In-vehicle imaging systems and vehicle window glass
The in-vehicle imaging system addresses the challenge of defogging both wide-angle and telephoto cameras by strategically placing a heating element on the glass plate to prevent fogging and distortion, ensuring clear imaging and driver visibility.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2024-11-27
- Publication Date
- 2026-06-08
AI Technical Summary
Conventional vehicle window glass defogging systems are inadequate for effectively defogging the angular field regions of both wide-angle and telephoto cameras with different focal lengths, leading to impaired imaging performance.
An in-vehicle imaging system with a heating element on the glass plate, positioned to avoid the second field of view region of a telephoto camera and the area below the first field of view region of a wide-angle camera, ensuring appropriate defogging while minimizing distortion and obstructing the driver's view.
The system effectively prevents fogging in the field of view of both cameras with different focal lengths, maintaining imaging performance and ensuring clear visibility for the driver.
Smart Images
Figure 2026093081000001_ABST
Abstract
Description
Technical Field
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[0001] The present disclosure relates to an in-vehicle imaging system and a vehicle window glass.
Background Art
[0002] Conventionally, it has been known to provide a defogger on a glass plate for a vehicle window (Patent Document 1). In the window glass described in Patent Document 1, heat rays constituting the defogger are arranged so as to surround a wiring prohibited region located within the imaging range of a camera mounted on the vehicle. With such an arrangement, the wiring prohibited region is defogged by the heat rays located around the wiring prohibited region.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In recent years, with the advancement of advanced safety systems such as collision mitigation brakes, it has been proposed to provide two cameras on a vehicle, namely a wide-angle camera with a short focal length and a telephoto camera with a long focal length. In such a vehicle, the angular field region (imaging range) of the camera on the glass plate is a region that combines both the angular field region of the wide-angle camera and the angular field region of the telephoto camera. Therefore, in the conventional technology disclosed in Patent Document 1, the wiring prohibited region becomes wide, and thus it is not possible to appropriately defog the angular field regions of the wide-angle camera and the telephoto camera respectively.
[0005] In view of the above problems, an object of the present disclosure is to enable appropriate defogging of the angular field regions of two cameras having different focal lengths.
Means for Solving the Problems
[0006] The gist of the present disclosure is as follows.
[0007] (1) A first camera and a second camera positioned to capture images through the windows of a vehicle, An in-vehicle imaging system comprising a heating element provided on the glass plate of the aforementioned window glass, The focal length of the first camera is shorter than the focal length of the second camera. The first camera and the second camera are arranged such that the second field of view region, which is the area of the glass plate that overlaps with the field of view range of the second camera, is not located below the first field of view region, which is the area of the glass plate that overlaps with the field of view range of the first camera, and that the first field of view region and the second field of view region have an overlapping portion. An in-vehicle imaging system wherein the heating element is arranged around the overlapping portion excluding the second field of view region and the region of the glass plate located below the first field of view region. (2) The in-vehicle imaging system according to (1) above, wherein the second camera is positioned such that its optical axis is directed upward compared to the optical axis of the first camera. (3) The in-vehicle imaging system according to (2) above, wherein the first camera and the second camera are arranged at the same height. (4) The in-vehicle imaging system according to any one of (1) to (3) above, wherein the heating element is arranged to pass through the first field of view region excluding the overlapping portion. (5) A vehicle window glass to be installed in a vehicle equipped with a first camera and a second camera having a longer focal length than the first camera, A glass plate and The glass plate comprises a heating element arranged on the glass plate, The first camera and the second camera are installed in the vehicle to capture images through the glass plate, The glass plate has a second field of view region which is the area of the glass plate that overlaps with the field of view range of the second camera, and a first field of view region which is the area of the glass plate that overlaps with the field of view range of the first camera. The second field of view region is not located below the first field of view region, and the first field of view region and the second field of view region have an overlapping portion. The electric heating element is arranged around the overlapping portion excluding the second field of view region and the region of the glass plate located below the first field of view region, in a vehicle window glass. [Effects of the Invention]
[0008] According to this disclosure, it becomes possible to properly prevent fogging in the field of view of two cameras with different focal lengths. [Brief explanation of the drawing]
[0009] [Figure 1] Figure 1 is a schematic front view and top cross view showing the configuration around the vehicle's window glass (front windshield). [Figure 2] Figure 2 is a schematic cross-sectional side view showing the configuration around the vehicle's window glass (front windshield). [Figure 3] Figure 3 is a front view showing a magnified portion of the vehicle's window glass. [Figure 4] Figure 4 is a front view similar to Figure 3, showing a magnified portion of the vehicle's window glass. [Figure 5] Figure 5 is a schematic diagram showing the field of view range of a telephoto camera. [Modes for carrying out the invention]
[0010] The embodiments will be described in detail below with reference to the drawings. In the following description, similar components will be given the same reference numeral.
