus lens with negative optical power;

[0010] The sixth lens is a biconvex lens with positive optical power;

[0011] The seventh lens is an M-type lens with negative optical power;

[0012] The fifth lens and the sixth lens form a cemented lens group;

[0013] And the following relationship is satisfied:

[0014] 1.42<|f1 / f|<1.65, 7.9<|f2 / f|<9.3, 28.5<|f3 / f|<29.8, 1<| f4 / f|<2.2, 9.8<|f5 / f|<11, 2.1<|f6 / f|<3.2, 4<|f7 / f|<5.3;

[0015] Among them, f1 represents the effective focal length of the first meniscus lens, f2 represents the effective focal length of the second concave-convex lens, f3 represents the effective focal length of the third concave-convex lens, f4 represents the effective focal length of the fourth biconvex lens, f5 represents the effective focal length of the fifth concave-convex lens, f6 represents the effective focal length of the sixth biconvex lens, f7 represents the effective focal length of the seventh M-type lens, and f represents the effective focal length of the optical system.

[0016] In some embodiments, the field of view FOV of the optical system satisfies the following conditions:

[0017] 153°≤FOV≤159°.

[0018] In some embodiments, the total optical length TTL of the optical system satisfies the following conditions:

[0019] 13.5mm≤TTL≤14.5mm.

[0020] In some embodiments, the maximum total image height of the optical system satisfies the following conditions:

[0021] IH≥7.4.

[0022] In some embodiments, the optical system satisfies the following conditional formula:

[0023] 0.25<(h / 2) / (f×tan(FOV / 2))<0.37.

[0024] Wherein: f represents the effective focal length of the optical system, FOV represents the maximum field of view of the optical system, and h represents the maximum image circle of the optical system.

[0025] In some embodiments, a surface of the first lens facing the object side is convex, and a surface of the first lens facing the image side is concave;

[0026] The second lens has a concave surface facing the object side and a convex surface facing the image side;

[0027] The third lens has a concave surface facing the object side and a convex surface facing the image side.

[0028] The fourth lens has a convex surface facing the object side and a convex surface facing the image side;

[0029] The fifth lens has a convex surface facing the object side and a concave surface facing the image side.

[0030] The sixth lens has a convex surface facing the object side and a convex surface facing the image side;

[0031] The seventh lens is an M-type lens, with a small convex surface on the object side and a small concave surface on the image side.

[0032] In summary, the utility model has the following beneficial effects:

[0033] Miniaturization: The total length of the optical system is 14mm, and the minimum front diameter is 9mm, which perfectly meets the needs of miniaturization in the OMS cabin.

[0034] Wide-angle field of view 153°≤FOV≤159°: It is compatible with driver fatigue driving monitoring and rear passenger monitoring, with a larger shooting range. It covers the traditional DMS (driver monitoring system) lens application and the rear-seat monitoring application in the car to ensure the personal safety of passengers in the car.

[0035] Large target surface: The full image height is 7.41mm, which can match 1 / 2.4” large target surface chips, meeting the market demand for matching large target surface chips.

[0036] Day and night infrared confocal: It can take into account both 400-700nm visible light and 940nm near-infrared light, with good infrared MTF data, achieving the technical standards of high-definition monitoring during the day and at night.

[0037] Good temperature resistance: The entire optical system has a thermal compensation effect, and the operating temperature is -40℃ to 85℃, which well ensures that the product's resolution remains unchanged in complex temperature scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the lens of the utility model;

[0039] Figure 2 This is the 100lp / mm MTF analysis diagram of the utility model at 20°C;

[0040] Figure 3 This is the defocus curve of 100lp / mm at 20°C of the utility model;

[0041] Figure 4This is the 100lp / mm defocus curve of the utility model at -40°C;

[0042] Figure 5 This is the defocus curve of 100lp / mm at 85°C of the utility model;

[0043] Figure 6 This is the MTF analysis diagram of the utility model under visible light conditions;

[0044] Figure 7 This is the MTF analysis diagram of the utility model under infrared light conditions.

