A miniaturized large-aperture TOF optical system for in-cabin gesture recognition

Abstract

The present invention relates to a miniaturized, large-aperture time-of-flight (TOF) optical system for in-cabin gesture recognition, and relates to the field of optical imaging technology. Through a specific lens combination design, the system achieves an optical length of less than 10 mm, an aperture value of F1.2, and is optimized for infrared wavelengths of 940 nm. Suitable for scenarios such as in-vehicle gesture recognition, the system exhibits excellent imaging quality and thermal stability, capable of maintaining resolution in complex temperature environments. The advantages of the present invention lie in its miniaturized design, ease of installation, improved imaging quality due to its large aperture, and enhanced applicability and reliability due to its optimization for specific wavelengths. This system not only meets the needs of in-cabin gesture recognition but also provides a reliable optical solution for applications such as in-vehicle entertainment interaction.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging technology, and in particular to a miniaturized large-aperture in-cabin gesture recognition TOF (Time-of-Flight) optical system. Background Art

[0002] With the rapid development of intelligent recognition technology in recent years, time-of-flight (TOF) depth sensing has gained widespread application. This technology transmits light and measures the time or phase difference between emission and reflection to obtain depth information of the captured scene, enabling 3D modeling. However, existing TOF optical systems suffer from issues such as excessive size, insufficient optimization for specific wavelengths (such as infrared 940nm), and poor thermal stability, limiting their application in scenarios such as in-cabin gesture recognition. Summary of the Invention

[0003] The present invention provides a miniaturized large-aperture TOF optical system for in-cabin gesture recognition, aiming to solve the problems in the prior art.

[0004] The above technical objectives of the present invention are achieved through the following technical solutions: a miniaturized large-aperture in-cabin gesture recognition TOF optical system, comprising a first lens, a second lens, an aperture, a third lens, a fourth lens, a fifth lens, a filter, a protective glass, and an image plane arranged in a direction from the object side to the image side, wherein:

[0005] The first lens is a meniscus lens with negative optical power, and the surface facing the object side is convex;

[0006] The second lens is a negative concave-convex lens;

[0007] The third lens is a biconvex lens with positive optical power;

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

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

[0010] The ratio of the focal lengths of the first to fifth lenses to the effective focal length of the optical system satisfies the following set relationship:

[0011] 1.65<|f1 / f|<1.85, 78<|f2 / f|<83, 1.1<|f3 / f|<1.6, 3.2<|f4 / f|<4.0, 11<|f5 / f|<12;

[0012] Wherein, 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, and f represents the effective focal length of the optical system.

[0013] In some embodiments, the refractive index of the first lens, the second lens, the fourth lens, and the fifth lens is greater than 1.45 and less than 1.6; the Abbe coefficient of the second lens, the fourth lens, and the fifth lens is greater than 50 and less than 62.

[0014] In some embodiments, the total optical length of the optical system satisfies 9 mm ≤ TTL ≤ 10 mm, where TTL represents an axial distance from the object-side surface of the first lens to the image plane.

[0015] In some embodiments, the aperture value of the optical system satisfies 1.0≤F.NO≤1.2.

[0016] In some embodiments, the optical back focal length BFL and the effective focal length f of the optical system satisfy the condition: 1.3>BFL / f>0.8, where BFL represents the axial distance from the image-side surface of the fifth lens to the image plane.

[0017] In some embodiments, the optical system satisfies the following condition: 0.7<(h / 2) / (f×tan(FOV / 2))<1.2, where h represents the maximum image circle diameter of the optical system, and FOV represents the maximum field of view angle of the optical system.

[0018] 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 concave surface facing the object side, and a convex surface facing the image side; the third lens has convex surfaces facing both the object side and the image side; the fourth lens has a concave surface facing the object side, and a convex surface facing the image side; the fifth lens has a concave surface facing the object side, and a convex surface facing the image side.

[0019] In some embodiments, it is suitable for imaging at an infrared wavelength of 940 nm and has an operating temperature range of -40°C to 95°C.

[0020] In summary, the present invention has the following beneficial effects:

[0021] This invention provides a miniaturized, large-aperture time-of-flight (TOF) optical system for in-cabin gesture recognition. Through a unique lens combination design, this system achieves a compact structure less than 10mm in length while simultaneously achieving a large aperture of F1.2, significantly enhancing light collection and imaging quality. Specifically, this system is optimized for the 940nm infrared wavelength, ensuring accurate and stable gesture recognition, making it particularly suitable for complex in-vehicle lighting conditions. Furthermore, the system's 2G3P (two glass and three plastic) material combination provides excellent thermal compensation and maintains stable performance over a wide temperature range of -40°C to 95°C. This innovative design not only enhances the system's thermal stability but also achieves an optimal balance between reliability and cost. The benefits of this invention are reflected in its miniaturized design, large-aperture imaging, specific wavelength optimization, and excellent thermal stability, providing an ideal optical solution for in-vehicle gesture recognition applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of a lens according to an embodiment of the present invention;