[0011] <Configuration of the in-vehicle imaging system> Referring to FIGS. 1 to 3, an in-vehicle imaging system 1 according to one embodiment will be described. The in-vehicle imaging system 1 is a system mounted on a vehicle 100 (see FIG. 5) for imaging the front of the vehicle 100. FIG. 1 is a front view and a top cross-sectional view schematically showing the configuration around a window glass (front window) 10 for the vehicle 100. Further, FIG. 2 is a cross-sectional side view schematically showing the configuration around the window glass (front window) 10 of the vehicle 100. Further, FIG. 3 is a front view showing an enlarged part of the window glass 10 of the vehicle 100.
[0012] As shown in FIGS. 1 to 3, the in-vehicle imaging system 1 includes a plurality of cameras 21 and 22 arranged to image an image through the window glass 10 of the vehicle 100, and a heating wire 12 provided on a glass plate 11 of the window glass 10.
[0013] The window glass 10 is a front window or a rear window arranged in front of or behind the vehicle 100. The window glass 10 includes a glass plate 11 made of glass and a heating wire 12 attached to the glass plate 11. Details of the heating wire 12 will be described later.
[0014] <Configuration of the camera> The plurality of cameras 21 and 22 are arranged inside the vehicle 100 (inside the vehicle) and image the outside of the vehicle 100 through the window glass 10. In particular, in the present embodiment, the plurality of cameras 21 and 22 image the front of the vehicle 100 through the front window. However, the plurality of cameras 21 and 22 may image the rear of the vehicle 100 through the rear window.
[0015] In particular, in the present embodiment, the in-vehicle imaging system 1 has two types of cameras, a wide-angle camera (first camera) 21 and a telephoto camera (second camera) 22. The wide-angle camera 21 is a camera having a shorter focal length than the telephoto camera 22. Therefore, the angular range 21a of the wide-angle camera 21 (that is, the range in the angular direction imaged by the wide-angle camera 21) is wider than the angular range 22a of the telephoto camera 22 (that is, the range in the angular direction imaged by the telephoto camera 22) (see FIG. 2).
[0016] Note that, in the present embodiment, the in-vehicle imaging system 1 includes two cameras, i.e., a wide-angle camera 21 and a telephoto camera 22. However, if the focal length of some of the plurality of cameras of the in-vehicle imaging system 1 is shorter than that of other cameras, the in-vehicle imaging system 1 may not have both the wide-angle camera and the telephoto camera, or may have three or more cameras. By having a plurality of cameras with different focal lengths in this way, it is possible to provide a driving support system or an automatic driving system capable of performing advanced control.
[0017] As described above, the wide-angle camera 21 and the telephoto camera 22 image the outside of the vehicle 100 through the window glass 10. Therefore, as shown in FIGS. 1 and 2, the angular range 21a of the wide-angle camera 21 overlaps the glass plate 11 in the first angular region 31. Similarly, the angular range 22a of the telephoto camera 22 overlaps the glass plate 11 in the second angular region 32.