[0045] In the figure: E1: first lens; E2: second lens; E3: third lens; E4: fourth lens; STO (Stop): aperture; E5: fifth lens; E6: sixth lens; E7: seventh lens; IR (Infrared Filter): filter; CG (Coverglass): protective glass; IMA (Image Surface): image surface;

[0046] S1: the side of the first lens facing the object side; S2: the side of the first lens facing the image side; S3: the side of the second lens facing the object side; S4: the side of the second lens facing the image side; S5: the side of the third lens facing the object side; S6: the side of the third lens facing the image side; S7: the side of the fourth lens facing the object side; S8: the side of the fourth lens facing the image side; S10: the side of the fifth lens facing the object side; S11: the side where the fifth lens and the sixth lens are bonded to each other; S12: the side of the sixth lens facing the image side; S13: the side of the seventh M-type lens with the convex surface facing the object side; S14: the side of the seventh M-type lens with the concave surface facing the image side. DETAILED DESCRIPTION

[0047] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0048] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and 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, and therefore cannot be understood as a limitation on the present invention.

[0049] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0050] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] like Figure 1 As shown, this embodiment provides a miniaturized thermal drift stabilized OMS lens optical system, which includes, along the optical axis from the object plane to the image plane, a first lens, a second lens, a third lens, a fourth lens, an aperture, a fifth lens, a sixth lens, a seventh lens, a filter, a protective glass and an image plane;

[0052] The first lens is a meniscus lens with negative optical power;

[0053] The second lens is a meniscus lens with negative optical power;

[0054] The third lens is a meniscus lens with negative optical power;

[0055] The fourth lens is a biconvex lens with positive optical power;

[0056] The fifth lens is a meniscus lens with negative optical power;

[0057] The sixth lens is a biconvex lens with positive optical power;

[0058] The seventh lens is an M-type lens with negative optical power;

[0059] The fifth lens and the sixth lens form a cemented lens group;

[0060] And the following relationship is satisfied:

[0061] 1.42<|f1 / f|<1.65, 7.9<|f2 / f|<9.3, 28.5<|f3 / f|<29.8, 1<| f4 / f|<2.2, 9.8<|f5 / f|<11, 2.1<|f6 / f|<3.2, 4<|f7 / f|<5.3;

[0062] Among them, f1 represents the effective focal length of the first meniscus lens, f2 represents the effective focal length of the second concave-convex lens, f3 represents the effective focal length of the third concave-convex lens, f4 represents the effective focal length of the fourth biconvex lens, f5 represents the effective focal length of the fifth concave-convex lens, f6 represents the effective focal length of the sixth biconvex lens, f7 represents the effective focal length of the seventh M-type lens, and f represents the effective focal length of the optical system.

[0063] As an improvement, the field of view FOV of the optical system satisfies the following conditions:

[0064] 153°≤FOV≤159°.

[0065] As an improvement, the total optical length TTL of the optical system meets the following conditions:

[0066] 13.5mm≤TTL≤14.5mm.

[0067] As an improvement, the maximum full image height of the optical system satisfies the following conditions:

[0068] IH≥7.4.

[0069] As an improvement, the optical system satisfies the following conditional formula:

[0070] 0.25<(h / 2) / (f×tan(FOV / 2))<0.37.

[0071] Wherein: f represents the effective focal length of the optical system, FOV represents the maximum field of view of the optical system, and h represents the maximum image circle of the optical system.

[0072] As an improvement, the first lens has a convex surface facing the object side and a concave surface facing the image side;

[0073] The second lens has a concave surface facing the object side and a convex surface facing the image side;

[0074] The third lens has a concave surface facing the object side and a convex surface facing the image side.

[0075] The fourth lens has a convex surface facing the object side and a convex surface facing the image side;

[0076] The fifth lens has a convex surface facing the object side and a concave surface facing the image side.

[0077] The sixth lens has a convex surface facing the object side and a convex surface facing the image side;

[0078] The seventh lens is an M-type lens, with a small convex surface on the object side and a small concave surface on the image side.

[0079] In the embodiment of this patent, when the working distance is infinity, the total focal length of the lens is f=2.61mm, the field of view FOV=156°, the total optical length TTL is 14mm, and the maximum image circle is 7.41mm.

