JP5136071B2 - Vehicle rear monitoring device and vehicle rear monitoring method - Google Patents

Description

  The present invention relates to a vehicle rear monitoring apparatus and a vehicle rear monitoring method for displaying an image of a vehicle rear on a display means and presenting the image to a vehicle occupant.

Conventionally, as this type of vehicle rear monitoring device, a camera capable of changing the focal length of the lens is installed at the rear of the vehicle, and when the vehicle is moving backward, a short-focus and wide-angle image is captured and displayed on the monitor. There has been proposed a technique in which a video with a long focus and a standard angle of view is captured by a camera and displayed on a monitor when the vehicle moves forward (see, for example, Patent Document 1).
Japanese Patent No. 2955107

  As in the case of the vehicle rear monitoring apparatus described in Patent Document 1, when a video image captured at a narrower angle of view is displayed on the monitor when the vehicle moves forward, the vehicle occupant can check with the subsequent vehicle that the monitor confirms on the monitor. It is considered that the sense of distance and the sense of speed can be brought closer when confirmed with a room mirror. However, if the image is taken with a narrow angle of view of the camera, the blind spot area that is not captured as an image expands accordingly, so if an obstacle behind the vehicle enters this blind spot area when the vehicle is moving forward, the obstacle behind the vehicle There is a problem that the vehicle occupant cannot be informed that the vehicle is present.

  The present invention was devised to solve the above-described problems of the prior art, and there is an obstacle behind the vehicle while displaying an image that can correctly grasp the sense of distance and speed when the vehicle moves forward. Accordingly, an object of the present invention is to provide a vehicular rearward monitoring apparatus and a vehicle rearward monitoring method that allow a vehicle occupant to recognize the presence of the obstacle.

According to the present invention, among images of a predetermined area behind the vehicle imaged by the image pickup means, an image of an area narrower than the time of the vehicle reverse is extracted as a display target when the vehicle moves forward and displayed on the display means, and is also imaged by the image pickup means. The object is detected by detecting an obstacle behind the vehicle based on a change in luminance pattern of an image that is not extracted as a display target but not displayed on the display means, and notifies the vehicle occupant of the presence of the obstacle. To achieve.

  According to the present invention, when a video of a narrow area behind the vehicle is displayed on the display means when the vehicle moves forward, an obstacle behind the vehicle is detected based on the video imaged by the imaging means but not displayed on the display means. Therefore, when an obstacle exists behind the vehicle, the vehicle occupant can recognize the presence of the obstacle while displaying an image that can correctly grasp the sense of distance and speed when the vehicle moves forward.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of the vehicle rear monitoring apparatus of the present embodiment. As shown in FIG. 1, the rear monitoring apparatus for a vehicle according to the present embodiment includes a rear camera 1 connected to the input side of the video processing unit 10, and a display 2 and a speaker 3 connected to the output side of the video processing unit 10. Composed. In addition, a vehicle speed sensor 4, a shift position sensor 5, a road information acquisition device 6, and an operation input device 7 are connected to the video processing unit 10.

  The rear camera 1 is installed in a predetermined position at the rear of a vehicle (hereinafter referred to as the host vehicle) on which the vehicle rear monitoring device of the present embodiment is mounted, for example, a roof spoiler of the host vehicle, and is installed in a predetermined area behind the host vehicle. Take a picture. The rear camera 1 has an optical system composed of a lens and a light receiving element, receives light incident through the lens by a light receiving element such as a CCD or CMOS, converts the light into an electrical signal, and takes a photographed image for each pixel. Output as a digitized video signal. As the rear camera 1, a wide-angle camera having a wide shooting angle of view is used so that other vehicles (obstacles) approaching the vicinity of the host vehicle are included in the shooting range. The video behind the host vehicle photographed by the rear camera 1 is input to the video processing unit 10 as needed.

  The display 2 is installed at a position that is easy for the driver to see, such as a center console in the passenger compartment of the host vehicle, and displays an image behind the host vehicle based on the video signal output from the video processing unit 10. The speaker 3 is installed at a predetermined position in the passenger compartment of the host vehicle, and outputs a warning sound when an obstacle behind the host vehicle is detected by the video processing unit 10.

  The vehicle speed sensor 4 detects a traveling speed of the host vehicle, and the shift position sensor 5 detects a shift position (gear position) of the host vehicle. Detection signals from the vehicle speed sensor 4 and the shift position sensor 5 are input to the video processing unit 10.

