Optical systems for vehicles equipped with cameras
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- VALEO VISION SA
- Filing Date
- 2023-06-06
- Publication Date
- 2026-08-03
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to an optical system for a vehicle equipped with a camera. It can be applied particularly to motor vehicles, but is not limited thereto.
Summary of the Invention
[0002] In the field of motor vehicles, optical systems for vehicles known to those skilled in the art comprise the following: - A camera configured to acquire an image of the environment outside the vehicle, - A protective outer lens configured to be arranged facing the camera, the protective outer lens comprising an outer surface facing the outside of the vehicle and an inner surface facing the camera.
[0003] The protective outer lens is configured to hide the camera so that it is not visible from outside the vehicle.
[0004] The drawback of this prior art is that due to the curved shape and / or the semi-transparency or opacity of the protective outer lens, the protective outer lens affects the performance of the camera.
[0005] In relation to this, the present invention aims to propose an optical system for a vehicle equipped with a camera that solves the described drawbacks.
[0006] [[ID=,ID=32]]For this purpose, the invention comprises - A camera configured to acquire an image of the environment outside the vehicle, and - A protective outer lens configured to be arranged facing the camera, the protective outer lens comprising an outer surface facing the outside of the vehicle and an inner surface facing the camera, and The inner surface of the protective outer lens is characterized in that it has a local radius of curvature R2 such that the protective outer lens has a focal length that tends toward infinity. We propose an optical system for vehicles.
[0007] Thus, as will be explained in detail below, determining the local radius of curvature so that the focal length of the protective outer lens approaches infinity provides an optically neutral protective outer lens, and in this way does not degrade the camera's performance level.
[0008] According to non-limiting embodiments, the optical system may further include one or more of the following additional features, which are implemented individually or in any technically possible combination:
[0009] According to one non-limiting embodiment, the local radius of curvature R2 is given by R2 = R1 - (n-1)d / n, where R1 is the local radius of curvature of the outer surface, d is the local thickness of the protective outer lens, and n is the refractive index of the protective outer lens.
[0010] According to one non-limiting embodiment, the camera is an RGB or infrared camera.
[0011] According to one non-limiting embodiment, the outer surface has a set of local radii of curvature R1.
[0012] According to one non-limiting embodiment, the inner surface has a set of local radii of curvature R2.
[0013] A protective outer lens for a vehicle has also been proposed, configured to be positioned to face a camera mounted on the vehicle, the protective outer lens comprising an outer surface facing the outside of the vehicle and an inner surface facing the camera, The inner surface of the protective outer lens is characterized by having a local radius of curvature R2 such that the protective outer lens has a focal length that tends toward infinity.
[0014] According to non-limiting embodiments, the protective outer lens may further include one or more of the following additional features, which are implemented individually or in any technically possible combination:
[0015] According to one non-limiting embodiment, the local radius of curvature R2 is given by R2 = R1 - (n-1)d / n, where R1 is the local radius of curvature of the outer surface, d is the local thickness of the protective outer lens, and n is the refractive index of the protective outer lens.
[0016] According to one non-limiting embodiment, the outer surface has a set of local radii of curvature R1.
[0017] According to one non-limiting embodiment, the inner surface has a set of local radii of curvature R2.
[0018] The invention and its various applications will be better understood by reading the following description and examining the attached diagrams: [Brief explanation of the drawing]
[0019] [Figure 1] Figure 1 shows an optical system for a vehicle according to a non-limiting embodiment of the invention, comprising a camera and a protective outer lens positioned to face the camera, wherein the protective outer lens comprises an outer surface and an inner surface. [Figure 2] Figure 2 shows the infinite focal length of the protective lens of the optical system of Figure 1, compared to a shorter focal length of the prior art, according to a non-limiting embodiment. [Figure 3] Figure 3 shows the optical transfer function curve of a camera in a prior art optical system without a protective outer lens. [Figure 4]FIG. 4 shows the optical transfer function curve of a camera having a protective outer lens of the optical system of FIG. 1. [Figure 5] FIG. 5 shows the optical transfer function curve of a camera of a prior art optical system having a protective outer lens.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Elements that are structurally or functionally identical and appear in multiple figures are given the same reference numeral unless otherwise noted.
[0021] The vehicle optical system 1 according to the invention will be described with reference to FIGS. 1 to 5. In a non-limiting embodiment, the vehicle 2 is an automotive vehicle. An automotive vehicle means any kind of motor vehicle. This embodiment is considered as a non-limiting example in the remainder of the specification. Thus, in the remainder of the specification, the vehicle 2 is also referred to as the automotive vehicle 2. The automotive vehicle 2 comprises the optical system 1.
[0022] As shown in FIG. 1, the optical system 1 comprises the following: - A camera 10 configured to acquire an image I1 of the environment outside the automotive vehicle 2, wherein the acquisition of the image I1 is performed at the image focus f' of the optical system 100 of the camera 10, the camera 10, - A protective lens 11 configured to be disposed facing the camera 10.
