JP5436892B2 - Vehicle imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus for a vehicle that uses an imaging element to determine the presence or absence of raindrops and the brightness of the surroundings of the vehicle.

  Conventionally, a plurality of devices for detecting raindrops attached to a windshield have been proposed (see, for example, Patent Documents 1 and 2). The apparatus of Patent Document 1 irradiates illumination from the lower side of the windshield, and detects changes in the reflectance of the windshield by raindrops with a camera. The apparatus of Patent Document 2 is provided with a translucent screen attached to a windshield, picking up an image near the screen, and determining the presence or absence of raindrops.

  Japanese Patent Application Laid-Open No. H10-228561 describes an apparatus that performs light / dark determination using a raindrop detection sensor and performs automatic light control. As an apparatus for determining brightness, an example using an image sensor has been proposed as described in Patent Document 4, for example.

  Moreover, it is necessary to perform the auto light control not only at night but also at the entrance of the tunnel. Devices that determine the presence or absence of a tunnel and perform autolight control include devices such as Patent Literature 5 and Patent Literature 6. The apparatus of Patent Document 5 uses a prism to make light incident from different directions, and detects the presence or absence of a tunnel by detecting the illuminance in front of the vehicle and around the vehicle with separate photodiodes. Patent Document 6 describes an example in which an illuminance sensor for tunnel detection is provided separately from a normal illuminance sensor for controlling automatic light.

JP 2006-284555 A JP-A-10-90188 JP 2001-206201 A Japanese Patent Laid-Open No. 5-185871 Japanese Utility Model Publication No. 4-48504 JP-A-2005-199974

  It is an object of the present invention to provide a vehicular image pickup apparatus that can determine the presence / absence of raindrops and brightness / darkness with high accuracy while using both a raindrop sensor and an autolight sensor in one image pickup apparatus.

An imaging apparatus for a vehicle according to the present invention includes an imaging means having a first imaging area and a second imaging area installed in a vehicle interior toward a windshield, and is reflected in the vehicle interior and reflected through the windshield. In the vehicle imaging device, comprising: an illuminating unit that irradiates light to the first imaging region; and a light shielding unit provided at a boundary between the first imaging region and the second imaging region. Raindrop determining means for determining presence / absence of raindrops on the windshield based on the imaging information input from the vehicle, and light / dark determination means for determining the lightness / darkness around the vehicle based on the imaging information input from the second imaging area And.

  In this way, the vehicle imaging device divides the imaging area of the imaging means into the first imaging area for raindrop determination and the second imaging area for lightness / darkness determination, and performs the presence / absence of raindrops and light / darkness determination with one imaging means. At this time, by providing the light shielding means at the boundary between the first imaging area and the second imaging area, it is possible to prevent the light from the illumination means from entering the second imaging area and to allow outside light such as the sun to enter the first imaging area. Prevent entry into.

Moreover, in the said invention, you may provide a diffusion plate in the reflective surface of the said windshield in the area | region where the said illumination means irradiates light . By providing the diffusion plate, it is possible to reduce the degree of influence of the background in front of the vehicle on the raindrop determination in the first imaging region.

  In the invention described above, the second imaging area is provided above the first imaging area.

  In the above invention, an optical guide plate is provided in front of the second imaging region, and light in different directions in the vertical direction is input to some imaging regions in the second imaging region. Also good.

  According to the present invention, it is possible to determine the presence / absence of raindrops and brightness / darkness with high accuracy while using both the raindrop sensor and the auto light sensor in one image pickup apparatus.

It is a figure which shows the structure of the imaging device for vehicles. It is a figure which shows the image of the daytime which the camera 11 imaged. It is a figure which shows the image of the evening image which the camera 11 imaged. It is a figure which shows the night image which the camera 11 imaged. It is a flowchart which shows light / dark judgment and shows control of lighting / extinguishing based on the result. It is a figure which shows the image of the tunnel entrance vicinity which the camera 11 imaged. It is a figure which shows the image (presence of raindrops) which the camera 11 imaged. It is a flowchart which shows adhesion of raindrops and shows the control of wiping using a wiper based on the result. It is a figure explaining threshold determination. It is a figure which shows the imaging device for vehicles provided with the light guide. It is a figure explaining a light guide. It is a figure explaining a light guide.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment according to a vehicle imaging device of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of a vehicle imaging device. FIG. 4A is a view of the vehicular imaging device viewed from the side, and FIG. 4B is a view viewed from the front. The vehicular imaging device performs raindrop adhesion determination on the windshield and brightness determination around the vehicle, and performs wiper control and headlamp lighting control (auto light control).