  The road information acquisition device 6 acquires information related to the road on which the host vehicle is traveling. For example, the road information acquisition device 6 detects the position of the host vehicle and performs a map matching function. A communication device that acquires information on the road on which the vehicle is traveling is used. Information acquired by the road information acquisition device 6 is input to the video processing unit 10.

  The operation input device 7 receives an operation input by the driver of the host vehicle, and various operation buttons, a joystick, etc. are used, for example. Further, a touch panel may be provided on the display screen of the display 2 and this touch panel may be used as the operation input device 7. An operation input by the driver of the own vehicle using the operation input device 7 is input to the video processing unit 10.

  The video processing unit 10 includes an information processing device such as a microcomputer in which a predetermined processing program is stored, and the host vehicle photographed by the rear camera 1 by executing this program with an arithmetic device such as a CPU. A rear image is displayed on the display 2 and an obstacle that is not displayed on the display 2 is detected from images captured by the rear camera 1 to detect an obstacle behind the host vehicle and notify the driver of the host vehicle. . As shown in FIG. 2, the video processing unit 10 has a video input unit 11, a display video extraction unit 12, a video output unit 13, an obstacle detection unit 14, The obstacle notification unit 15 is provided.

  The video input unit 11 includes an input buffer corresponding to the frame size of the video shot by the rear camera 1. The data of the video behind the host vehicle photographed by the rear camera 1 is stored in the input buffer of the video input unit 11 while being updated every frame.

  The display video extraction unit 12 extracts a display video to be displayed on the display 2 from the captured video of the rear camera 1 stored in the input buffer of the video input unit 11. Here, the display image extraction unit 12 determines whether the traveling direction of the host vehicle is moving forward or backward based on the detection signal of the shift position sensor 5 or the like. The image of the relatively wide first region is extracted as the display image to be displayed on the display 2 from the image of the predetermined region behind the vehicle, and if the host vehicle is traveling forward, it is more than the first region. The video of the second area, which is a narrow area, is extracted as a display video to be displayed on the display 2.

  Specifically, as shown in FIG. 3, the display image extraction unit 12 is configured so that the driver can check a wide range including the road surface in the vicinity of the host vehicle when the host vehicle is traveling backward. A video P1 in a relatively wide range (for example, a horizontal angle of view of about 120 degrees) is extracted as a display video from the video P in a predetermined area behind the host vehicle photographed by the camera 1. On the other hand, if the host vehicle is traveling forward, the display image extraction unit 12 extracts the image P2 in a narrower range as the display image than when traveling backward. This is because, when an image of a very wide range is displayed on the display 2 while traveling forward, for example, when the subsequent vehicle is displayed as an image, the appearance of the subsequent vehicle is reflected in the rearview mirror. This is because the driver may misunderstand that the following vehicle exists far from the actual position. In order to avoid this, when the host vehicle is traveling forward, the display image extraction unit 12 narrows the angle of view of the image displayed on the display 2 to, for example, about 30 degrees to bring it closer to the mirror reflection image of the room mirror. I am doing so. Note that the angle of view of the image displayed on the display 2 when the host vehicle is traveling forward may be set to an optimum angle of view according to the size of the room mirror, the size of the display 2, and the like.

  The video output unit 13 includes an output buffer corresponding to the frame size of the display video displayed on the display 2. The display video data extracted by the display video extraction unit 12 is stored in this output buffer. The video output unit 13 outputs the display video data stored in the output buffer to the display 2 as needed. Thus, if the host vehicle is traveling backward, for example, as shown in FIG. 4A, an image of a relatively wide area behind the host vehicle is displayed on the display 2, and if the host vehicle is traveling forward. For example, as shown in FIG. 4B, an image of a relatively narrow area behind the host vehicle is enlarged to an image size equivalent to the mirror reflection image of the rearview mirror and displayed on the display 2.