[0023] <照 In a non-limiting embodiment, the optical system 1 is incorporated in the following: - A logo, - A rotating logo, - A rearview mirror, - A third brake light called a center high mount stop lamp (CHSML), - In a trunk bar, - In a front-end grille of the automotive vehicle 2, - At the rear of the automotive vehicle 2.
[0024] When the optical system 1 is incorporated into a logo or a rotating logo, the protective outer lens 11 forms part of the logo or the rotating logo.
[0025] In a non-limiting embodiment, camera 10 is an RGB camera or an infrared camera. In a non-limiting embodiment, camera 10 is a FishEye TM This is a camera. In an unspecified example, a ray L1 (shown in Figure 1) from an external light source such as natural light illuminates the scene outside the automobile vehicle 2, and the optical system of the camera 10 makes it possible to view the scene by acquiring an image I1 of the scene.
[0026] In a non-limiting embodiment, camera 10 is used as follows: - Parking assist function known as "rear view" or "surround view" (in non-specific cases, within a range of 0-30 meters), - Rearview mirror function (in non-specific cases, within a range of approximately 80-200 meters).
[0027] The protective outer lens 11 is configured to conceal the camera 10 from the outside of the automobile vehicle 2, but it is also possible to define a standardized shape specific to the automobile vehicle manufacturer. In non-limiting embodiments, it may be translucent, opaque, or transparent.
[0028] The protective outer lens 11 has a focal point F, a focal length f, and a field of view FOV (shown in Figure 2). The protective outer lens 11 also has a thickness d. The protective outer lens 11 comprises an outer surface 11.1 that faces the outside of the automobile vehicle 2 and an inner surface 11.2 that faces the camera 10.
[0029] In a non-limiting embodiment, the outer surface 11.1 is convex while the inner surface 11.2 is concave, or vice versa. In another non-limiting embodiment, both the outer surface 11.1 and the inner surface 11.2 are convex, or both the outer surface 11.1 and the inner surface 11.2 are concave.
[0030] In one non-limiting embodiment, the protective outer lens 11 is made of polycarbonate (PC). Unlike PMMA (polymethyl methacrylate), PC provides a robust outer surface that does not break. In another non-limiting embodiment, the protective lens 11 is made of PMMA.
[0031] The stylized shape of the protective outer lens 11 means that its outer surface 11.1 has a set of multiple local radii of curvature R1 determined by the stylized shape. The inner surface 11.2 has a set of multiple local radii of curvature R2 that are adapted to the various multiple local radii of curvature R1 of the outer surface 11.1.
[0032] The thickness d of the protective outer lens 11 and the radius of curvature R2 of the inner surface 11.2 are varied to maximize the focal length f of the protective outer lens 11. This provides an optically neutral protective outer lens 11. Therefore, the focal length f tends towards infinity to avoid deflection of external light rays L1 onto the camera 10. In fact, if the light rays L1 are deflected, this distorts the image I1 acquired by the camera 10, resulting in a less sharp image I1.
[0033] The definition of focal length f is as follows:
number
[0034] Based on the formula in [Calculation 1], when the focal length f tends toward infinity, the inner surface 11.2 of the protective outer lens 11 has a local radius of curvature R2 such that R2 = R1 - (n-1)d / n. Therefore, the internal local radius of curvature R2 is always smaller than the external local radius of curvature R1.
[0035] This provides an optically neutral protective outer lens 11, which retains the manufacturer's standardized shape because the outer surface 11.1 is not modified.
[0036] In a non-specific example, the protective outer lens 11 has the following features: - The refractive index of light with respect to the polycarbonate protective outer lens 11 is equal to 1.58. - The thickness d is 2.5 mm (millimeters). - At the bottom of the protective outer lens 11, the external local radius of curvature R1 is equal to 150 mm. - At the center of the protective outer lens 11, the external local radius of curvature R1 is equal to 177 mm, and - At the top of the protective outer lens 11, the external local radius of curvature R1 is equal to 195 mm.
[0037] By substituting the internal local radius of curvature R2 into the equation, we obtain the following: - At the bottom of the protective outer lens 11, the internal local radius of curvature R2 is equal to 149.08 mm. - At the center of the protective outer lens 11, the internal local radius of curvature R2 is equal to 176.08 mm, and - At the top of the protective outer lens 11, the internal local radius of curvature R2 is equal to 194.08 mm.
[0038] Figure 2(a) shows a prior art protective outer lens 31 having a focal length f0 and focal point F0. Figure 2(b) shows a protective outer lens 11 having a focal length f, wherein the inner surface 11.2 has a local radius of curvature R2 = R1 - (n-1)d / n. As shown, the focal length f is greater than the focal length f0. Furthermore, the field of view (FOV) of the protective outer lens 11 is smaller than the field of view (FOV0) of the prior art protective outer lens 31, which means that the light ray L1 is less likely to be deflected and therefore converges further toward the focal point F. Thus, f > f0.