[0018] In the present embodiment, the wide-angle camera 21 images a rectangular image. Also, as shown in FIG. 2, the glass plate 11 is inclined with respect to the optical axis X1 of the wide-angle camera 21. Therefore, as shown in FIGS. 1 and 3, the first angular region 31 is a trapezoidal region. Similarly, the telephoto camera 22 images a rectangular image. Also, as shown in FIG. 2, the glass plate 11 is inclined with respect to the optical axis X2 of the telephoto camera 22. Therefore, as shown in FIGS. 1 and 3, the second angular region 32 is also a trapezoidal region.
[0019] Furthermore, in this embodiment, as shown in Figures 1 and 2, the wide-angle camera 21 and the telephoto camera 22 are positioned near the top of the window glass 10, just inside the window glass 10. In addition, the wide-angle camera 21 and the telephoto camera 22 are positioned adjacent to each other near the center in the vehicle width direction. This allows the wide-angle camera 21 and the telephoto camera 22 to more appropriately detect the environment around the vehicle 100, particularly the environment in front of the vehicle 100. As a result, as shown in Figures 1 and 3, the first field of view area 31 of the wide-angle camera 21 and the second field of view area 32 of the telephoto camera 22 partially overlap. That is, the wide-angle camera 21 and the telephoto camera 22 are positioned to have an overlapping portion 33 where the first field of view area 31 of the wide-angle camera 21 and the second field of view area 32 of the telephoto camera 22 overlap.
[0020] Furthermore, in this embodiment, as shown in Figure 2, the wide-angle camera 21 and the telephoto camera 22 are arranged so that their vertical heights (the height direction of the vehicle 100) are approximately the same. In particular, in this embodiment, the lens of the wide-angle camera 21 and the lens of the telephoto camera 22 are positioned at approximately the same height.
[0021] In addition, in this embodiment, as shown in Figure 2, the wide-angle camera 21 and the telephoto camera 22 are arranged such that the optical axis X2 of the telephoto camera 22 is directed upward compared to the optical axis X1 of the wide-angle camera 21. In particular, in this embodiment, the wide-angle camera 21 is arranged so that its optical axis X1 is approximately horizontal, and the telephoto camera 22 is arranged so that its optical axis X2 is directed upward compared to the horizontal.
[0022] In this embodiment, the wide-angle camera 21 and the telephoto camera 22 are positioned at the same height, and the optical axis X2 of the telephoto camera 22 is positioned upward compared to the optical axis X1 of the wide-angle camera 21. As a result, the lower end of the second field of view region 32 of the telephoto camera 22 is positioned above the lower end of the first field of view region 31 of the wide-angle camera 21. In other words, in this embodiment, the wide-angle camera 21 and the telephoto camera 22 are positioned so that the second field of view region 32 of the telephoto camera 22 is positioned below the first field of view region 31 of the wide-angle camera 21.
[0023] Furthermore, the wide-angle camera 21 and the telephoto camera 22 may be arranged in any way as long as they have an overlapping portion 33 where the first field of view area 31 of the wide-angle camera 21 and the second field of view area 32 of the telephoto camera 22 overlap, and the second field of view area 32 of the telephoto camera 22 is not located below the first field of view area 31 of the wide-angle camera 21. Therefore, if the optical axis X2 of the telephoto camera 22 is positioned upwards above the optical axis X1 of the wide-angle camera 21, the wide-angle camera 21 may be positioned so that its optical axis X1 is not horizontal. Also, the wide-angle camera 21 and the telephoto camera 22 do not have to be positioned at the same height; for example, the telephoto camera 22 may be positioned above the wide-angle camera 21. Moreover, the optical axis X2 of the telephoto camera 22 may be positioned parallel to the optical axis X1 of the wide-angle camera 21 or downwards below the optical axis X1 of the wide-angle camera 21.
[0024] <Construction of the heating element> Next, the configuration of the heating element 12 will be described with reference to Figure 3.