  As described above, in the vehicular rear monitoring apparatus of the present embodiment, if the host vehicle is traveling forward, the image of a relatively narrow area behind the host vehicle is enlarged to a video size equivalent to the reflection image of the room mirror. For example, when confirming, for example, a subsequent vehicle following the host vehicle on the display image of the display 2, the distance and speed feeling with the subsequent vehicle are correctly displayed to the driver of the host vehicle. It can be grasped. On the other hand, as the angle of view of the display image displayed on the display 2 becomes narrower while the host vehicle is traveling forward, there is a blind spot area behind the host vehicle that is captured by the rear camera 1 but not displayed as an image. For example, if an obstacle such as a two-wheeled vehicle trying to pass the host vehicle enters this blind spot area, the driver of the host vehicle cannot recognize that the obstacle exists. . Therefore, in the vehicle rear monitoring apparatus according to the present embodiment, the image processing unit 10 is provided with the obstacle detection unit 14 and the obstacle notification unit 15, and images that are not displayed on the display 2 among the captured images of the rear camera 1 are used. An obstacle behind the host vehicle is detected, and if there is an obstacle, the driver of the host vehicle is notified accordingly.

  The visual field range that can be confirmed when a rearview mirror attached to a general passenger car is viewed from the driver's seat is substantially the same as the visual field range captured by a camera with an angle of view of 30 degrees attached to the rear of the vehicle. Of course, the corresponding camera angle of view varies somewhat depending on factors such as the curvature of the rearview mirror, the size of the rear glass, the thickness of the rear pillar, the rearview mirror and the driver's seat eye point, and the distance to the rear glass. Here, a camera with an angle of view of 30 degrees attached to the center of the rear of the vehicle having a vehicle width of 1.8 m has a blind spot of a triangular area of 3.4 m in length and 0.9 m in width when projected onto the road surface. In addition, since the part exceeding a vehicle width can be confirmed using a door mirror etc., it is not set as the blind spot here.

  In the vehicle rear monitoring apparatus according to the present embodiment, as described above, the rear camera 1 that is a wide-angle camera captures an image of a wide area behind the vehicle. Since an image close to a mirror reflection image is displayed on the display 2, when the host vehicle is traveling forward, a blind spot area equivalent to that when displaying an image captured by a camera with an angle of view of 30 degrees is provided. Occur. Since this blind spot area is large enough for an obstacle such as a two-wheeled vehicle to pass the host vehicle from behind the host vehicle, the image processing unit 10 is used in the vehicle rear monitoring apparatus of the present embodiment. The obstacle detection unit 14 determines the presence / absence of an obstacle in the blind spot area, and when it is determined that an obstacle exists, the obstacle notification unit 15 notifies the driver of the vehicle to that effect.

  Hereinafter, specific examples of processing by the obstacle detection unit 14 and the obstacle notification unit 15 will be described in more detail. In the following, a specific example of processing by the obstacle detection unit 14 and the obstacle notification unit 15 will be described on the assumption that the host vehicle is traveling forward. However, the host vehicle is displayed on the display 2 while the host vehicle is traveling backward. If the rear camera 1 captures an image of an area wider than the image range, the obstacle detection unit 14 and the obstacle notification unit 15 perform the same processing even when the host vehicle is traveling backward, It is also possible for the driver of the host vehicle to recognize that an obstacle exists behind the host vehicle.

  The obstacle detection unit 14 is an image of the rear of the host vehicle that is not displayed on the display 2 among the images of the predetermined area behind the host vehicle captured by the rear camera 1, that is, the video stored in the input buffer of the video input unit 11. Among them, an obstacle behind the host vehicle is detected using an image that is not extracted as a display image by the display image extracting unit 12. Specifically, the obstacle detection unit 14 sets, for example, a part of the area behind the host vehicle that is not displayed on the display 2 with the road surface as the monitor area. Then, an obstacle such as a two-wheeled vehicle approaching the rear of the host vehicle is detected based on the change in the luminance pattern of the video in the monitor area.

  In this case, as shown in FIG. 5, the obstacle detection unit 14 can identify an obstacle approaching the host vehicle and an object moving away from the host vehicle such as a white line or a manhole on the road surface. It is desirable to set the monitor areas at two or more positions having different distances from each other. In the example shown in FIG. 5, an image range that reflects a rectangular area of 1 m in width and 0.5 m in height on the road surface 1.5 m away from the rear end of the host vehicle is set as the first monitor region M1, and 2 An image range in which a rectangular area of 1 m in width and 0.5 m in length on a road surface separated by 0.5 m is set as the second monitor area M2. In addition, it is desirable that the distance from the host vehicle in the rectangular regions serving as the monitor regions M1 and M2 is appropriately changed according to the traveling speed of the host vehicle. For example, since it is assumed that an obstacle such as a two-wheeled vehicle that follows is closer to the host vehicle during low-speed traveling than that during high-speed traveling, the monitor region M1 is displayed when the traveling speed of the host vehicle decreases. , M2 is changed to a position close to the host vehicle. Further, the monitor areas M1 and M2 are areas with the background of the road behind the host vehicle that is not displayed on the display 2 as a background. For example, the monitor areas M1 and M2 are displayed on the display 2 as the traveling direction (forward, backward) of the host vehicle changes. When the displayed video range is changed, or when the video range displayed on the display 2 is changed according to the operation input by the driver of the host vehicle using the operation input device 7, the monitor areas M1 and M2 are obtained. The position of the rectangular area is appropriately changed according to the video range of the display video after the change.