[0039] Figures 3 to 5 show the optical transfer function (OTF) curves for the following, respectively: - Camera 10 without protective outer lens, - A camera 10 positioned to face a protective outer lens 11, which is defined by an internal radius of curvature R2 adapted to have a focal length f that tends toward infinity, - A camera 10 positioned to face a prior art protective outer lens 31 defined by a non-conforming radius of curvature R2.
[0040] These curves correspond to various incident angles (0° to 97°) of the light ray L1 reaching the optical system 100 of the camera 10.
[0041] The optical transfer function curve in Figure 2 is used as a reference.
[0042] The optical transfer function curve is used to evaluate the ability of elements of an optical system, such as a camera with or without a protective outer lens, to restore contrast based on the sharpness of the details of an object, i.e., its ability to transmit the spatial frequency of the object. It is used to evaluate the quality of the optical system 100. Therefore, it can be used to evaluate the ability of a protective outer lens 11 to not degrade the performance level of camera 10 compared to camera 10 without a protective outer lens or with a prior art protective outer lens 31.
[0043] The contrast between 0 and 1 is plotted on the Y-axis of the curve (referenced ct). The spatial frequency of the object is plotted on the X-axis in cycles / millimeter (referenced Spf(cy / mm)). This represents the sharpness of the object's details.
[0044] As shown in Figure 4, with the optimized protective outer lens 11, i.e., with the adapted internal radius of curvature R2, the optical transfer function (OTF) does not degrade at any of the considered incident angles. The resulting curve is almost identical to that in Figure 3, i.e., without the protective outer lens. On the other hand, as shown in Figure 5, this is not the case with the unoptimized protective outer lens 31 according to the prior art, i.e., with an unadapted internal radius of curvature R2, and the resulting curve is completely different from the curve in Figure 3.
[0045] Thus, the protective outer lens 11 of the optical system 1 achieves the same performance level with respect to a camera 10 positioned in the same orientation as a camera 10 without the protective outer lens. Therefore, the protective outer lens 11 does not interfere with the camera 10.
[0046] Of course, the description of the invention is not limited to the embodiments described above or to the field described above.
[0047] The invention described in this manner has, in particular, the following advantages: - This allows camera 10 to be integrated behind the protective outer lens 11 without reducing the performance level of camera 10. - Since it does not alter its outer surface 11.1, it allows it to retain the shaped form given to the protective outer lens 11 by the automobile vehicle manufacturer. - This provides an optically neutral protective outer lens 11 by locally fitting the inner surface 11.2 of the protective outer lens 11. - It is easy to implement.
Claims
1. An optical system (1) for a vehicle (2), - A camera (10) configured to acquire an image (I1) of the environment outside the vehicle (2), - A protective outer lens (11) configured to be positioned facing the camera (10), wherein the protective outer lens (11) comprises an outer surface (11.1) facing the outside of the vehicle (2) and an inner surface (11.2) facing the camera (10), Equipped with, The inner surface (11.2) of the protective outer lens (11) has a local radius of curvature R2 such that the protective outer lens (11) has a focal length (f) that tends toward infinity. The local radius of curvature R2 is given by R2 = R1 - (n-1)d / n, where R1 is the local radius of curvature of the outer surface (11.1), d is the local thickness of the protective outer lens (11), and n is the refractive index of the protective outer lens (11). Optical system (1) for vehicle (2).
2. The optical system (1) according to claim 1, wherein the camera (10) is an RGB camera or an infrared camera.
3. The optical system (1) according to claim 1, wherein the outer surface (11.1) has a plurality of local radii of curvature R1.
4. The optical system (1) according to claim 1, wherein the inner surface (11.2) has a plurality of local radii of curvature R2.
5. A protective outer lens (11) for a vehicle (2), which is configured to be positioned facing a camera (10) mounted on the vehicle (2), and the protective outer lens (11) comprises an outer surface (11.1) facing the outside of the vehicle (2) and an inner surface (11.2) facing the camera (10), The inner surface (11.2) of the protective outer lens (11) has a local radius of curvature R2 such that the protective outer lens (11) has a focal length (f) that tends toward infinity. The local radius of curvature R2 is given by R2 = R1 - (n-1)d / n, where R1 is the local radius of curvature of the outer surface (11.1), d is the local thickness of the protective outer lens (11), and n is the refractive index of the protective outer lens (11). Protective outer lens (11) for vehicle (2).
6. The protective outer lens (11) according to claim 5, wherein the outer surface (11.1) has a plurality of local radii of curvature R1.
7. The protective outer lens (11) according to claim 5 or 6, wherein the inner surface (11.2) has a plurality of local radii of curvature R2.