[0025] In this case, the glass plate 11 may fog up due to temperature differences between the inside and outside of the vehicle. In particular, if the first field of view area 31 and the second field of view area 32 on the glass plate 11 fog up, it will reduce the imaging performance of the wide-angle camera 21 and the telephoto camera 22. For this reason, in this embodiment, the heating element 12 is used to prevent fogging of the first field of view area 31 and the second field of view area 32.
[0026] In this embodiment, the heating element 12 is printed onto the glass plate 11. The heating element 12 is formed from a conductor, for example, one whose main component is silver.
[0027] As shown in Figure 3, the heating element 12 is equipped with electrode terminals 12a and 12b. The electrode terminals 12a and 12b are connected to a power source. When current flows through the heating element 12 between electrode terminals 12a and 12b, the heating element 12 generates heat. Then, around the heating element 12, the heat is transferred from the heating element 12, causing water droplets on the surface of the glass plate 11 to evaporate, and as a result, the area around the heating element 12 is prevented from fogging.
[0028] Incidentally, anti-fogging using a heating element works by transferring heat from the heating element to the area to be prevented from fogging. Therefore, generally, the heating element is wired to pass through the area to be prevented from fogging. However, when heat from the heating element is transferred to the glass plate 11, a temperature gradient is created in the glass plate 11, causing distortion in the glass plate 11. If such distortion of the glass plate 11 occurs in the camera's field of view area, it may lead to a decrease in the camera's imaging performance. The degree of decrease in the camera's imaging performance due to such distortion of the glass plate 11 varies depending on the characteristics of the camera.
[0029] Here, the wide-angle camera 21 has a short focal length, and therefore the distance between the lens and the image sensor is short. For this reason, even if distortion occurs in the first field of view area 31 of the glass plate 11 positioned in front of the wide-angle camera 21, causing improper refraction of the light passing through, the short focal length means that the resulting shift in light at the image sensor is not very large. Therefore, the effect of distortion in the glass plate 11 on the generated image is relatively small in the wide-angle camera 21.
[0030] On the other hand, the telephoto camera 22 has a long focal length, and therefore the distance between the lens and the image sensor is long. For this reason, if, for example, distortion occurs in the second field of view 32 of the glass plate 11 positioned in front of the telephoto camera 22, causing improper refraction of the light passing through, the long focal length results in a large shift in the light ultimately produced by the image sensor due to this refraction. Consequently, the influence of distortion in the glass plate 11 on the generated image is relatively large in the telephoto camera 22.
[0031] Furthermore, the windows 10 of the vehicle 100, particularly the front windshield, are used by the driver to see the direction of travel while driving the vehicle 100. Therefore, it is preferable that heating wires that obstruct the driver's view are not placed in the area from the center downwards in the vertical direction of the window glass 10. Accordingly, it is preferable that heating wires are not placed in the area below the visibility boundary line 40 in Figures 1 and 3, as this area is intended to ensure the driver's view.
[0032] Therefore, in this embodiment, taking into consideration the impact of distortion of the glass plate 11 on the imaging performance of each camera 21, 22 and the driver's field of view, the heating wire 12 is arranged as follows.
[0033] First, in this embodiment, the heating element 12 is not placed within the second field of view region 32 of the telephoto camera 22. This suppresses the occurrence of large distortions in the glass plate 11 due to temperature gradients within the second field of view region 32 of the telephoto camera 22. As a result, a decrease in the imaging performance of the telephoto camera 22 can be suppressed.
[0034] Furthermore, in this embodiment, the heating element 12 is placed within the first field of view region 31 of the wide-angle camera 21. However, even within the first field of view region 31, the heating element 12 is not placed in the overlapping portion 33 with the second field of view region 32. As can be seen from Figures 1 and 3, the first field of view region 31 is relatively wide, so by heating this first field of view region 31 with the heating element, fogging in the first field of view region can be suppressed. Also, as mentioned above, the influence of distortion in the glass plate 11 on the generated image in the wide-angle camera 21 is relatively small. Therefore, it is possible to prevent fogging in the imaging range of the wide-angle camera 21 while suppressing a decrease in the imaging performance of the wide-angle camera 21.