  The monitor areas M1 and M2 set as described above basically reflect the road surface when there is no obstacle behind the host vehicle. The obstacle detection unit 14 captures video for each of the monitor areas M1 and M2 for each frame of the captured video of the rear camera 1, that is, each time a new captured video of the rear camera 1 is stored in the video input unit 11. The luminance pattern (luminance value distribution and luminance value variance) is calculated. In addition, the obstacle detection unit 14 calculates the time average over the past predetermined time of the luminance patterns of the monitor areas M1 and M2. The time average of the luminance pattern is used as a reference value for detection logic described later. When the road surface type changes, it is expected that the road surface state will change and the average luminance and luminance variance of the road surface will change. Therefore, the obstacle detection unit 14 uses the information from the road information acquisition device 6. When it is detected that the road type has changed, it is desirable to clear the time average (reference value) of the luminance value pattern so far and newly calculate the time average (reference value) of the luminance pattern. .

  The obstacle detection unit 14 compares the luminance pattern of each of the monitor areas M1 and M2 obtained for each frame of the captured video of the rear camera 1 with a reference value to determine whether there is an obstacle behind the host vehicle. judge. Here, when there is no obstacle behind the host vehicle and there are no objects such as white lines or manholes on the road surface, both the first monitor area M1 and the second monitor area M2 have road surfaces of a certain color. Since the image is projected, the luminance dispersion value becomes a small value. Therefore, the obstacle detection unit 14 has an obstacle behind the host vehicle while both the luminance dispersion value of the first monitor area M1 and the luminance dispersion value of the second monitor area M2 are kept small. Judge that not.

  In addition, when there is an object such as a white line or manhole on the road surface, or shadows such as viaducts are reflected on the road surface, when the vehicle travels on the road surface, the color of the road surface behind the vehicle temporarily changes. Change. In this case, first, the luminance pattern of the first monitor region M1 close to the host vehicle changes greatly from the reference value, and then the luminance pattern of the second monitor region M2 changes greatly from the reference value. Therefore, when the brightness pattern of the second monitor area M2 changes greatly after the brightness pattern of the first monitor area M1 changes significantly, the obstacle detection unit 14 changes the brightness pattern of each of the monitor areas M1 and M2. Is determined to be due to a temporary change in the color of the road surface, and it is determined that there is no obstacle behind the host vehicle. In addition, when the color of the road surface behind the host vehicle changes temporarily due to the influence of shadows such as white lines on the road surface, manholes, and viaducts, the timing at which the luminance patterns of the monitor areas M1 and M2 change greatly is the driving of the host vehicle. Since there is a correlation with the speed, when the timing from when the luminance pattern of the first monitor area M1 changes greatly to when the luminance pattern of the second monitor area M2 changes greatly is correlated with the traveling speed of the host vehicle, It may be determined that the change in the luminance pattern of each of the monitor areas M1 and M2 is due to a temporary change in the color of the road surface, and it is determined that there is no obstacle behind the host vehicle.

  On the other hand, when there is an obstacle such as a two-wheeled vehicle approaching the host vehicle from behind, the luminance pattern of the second monitor region M2 is first displayed before a large change appears in the luminance pattern of the first monitor region M1. It varies greatly from the reference value. Thereafter, when the obstacle further approaches the rear of the host vehicle, the luminance pattern of the first monitor region M1 greatly changes from the reference value. Therefore, the obstacle detection unit 14 determines that there is an obstacle such as a two-wheeled vehicle behind the host vehicle when the luminance pattern of the second monitor region M2 changes greatly before the luminance pattern of the first monitor region M1 changes significantly. judge.