  FIG. 1 (A) and FIG. 1 (B) show an imaging device 1 for a vehicle. FIG. 1A is a side view of the vehicle imaging device 1. FIG. 1B shows a front view of the vehicle imaging device 1. In FIG. 1, an imaging apparatus 1 for a vehicle includes a camera 11 that is imaging means, a lens 12 that makes light from the front of the vehicle incident on the camera 11, a diffuser plate 13 that diffuses incident light from the front of the vehicle, and a partition that is light shielding means. 14, LED16 which is an illumination means, and the control part 17 are provided. The camera 11 and the LED 16 are connected to the control unit 17.

  The vehicular imaging device 1 is mounted in the vicinity of the windshield 2 (for example, the back side of a room mirror, etc.) in the vehicle interior. The imaging area of the camera 11 is directed to the front of the vehicle. The diffusion plate 13 is attached along the windshield 2 so as to cover a part of the imaging region of the camera 11 (the lower half in this embodiment). The diffusion plate 13 may be adhered to the reflection surface of the windshield 2 or may be embedded in the windshield near the reflection surface. Further, the lens 12 is focused on the vicinity of the windshield 2.

  The lower half of the imaging area of the camera 11 (area covered by the diffuser) is the raindrop adhesion determination area (first imaging area of the present invention). Further, the upper half of the imaging area of the camera 11 is a light / dark determination area (second imaging area of the present invention). The raindrop adhesion determination area and the light / dark determination area may be the same area, or one of them may be wide.

  Moreover, the partition 14 is installed from the windshield 2 to the lens 12 along the boundary between the raindrop adhesion determination area and the light / dark determination area. LED16 irradiates the light for illuminating the raindrop adhering to the windshield 2, and is mainly used for the raindrop adhesion determination at night. The vehicular imaging apparatus 1 according to the present embodiment prevents the light from the LED 16 from entering the light / dark determination region and the outside light such as the sun from entering the raindrop adhesion determination region by the partition 14. Yes.

  FIG. 2 is a diagram illustrating a daytime image captured by the camera 11. FIG. 3 is a diagram illustrating an evening image captured by the camera 11, and FIG. 4 is a diagram illustrating a night image captured by the camera 11. As shown in FIGS. 2 to 4, in the lower half of the imaging area of the camera 11, incident light from the front of the vehicle is diffused and transmitted by the diffusion plate 13, so that an image in front of the vehicle is not captured. In addition, since the lens 12 is focused near the windshield 2, raindrops attached to the windshield 2 are clearly imaged (see FIG. 7B). Therefore, the vehicular imaging apparatus 1 according to the present embodiment can accurately perform raindrop adhesion determination.

  Further, in the upper half of the imaging area of the camera 11, the lens 12 is focused on the vicinity of the windshield 2, so an image in front of the vehicle is blurred. As will be described later, the control unit 17 performs only image processing for brightness in the light / dark determination region. Even if the lens 12 is out of focus from the front of the vehicle, the brightness image processing is not affected and the brightness determination can be performed with high accuracy.

  An image (imaging information) captured by the camera 11 is input to the control unit 17. The control unit 17 performs raindrop adhesion determination and light / dark determination from the input image. First, the brightness determination will be described. FIG. 5 is a flowchart showing control of lighting / extinguishing of the vehicle width lamp / headlight based on the result of determination of light and dark.

  First, the control unit 17 acquires an image from the camera 11 (s11). And the control part 17 cuts out the upper half (brightness determination area | region) of the input image, and performs an image average process (s12). The image averaging process is a process of calculating the brightness for each predetermined region composed of a plurality of pixels (maximum for each pixel unit of the image sensor) and calculating the average value of the calculated brightness. Thereafter, the control unit 17 determines daytime, evening, and nighttime from the calculated average value, and performs autolight control.

  That is, the control unit 17 determines whether or not the average value calculated in the image average process is larger than the threshold value A (s13). When the average value is larger than the threshold value A, the control unit 17 determines that it is daytime and turns off the vehicle lights (the vehicle width lamp and the headlamp) (s14).