[0035] In addition, in this embodiment, the heating wire 12 is placed around the overlapping portion 33. As described above, the heating wire 12 is not placed in the second field of view region 32 which includes the overlapping portion 33, but by placing the heating wire 12 around the overlapping portion 33, a certain amount of heat is transferred to the overlapping portion 33. As a result, the overlapping portion 33 is heated, although a temperature gradient large enough to cause significant distortion in the glass plate 11 is not created, thus ensuring anti-fogging performance. In particular, since the second field of view region 32 of the telephoto camera 22 is relatively narrow, simply placing the heating wire 12 around the overlapping portion 33 is sufficient to prevent fogging.
[0036] However, in this embodiment, even around the overlapping portion 33, the heating wire 12 is not placed within the second field of view region 32 of the telephoto camera 22. This suppresses the degradation of the imaging performance of the telephoto camera 22 caused by the placement of the heating wire in the second field of view region 32.
[0037] Furthermore, in this embodiment, even around the overlapping portion 33, the heating wires 12 are not placed in the area below the field of view boundary line 40. In particular, in this embodiment, the lower end of the first field of view region 31 of the wide-angle camera 21 extends to the vicinity of the field of view boundary line 40, or beyond the field of view boundary line 40 (in the example shown in Figure 3, it extends beyond the field of view boundary line 40). Therefore, in this embodiment, even around the overlapping portion 33, the heating wires 12 are not placed in the area of the glass plate 11 located below the first field of view region 31 of the wide-angle camera 21. This suppresses obstruction of the driver's view by the heating wires 12. In this embodiment, the telephoto camera 22 is positioned such that the lower end of its second field of view region 32 does not extend downward beyond the field of view boundary line 40.
[0038] Therefore, in this embodiment, the heating element 12 is arranged around the overlapping portion 33, excluding the area of the glass plate 11 located below the second field of view region 32 and the first field of view region 31, as shown in Figure 3. Alternatively, the heating element 12 may be arranged around the entire overlapping portion 33, excluding the area of the glass plate 11 located below the second field of view region 32 and the first field of view region 31, or it may be arranged around a part of the overlapping portion 33, excluding the area of the glass plate 11 located below the second field of view region 32 and the first field of view region 31.
[0039] <Effects> Incidentally, unlike the above embodiment, when the optical axis X1 of the wide-angle camera 21 and the optical axis X2 of the telephoto camera 22 are parallel, the second field of view area of the telephoto camera 22 may be located lower than in the above embodiment. This is shown in Figure 4. Figure 4 is a front view similar to Figure 3, showing an enlarged portion of the window glass 10 of the vehicle 100.
[0040] If the optical axis X1 of the wide-angle camera 21 and the optical axis X2 of the telephoto camera 22 are made parallel, the second field of view area 32' of the telephoto camera 22 may be located below the first field of view area 31 of the wide-angle camera 21, as shown in Figure 4. In particular, in the example shown in Figure 4, the lower end of the first field of view area 31 of the wide-angle camera 21 extends to the vicinity of the field of view boundary line 40, so the second field of view area 32' of the telephoto camera 22 extends beyond the field of view boundary line 40. Therefore, in this case, if heating wires 12' are to be placed around the second field of view area 32', the heating wires 12' will extend below the field of view boundary line 40, as shown in Figure 4, obstructing the driver's view. On the other hand, if heating wires 12' are not placed around the second field of view area 32' of the telephoto camera 22 in the portion below the field of view boundary line 40 in order to avoid obstructing the driver's view, it will not be possible to properly prevent fogging in the portion of the second field of view area 32' below the field of view boundary line 40.
[0041] In contrast, in the above embodiment, the wide-angle camera 21 and the telephoto camera 22 are arranged such that the second field of view area 32 of the telephoto camera 22 is located below the first field of view area 31 of the wide-angle camera 21. Therefore, the second field of view area 32 of the telephoto camera 22 is not located below the field of view boundary line 40, thereby preventing the heating element from obstructing the driver's view and preventing the portion of the second field of view area below the field of view boundary line 40 from becoming unsuitable for proper fogging prevention.