  By the way, depending on the direction of solar radiation, the shadow of the host vehicle may be reflected on the road surface behind the host vehicle, and the shadow of the host vehicle may have an adverse effect on the obstacle detection process as described above. Here, when the shadow of the own vehicle is uniformly reflected over the entire area of the first monitor area M1 or the entire area of the second monitor area M2, the time average of the luminance pattern serving as the reference value is the shadow of the own vehicle. However, if the boundary of the shadow of the own vehicle is located in the first monitor area M1 or the second monitor area M2, the influence of the shadow of the own vehicle appears on the luminance distribution and the obstacle It is thought to have an adverse effect on the object detection process. Therefore, the obstacle detection unit 14 determines whether or not the shadow boundary of the own vehicle is located in the monitor areas M1 and M2, and if the shadow boundary of the own vehicle is located, the monitor area It is desirable to change the position.

  FIG. 6 shows an example in which the boundary of the shadow S of the host vehicle is located in the second monitor region M2. In the example shown in FIG. 6, two peaks appear in the luminance value distribution of the second monitor region M2 due to the influence of the shadow S of the host vehicle. When two peaks appear in the luminance value distribution in the monitor area in this way, the obstacle detection unit 14 determines that the shadow boundary of the own vehicle exists in the monitor area, and determines the position of the monitor area. change. When the position is changed and the peak of the luminance value distribution in the monitor area becomes one, thereafter, the obstacle detection process described above is performed using the monitor area at the position.

  In the example shown in FIG. 6, since two peaks appear in the luminance value distribution of the second monitor area M2, as shown in FIG. 7, the position of the second monitor area M2 is shifted in a direction away from the host vehicle, for example. Alternatively, the second monitor area M2 is narrowed. Then, when the luminance value distribution (histogram) in the second monitor region M2 is observed at that position and one peak is obtained, the position is reset as the second monitor region M2. If the peak does not become one even if the second monitor area M2 is moved from the original position to the extent that there is no overlapping area, the two peaks appearing in the luminance value distribution are influenced by the shadow S of the host vehicle. The obstacle detection unit 14 determines that there is an obstacle in the vicinity of the second monitor region M2, because it is considered that the obstacle is behind the vehicle.

  When an obstacle behind the host vehicle is detected by the obstacle detection unit 14, an obstacle detection signal is sent from the obstacle detection unit 14 to the obstacle notification unit 15. When an obstacle detection signal is sent from the obstacle detection unit 14, the obstacle notification unit 15 performs a process of notifying the driver of the host vehicle that an obstacle exists behind the host vehicle. Specifically, when the obstacle detection unit 14 detects an obstacle behind the host vehicle, the obstacle notification unit 15 displays, for example, characters or characters on the display video stored in the output buffer of the video output unit 13. A warning by a graphic or the like is superimposed and displayed on the display 2 and a warning sound is output from the speaker 3 to notify the driver of the host vehicle that there is an obstacle behind the host vehicle. In addition, the obstacle notification 15 is an image of a video that is not extracted as a display video out of the video captured by the rear camera 1 stored in the video input unit 11 instead of superimposing a warning by characters, graphics, or the like on the display video. Among them, a video portion corresponding to the obstacle detected by the obstacle detection unit 14 may be cut out and superimposed on the display video. Further, when an obstacle behind the host vehicle is detected by the obstacle detection unit 14, for example, the video range extracted as the display video by the display video extraction unit 12 is expanded to a range where the obstacle is reflected, It is also effective to display an image on the display 2.

  Here, it is desirable to change the frequency of notification to the driver of the host vehicle by the obstacle notification unit 15 according to the traveling speed of the host vehicle. That is, since the degree of difficulty in driving due to the fact that an obstacle such as a two-wheeled vehicle is approaching the rear of the host vehicle is greater during high speed traveling than when traveling at low speed, the obstacle notifying unit 15 It is more effective to increase the frequency of notification to the driver of the host vehicle as the speed is higher. When the host vehicle is stopped, it is assumed that the change in the luminance value of the image due to the change in the surrounding environment is large. Therefore, the notification to the driver by the obstacle notification unit 15 is stopped or the obstacle detection is performed. It is desirable to stop the obstacle detection process itself by the unit 14.

  As described above in detail with reference to specific examples, the vehicle rear monitoring apparatus according to the present embodiment is relatively based on an image behind the host vehicle captured by the rear camera 1 while the host vehicle is traveling forward. A video of a narrow area is extracted as a display video, and this display video is enlarged to be equivalent to a room mirror and displayed on the display 2, and based on a video that is captured by the rear camera 1 but is not displayed on the display 2, A process of detecting an obstacle behind the host vehicle is performed, and when an obstacle part behind the host vehicle is detected, the driver of the host vehicle is notified accordingly. Therefore, according to the vehicle rear monitoring device, while the host vehicle is traveling forward, the driver of the host vehicle can display the rear image of the host vehicle so that the driver can correctly grasp the sense of distance and speed. If there is an obstacle, the driver of the host vehicle can surely recognize the presence of the obstacle.