[0080] The parameters of the lens group are listed in Table 1:

[0081]

[0082] Table 1

[0083] Aspheric coefficients are shown in Table 2:

[0084]

[0085]

[0086]

[0087] Table 2

[0088] The aspheric coefficients satisfy the following equation:

[0089]

[0090] Among them, z is the aspheric surface sag, c is the aspheric surface paraxial curvature, y is the lens aperture, k is the cone coefficient, a4 is the 4th aspheric surface coefficient, a6 is the 6th aspheric surface coefficient, a8 is the 8th aspheric surface coefficient, a 10 is the 10th-order aspheric coefficient, a 12 is the 12th-order aspheric coefficient, a 14 is the 14th-order aspheric coefficient.

[0091] Specifically, the R value (Radius curvature radius), thickness (Thickness), refractive index (Index), and Abbe coefficient (ABB) of each lens surface in this embodiment are shown in Table 1, and the aspheric surface parameters are shown in Table 2.

[0092] In the embodiment of the present utility model, Figure 2 It is a modulation transfer function (MTF) curve at 100lp / mm in the visible light band at 20°C, which represents the comprehensive resolution capability of the optical system. The horizontal axis of the figure represents the spatial frequency, in cycles / mm, and the vertical axis represents the value of the modulation transfer function (MTF). The value of MTF is used to evaluate the imaging quality of the lens, and the range is 0-1. It is particularly pointed out that the optical transfer function is a relatively accurate, intuitive and common way to evaluate the imaging quality of an optical system. The higher and smoother the curve is, the better the imaging quality of the system is, and the stronger the ability to restore the real image is. Figure 2It can be seen that when the spatial frequency of the visible light band is 100lp / mm, the MTF of the imaging area near the center is > 0.6, and the imaging quality is good. Figure 3 It is represented as the defocus curve at 20℃ in the visible light band. Figure 3 It can be seen that the MTF concentration of this lens is good, which is convenient for focusing. Figure 4 and Figure 5 It can be seen that the defocus curves at low temperature of -40℃ and high temperature of 85℃ both meet the requirements of high resolution, the focus change of the defocus curve is small, and the temperature resistance is good; Figure 6 , Figure 7 It can be seen that under two different ambient light conditions, visible light and infrared light, the MTF attenuation is small, and the MTF in the central imaging area is > 0.6, which meets the requirements of day and night confocality.

[0093] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, 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 miniaturized thermal drift stabilized OMS lens optical system, characterized by: The optical axis includes, from the object plane to the image plane, a first lens, a second lens, a third lens, a fourth lens, an aperture, a fifth lens, a sixth lens, a seventh lens, a filter, a protective glass and an image plane; 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 negative optical power; The fourth lens is a biconvex lens with positive optical power; The fifth lens is a meniscus lens with negative optical power; The sixth lens is a biconvex lens with positive optical power; The seventh lens is an M-type lens with negative optical power; The fifth lens and the sixth lens form a cemented lens group; And the following relationship is satisfied: 1.42<|f1 / f|<1.65, 7.9<|f2 / f|<9.3, 28.5<|f3 / f|<29.8, 1<| f4 / f|<2.2, 9.8<|f5 / f|<11, 2.1<|f6 / f|<3.2, 4<|f7 / f|<5.3; Among them, 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.

2. A miniaturized thermal drift stabilized OMS lens optical system according to claim 1, characterized in that: The field of view FOV of the optical system meets the following conditions: 153°≤FOV≤159°.

3. The miniaturized thermal drift stabilized OMS lens optical system according to claim 1, characterized in that: The total optical length TTL of the optical system meets the following conditions: 13.5mm≤TTL≤14.5mm.

4. The miniaturized thermal drift stabilized OMS lens optical system according to claim 1, characterized in that: The maximum total image height of the optical system meets the following conditions: IH≥7.

4.

5. The miniaturized thermal drift stabilized OMS lens optical system according to claim 1, characterized in that: The optical system satisfies the following conditional formula: 0.25<(h / 2) / (f×tan(FOV / 2))<0.37; Wherein: f represents the effective focal length of the optical system, FOV represents the maximum field of view of the optical system, and h represents the maximum image circle of the optical system.

6. The miniaturized thermal drift stabilized OMS lens optical system according to 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 concave surface facing the object side and a convex surface facing the image side; The third lens has a concave surface facing the object side and a convex 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; The seventh lens is an M-type lens, with a small convex surface on the object side and a small concave surface on the image side.

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