[0023] Figure 2 This is the MTF analysis chart of 60lp / mm at 20°C for an infrared wavelength of 940nm according to an embodiment of the present invention;

[0024] Figure 3 This is a defocus curve of 60lp / mm at 20°C for an infrared wavelength of 940nm according to an embodiment of the present invention;

[0025] Figure 4 This is a defocus curve of 60lp / mm at 85°C with an infrared wavelength of 940nm according to an embodiment of the present invention;

[0026] Figure 5 This is a defocus curve of 60lp / mm at -40°C for an infrared wavelength of 940nm according to an embodiment of the present invention;

[0027] Figure 6 This is a field curvature diagram of the infrared 940nm wavelength according to an embodiment of the present invention;

[0028] Figure 7 This is the F-THETA distortion diagram of the infrared 940nm wavelength according to the embodiment of the present invention;

[0029] Figure 8 This is the imaging point diagram of the infrared 940nm wavelength according to the embodiment of the present invention.

[0030] In the figure: E1: first lens; E2: second lens; STO (Stop): aperture; E3: third lens; E4: fourth lens; E5: fifth lens; IR (Infrared Filter): filter; CG (Coverglass): protective glass; IMA (Image Surface): image surface;

[0031] 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; S6: The side of the third lens facing the object side; S7: The side of the third lens facing the image side; S8: The side of the fourth lens facing the object side; S9: The side of the fourth lens facing the image side; S10: The side of the fifth lens facing the object side; S11: The side of the fifth lens facing the image side. DETAILED DESCRIPTION

[0032] The following describes embodiments of the present invention in detail, examples of which 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 are not to be construed as limiting the present invention.

[0033] 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, rather than indicating or implying 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 limiting the present invention.

[0034] 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 the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0035] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0036] The following describes an embodiment of an optical system according to an embodiment of the present invention. It should be noted that the data listed in Tables 1 and 2 below are preferred data for the present invention and are not intended to limit the present invention. Any person skilled in the art, after referring to the present invention, may make appropriate changes to the parameters or settings, and such changes will still fall within the scope of the present invention.

[0037] In this embodiment, the parameters of the lens assembly are listed in Table 1:

[0038]

[0039] Table 1

[0040] Aspheric coefficients are shown in Table 2:

[0041]

[0042] Table 2

[0043] The aspheric coefficients satisfy the following equation:

[0044]

[0045] 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.

[0046] Specifically, the R value and thickness of each lens surface in this embodiment are shown in Table 1, and the aspheric surface parameters are shown in Table 2.

[0047] Table 1 shows an effective focal length of 2.53 mm, a total length of 10 mm, an aperture F.NO of 1.2, a full image height of 4.5 mm, and a field of view (2w) of 100.5 degrees. In Table 1, surface numbers S1 and S2 represent the two surfaces of the first lens element E1 along the direction of light incidence; surface numbers S3 and S4 represent the two surfaces of the second lens element E2 along the direction of light incidence; surface numbers S6 and S7 represent the two surfaces of the third lens element E3 along the direction of light incidence; surface numbers S8 and S9 represent the two surfaces of the fourth lens element E4 along the direction of light incidence; and surface numbers S10 and S11 represent the two surfaces of the fifth lens element E5 along the direction of light incidence.

[0048] In this embodiment of the present invention, the first lens E1 is a meniscus lens with negative optical power; the second lens E2 is a meniscus lens with negative optical power; the third lens E3 is a biconvex lens with positive optical power; the fourth lens E4 is a meniscus lens with positive optical power; and the fifth lens E5 is a meniscus lens with positive optical power.

[0049] The ratio of the focal length of the first lens E1 to the fifth lens E5 to the focal length of the lens satisfies the following relationship:

[0050] 1.65<|f1 / f|<1.85, 78<|f2 / f|<83, 1.1<|f3 / f|<1.6, 3.2<|f4 / f|<4.0, 11<|f5 / f|<12; wherein f1 represents the effective focal length of the first lens E1, f2 represents the effective focal length of the second lens E2, f3 represents the effective focal length of the third lens E3, f4 represents the effective focal length of the fourth lens E4, f5 represents the effective focal length of the fifth lens E5, and f represents the effective focal length of the optical system.

[0051] The refractive indices of the first lens E1, the second lens E2, the fourth lens E4, and the fifth lens E5 described in this embodiment of the present invention are all greater than 1.45 and less than 1.6; the Abbe coefficients of the second lens E2, the fourth lens E4, and the fifth lens E5 are all greater than 50 and less than 62.

[0052] In the optical system described in the embodiment of the present invention, the total optical length of the optical system is: 9mm≤TTL≤10mm.

[0053] In the optical system described in the embodiment of the present invention, the aperture value of the optical system is: 1.0≤F.NO≤1.2.