  On the other hand, when determining that the average value is equal to or less than the threshold value A, the control unit 17 further determines whether or not the average value is greater than the threshold value B (provided that A> B) (s15). When the average value is larger than the threshold value B, the control unit 17 determines that it is evening, and turns on the vehicle width lamp (s16). Moreover, when it determines with the average value being the threshold value B or less, the control part 17 determines with it being night and turns on a headlamp (s17).

  Note that the light / dark determination method is not limited to the above example. For example, if the brightness of each predetermined area is equal to or greater than a threshold value, it is determined as “bright”, and if it is less than the threshold value, it is determined as “dark”, and the number of pixels determined as “bright” or “dark” Brightness / darkness determination may be performed based on the number of pixels determined as.

  Moreover, the control part 17 can also determine the presence or absence of a tunnel. FIG. 6 is a diagram showing an image near the tunnel entrance taken by the camera 11. If there is a tunnel in front of the vehicle, an image that is partially determined as “bright” and partially determined as “dark” is captured. Therefore, for example, when an image in which “bright” and “dark” alternately exist is input, the control unit 17 determines that there is a tunnel ahead and lights the headlamp. In this case, the headlamp can be turned on before entering the tunnel.

  Next, raindrop adhesion determination will be described. FIG. 7 is a diagram illustrating an image (presence or absence of raindrops) captured by the camera 11. FIG. 3A shows an image captured by the camera 11 in fine weather, and shows a case where no raindrops are attached to the windshield 2. FIG. 5B is an image captured by the camera 11 when it rains, and shows a case where raindrops adhere to the windshield 2. As shown in FIG. 5B, the focus of the lens 12 is adjusted to the vicinity of the windshield 2, so that the attached raindrop is clearly imaged.

  FIG. 8 is a flowchart showing control of wiping using a wiper based on the result of determining the adhesion of raindrops. First, the control unit 17 acquires an image from the camera 11 (s21). Then, the control unit 17 cuts out the lower half (raindrop adhesion determination region) of the input image and performs filter processing such as edge enhancement (s22). The control unit 17 performs threshold processing after the filter processing (s23).

  FIG. 9 is a diagram illustrating threshold processing. The horizontal axis of the histograms shown in FIGS. 4A and 4B is a pixel value (intermediate value is 0, and 256 gradations from −128 to 127). FIG. 2A shows a histogram in fine weather, and FIG. 2B shows a histogram in rainy weather.

  In the case of fine weather, nothing is imaged in the raindrop adhesion determination area, so the pixel values are concentrated around ± 0. On the other hand, in the case of rain, the light of the LED 16 is diffusely reflected, and a plurality of pixel values exceeding the threshold (greater than the threshold Th1 or smaller than the threshold Th2) appear. Therefore, in the threshold processing, the control unit 17 obtains a pixel value for each predetermined region composed of a plurality of pixels (maximum for each pixel unit of the image sensor), and counts the number of regions exceeding the threshold.

  Next, in FIG. 8, the control unit 17 determines whether or not the counted number of regions is smaller than the threshold value C (s24). If the counted number of areas is smaller than the threshold value C, the control unit 17 determines that no raindrops are attached to the windshield 2 and turns off the wiper (s25). When determining that the number of counted areas is equal to or greater than the threshold value C, the control unit 17 further determines whether or not it is smaller than the threshold value D (provided that C <D) (s26). When it is smaller than the threshold value D, the control unit 17 determines that it is a time when raindrops adhere and the amount of rain is small, and the wiper is operated intermittently (s27). When determining that the number of areas counted is equal to or greater than the threshold value D, the control unit 17 further determines whether or not it is smaller than the threshold value E (provided that D <E) (s28). When it is smaller than the threshold value E, the control unit 17 determines that it is a time when raindrops are attached and the amount of rain is large, and makes the wiper operate continuously (s29). If the number of areas counted is equal to or greater than the threshold value E, the control unit 17 determines that it is a time when raindrops are attached and the rain is heavy, and causes the wiper to operate at high speed (s30).