[0042] Furthermore, in the above embodiment, the wide-angle camera 21 and the telephoto camera 22 are arranged such that the optical axis X2 of the telephoto camera 22 is directed upward compared to the optical axis X1 of the wide-angle camera 21. As a result, the field of view range of the telephoto camera 22 changes compared to the case where the optical axis X1 of the wide-angle camera 21 and the optical axis X2 of the telephoto camera 22 are parallel.
[0043] Figure 5 is a schematic diagram showing the field of view of the telephoto camera 22. In the figure, X2 and 22a indicate the optical axis and field of view of the telephoto camera 22 when its optical axis is pointed upward from the horizontal, respectively. On the other hand, X2' and 22a' in the figure indicate the optical axis and field of view of the telephoto camera 22 when its optical axis is horizontal (parallel to the optical axis X1 of the wide-angle camera 21), respectively.
[0044] Here, the telephoto camera 22 is generally installed to recognize distant traffic lights, signs, and preceding vehicles. As shown in Figure 5, even if the optical axis of the telephoto camera 22 is pointed upward, only a portion of road A will fall outside the field of view, while distant traffic lights, signs, preceding vehicles, etc. will remain within the field of view of the telephoto camera 22. Therefore, although road A, which is not used even if it is imaged, will no longer be imaged, the telephoto camera 22 can still image distant traffic lights, signs, preceding vehicles, etc., and thus the actual impact of pointing the optical axis of the telephoto camera 22 upward is small.
[0045] Furthermore, typically, the wide-angle camera 21 and the telephoto camera 22 are positioned above the rear of the front windshield, often resulting in vertical mounting constraints. In the above embodiment, the wide-angle camera 21 is positioned at the same height as the telephoto camera 22. This minimizes the overall vertical height of the wide-angle camera 21 and the telephoto camera 22, thereby improving mountability.
[0046] While preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to these embodiments, and various modifications and changes can be made within the scope of the claims. [Explanation of Symbols]
[0047] 1. In-vehicle imaging system 10 Windowpanes 11 Glass plate 12 Heating wire 21 Wide-angle camera 22 Telephoto Cameras 31. First field of view region 32 Second field of view region
Claims
1. A first camera and a second camera are positioned to capture images through the vehicle's windows, An in-vehicle imaging system comprising a heating element provided on the glass plate of the aforementioned window glass, The focal length of the first camera is shorter than the focal length of the second camera. The first camera and the second camera are arranged such that the second field of view region, which is the area of the glass plate that overlaps with the field of view range of the second camera, is not located below the first field of view region, which is the area of the glass plate that overlaps with the field of view range of the first camera, and that the first field of view region and the second field of view region have an overlapping portion. An in-vehicle imaging system wherein the heating element is arranged around the overlapping portion excluding the second field of view region and the region of the glass plate located below the first field of view region.
2. The in-vehicle imaging system according to claim 1, wherein the second camera is positioned such that its optical axis is directed upward compared to the optical axis of the first camera.
3. The in-vehicle imaging system according to claim 2, wherein the first camera and the second camera are arranged at the same height.
4. The in-vehicle imaging system according to any one of claims 1 to 3, wherein the heating element is arranged to pass through the first field of view region excluding the overlapping portion.
5. A vehicle window glass to be installed in a vehicle equipped with a first camera and a second camera having a longer focal length than the first camera, A glass plate and The glass plate comprises a heating element arranged on the glass plate, The first camera and the second camera are installed in the vehicle to capture images through the glass plate, The glass plate has a second field of view region which is the area of the glass plate that overlaps with the field of view range of the second camera, and a first field of view region which is the area of the glass plate that overlaps with the field of view range of the first camera. The second field of view region is not located below the first field of view region, and the first field of view region and the second field of view region have an overlapping portion. The electric heating element is arranged around the overlapping portion excluding the second field of view region and the region of the glass plate located below the first field of view region, in a vehicle window glass.