[0054] In the optical system of the embodiment of the present invention, the optical back focal length BFL and the effective focal length f of the optical system satisfy the conditional formula: 1.3>BFL / f>0.8.

[0055] In the optical system described in the embodiment of the present invention, the optical system satisfies the following condition: 0.7<(h / 2) / (f×tan(FOV / 2))<1.2.

[0056] 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.

[0057] The first lens element E1 described in this embodiment of the present invention has a convex surface facing the object side and a concave surface facing the image side; the second lens element E2 has a concave surface facing the object side and a convex surface facing the image side; the third lens element E3 has a convex surface facing the object side and a convex surface facing the image side; the fourth lens element E4 has a concave surface facing the object side and a convex surface facing the image side; and the fifth lens element E5 has a concave surface facing the object side and a convex surface facing the image side.

[0058] In an embodiment of the present invention, Figure 2 The modulation transfer function (MTF) curve of the infrared light band represents the comprehensive resolution capability of the optical system. The horizontal axis represents the spatial frequency (cycles / mm), and the vertical axis represents the value of the modulation transfer function (MTF). The MTF value is used to evaluate the imaging quality of the lens, and the value 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 2 It can be seen that when the spatial frequency of the infrared light band is 60lp / mm, the MTF of the imaging area near the center is greater than 0.7, and the imaging quality is good. Figure 3 From the defocus curve, we can see that the MTF concentration of this lens is good, which makes focusing easy. Figure 4 and Figure 5 It can be seen that the defocus curves at both high and low temperatures meet high resolution, the focus change of the defocus curve is small, and the thermal drift effect is stable; Figure 6 Represented as a field curvature diagram, 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 imaging quality of the lens. Figure 7 It is expressed as F-THETA distortion diagram. The smaller the F-THETA distortion, the smaller the compression of the image edge. Figure 8 Expressed as an imaging point diagram, the more concentrated the image points are, the smaller the lens aberration is and the better the clarity is.

[0059] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed. However, as long as such modifications are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A miniaturized large aperture TOF optical system for in-cabin gesture recognition, characterized by: The optical system comprises five lenses arranged from the object side to the image side, an aperture, a filter, a protective glass, and an image plane. The five lenses are, in order from the object side to the image side, a first lens, a second lens, a third lens, a fourth lens, and a fifth lens. The aperture is located between the second lens and the third lens. The first lens is a meniscus lens with negative optical power, and the surface facing the object side is convex; The second lens is a negative concave-convex lens; The third lens is a biconvex lens with positive optical power; The fourth lens is a meniscus lens with positive optical power; The fifth lens is a meniscus lens with positive optical power; The ratio of the focal lengths of the first to fifth lenses to the effective focal length of the optical system satisfies the following set relationship: 1.65<|f1 / f|<1.85, 78<|f2 / f|<83, 1.1<|f3 / f|<1.6, 3.2<|f4 / f|<4.0, 11<|f5 / f|<12; Wherein, 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, and f represents the effective focal length of the optical system; 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 convex surfaces facing both the object side and the image side; the fourth lens has a concave surface facing the object side, and a convex surface facing the image side; the fifth lens has a concave surface facing the object side, and a convex surface facing the image side.

2. The miniaturized large aperture TOF optical system for in-cabin gesture recognition according to claim 1, characterized in that: The refractive indices of the first lens, the second lens, the fourth lens, and the fifth lens are all greater than 1.45 and less than 1.6; the Abbe coefficients of the second lens, the fourth lens, and the fifth lens are all greater than 50 and less than 62.

3. The miniaturized large aperture TOF optical system for in-cabin gesture recognition according to claim 1, characterized in that: The total optical length of the optical system satisfies 9 mm ≤ TTL ≤ 10 mm, where TTL represents an axial distance from the object-side surface of the first lens to the image plane.

4. The miniaturized large aperture TOF optical system for in-cabin gesture recognition according to claim 1, characterized in that: The aperture value of the optical system satisfies 1.0≤FNO≤1.

2.

5. The miniaturized large aperture TOF optical system for in-cabin gesture recognition according to claim 1, characterized in that: The optical back focal length BFL and the effective focal length f of the optical system satisfy the conditional formula: 1.3>BFL / f>0.8, where BFL represents the axial distance from the image-side surface of the fifth lens to the image plane.

6. The miniaturized large aperture TOF optical system for in-cabin gesture recognition according to claim 1, characterized in that: The optical system satisfies the following condition: 0.7<(h / 2) / (f×tan(FOV / 2))<1.2, where h represents the maximum image circle diameter of the optical system, and FOV represents the maximum field of view angle of the optical system.

7. The miniaturized large aperture TOF optical system for in-cabin gesture recognition according to claim 1, characterized in that: It is suitable for infrared imaging at a wavelength of 940nm and has an operating temperature range of -40℃ to 95℃.

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