  As described above, the vehicle imaging apparatus 1 of the present embodiment performs raindrop adhesion determination and light / dark determination with a single image sensor. The brightness of the LED is greatly different from that in front of the vehicle (sunlight or the like), and conventionally, it has been difficult to adjust the light emission of the LED and the image sensor of the camera. However, in the vehicle imaging device of the present invention, the light emitted from the LED is not irradiated to the light / dark determination region, and external light from the light / dark determination region is not irradiated to the raindrop adhesion determination region. And light / dark judgment can be realized with high accuracy.

  Although the diffusion plate 13 is not essential in the present invention, the processing load of raindrop adhesion determination in the control unit 17 is reduced by the diffusion plate 13 functioning as a hardware filter that blocks the background in front of the vehicle.

  Next, FIG. 10 is a diagram illustrating a vehicle imaging device including a light guide 15 that is an optical guide plate. Components that are the same as those in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted.

  In FIG. 10, in the vehicle imaging device 1, the light guide 15 is installed in front of the lens 12. The light guide 15 has a function of guiding light from the outside to the lens 12. In the drawing, the light guide 15 has a lens-like cross-sectional shape, but is not limited to this shape, and may have a prism (trapezoidal) cross-sectional shape.

  FIG. 11 is a diagram illustrating the function of the light guide 15. As shown in FIG. 11A, in this example, the light / dark determination region is divided into three regions, the center, the left side, and the right side, and the light from the light guide 15 is incident on the left side and the right side. doing. In this case, light in the upward direction of the vehicle is incident on the left and right sides of the light / dark determination region. That is, as shown in FIG. 5B, the light guide 15 has a convex shape in the downward direction, so that light in the forward direction of the vehicle is incident on the lens 12. As a result, the camera 11 captures an image in the upper front direction of the vehicle (the image is turned upside down). Therefore, the control unit 17 can simultaneously determine the brightness of the front front direction and the upward direction of the vehicle, and can perform auto light control with higher accuracy.

  Next, FIG. 12 is a diagram illustrating an example where the shape of the light guide 15 is different. Also in this example, the light / dark determination region is divided into a central region, a left region, and a right region, and the light from the light guide 15 is incident on the center. In this case, light in the vehicle front lower direction enters the center of the light / dark determination region. That is, as shown in FIG. 5B, since the light guide 15 has a convex shape upward, light in the vehicle front downward direction is incident on the lens 12. As a result, the camera 11 captures an image in the lower front direction of the vehicle (the image is turned upside down). In this case, an image in the downward direction (road surface) can be taken avoiding the diffusion plate 13. Therefore, the control part 17 can perform the brightness determination of the front front of a vehicle and a road surface simultaneously, and can perform auto light control with still higher precision.

  Further, when the light guide shown in FIGS. 11 and 12 is used, the light / dark determination (determination of tunnel existence) in the vicinity of the entrance of the tunnel can be realized with higher accuracy. That is, since it is possible to simultaneously perform the light / dark determination in front of the vehicle, in the upward direction, and in the vicinity of the road surface, for example, when the front surface in front of the vehicle is dark and the upward direction and in the vicinity of the road surface are bright, it is determined that the vehicle is immediately before entering the tunnel. be able to.

  When the light guide shown in FIGS. 11 and 12 is used, the light shielding means is not limited to the shape of the partition 14, and may be one that shields the lower part of the light guide.

1-Laser radar 11-Camera 12-Lens 13-Diffusion plate 14-Partition 15-Light guide 16-LED
17-Control part

Claims (4)

An imaging means having a first imaging area and a second imaging area installed in the passenger compartment toward the windshield;
An illuminating means installed in the vehicle interior, reflected through the windshield, and irradiating the first imaging area with light;
A light shielding means provided at a boundary between the first imaging region and the second imaging region;
In a vehicle imaging device comprising:
Raindrop determination means for determining presence or absence of raindrops on the windshield based on imaging information input from the first imaging region;
Light / dark determination means for determining light and dark surrounding the vehicle based on the image pickup information input from the second image pickup area;
An imaging apparatus for a vehicle, comprising: 2. The vehicular imaging apparatus according to claim 1, wherein a diffusion plate is provided on a reflection surface of the windshield in a region where the illumination unit irradiates light .   The vehicular imaging apparatus according to claim 1, wherein the second imaging area is provided in an upward direction with respect to the first imaging area.   2. An optical guide plate is provided in front of the second imaging region, and light in a different direction in the vertical direction is input to some imaging regions in the second imaging region. The vehicle imaging device according to claim 2 or claim 3.