  The vehicle rear monitoring apparatus described above is an example of an application of the present invention, and is not intended to limit the technical scope of the present invention to the contents described in the above embodiments. Absent. That is, the technical scope of the present invention is not limited to the specific technical matters disclosed in the above embodiments, but includes various modifications, changes, alternative techniques, and the like that can be easily derived from this disclosure. For example, in the vehicle rear monitoring apparatus described above, a monitor area is set for a part of an image captured by the rear camera 1 but not displayed on the display 2, and a change in the luminance pattern of the image in the monitor area is performed. For example, an image processing such as pattern matching or edge detection is performed on an image captured by the rear camera 1 but not displayed on the display 2, for example, An obstacle behind the host vehicle may be detected.

It is a block diagram which shows the structure of the vehicle rear monitoring apparatus to which this invention is applied. It is a functional block diagram which shows the function structure of a video processing unit. It is a figure which shows the relationship between the picked-up image of a rear camera, and the display image displayed on a display. It is a figure which shows an example of the display image displayed on a display, (a) is an example of the display image displayed on a display when the own vehicle is traveling backward, (b) is displayed on the display while the own vehicle is traveling forward. It is an example of the display image displayed. It is a figure explaining the example of the process which detects the obstruction behind the own vehicle, and is a figure which shows a mode that the monitor area | region was set to the video range not displayed on a display. It is a figure which shows the example in case the boundary of the shadow of the own vehicle is located in a monitor area | region. It is a figure which shows a mode that the position of the monitor area | region was changed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rear camera 2 Display 3 Speaker 10 Video processing unit 11 Video input part 12 Display video extraction part 13 Video output part 14 Obstacle detection part 15 Obstacle notification part P Rear camera image | video P1 Display image at the time of reverse travel P2 Forward travel Display image at the time M1 1st monitor area M2 2nd monitor area

Claims (11)

Imaging means for imaging an image of a predetermined area behind the vehicle;
Display video extraction means for extracting, as a display object, a video of a first area when the vehicle is moving backward, and a video of a second area that is narrower than the first area when the vehicle moves forward, among the videos captured by the imaging means; ,
Display means for displaying the video extracted as a display target by the display video extraction means;
Obstacle detection means for detecting an obstacle behind the vehicle based on a change in luminance pattern of a video that is not extracted as a display target by the display video extraction means when the vehicle moves forward among images captured by the imaging means ,
A vehicle rear monitoring device, comprising: an informing means for informing the vehicle occupant of the presence of an obstacle when the obstacle detecting means detects an obstacle behind the vehicle.   The obstacle detection means sets, as a monitor area, a part of the image captured by the photographing means with the road surface behind the vehicle not displayed on the display means as a background, and a luminance pattern of the image in the monitor area The vehicle rear monitoring apparatus according to claim 1, wherein an obstacle behind the vehicle is detected based on the change of the vehicle.   The obstacle detection means obtains an average of the luminance pattern of the monitor area over a past predetermined time as a reference value, compares the current luminance pattern of the monitor area with the reference value, and detects an obstacle behind the vehicle. The vehicle rear monitoring device according to claim 2, wherein the vehicle rear monitoring device is detected.   The vehicular rear monitoring apparatus according to claim 3, wherein the obstacle detection unit newly calculates the reference value every time a change in road type is detected.   The obstacle detection means sets the monitor areas at a plurality of positions at different distances from the vehicle, and the obstacles behind the vehicle are applied to the vehicle based on the order in which the luminance patterns of the plurality of monitor areas change. The vehicle rear monitoring apparatus according to any one of claims 2 to 4, wherein it is determined whether or not the obstacle is approaching.   The obstacle detection means determines that a change in the color of the road surface is detected when a timing at which a luminance pattern of the plurality of monitor areas changes correlates with a traveling speed of the vehicle. Item 6. The vehicle rear monitoring apparatus according to Item 5.   The vehicle rear monitoring according to any one of claims 2 to 6, wherein the obstacle detection means changes the position of the monitor area when the area to be displayed is changed. apparatus.   The obstacle detection means determines whether or not the vehicle shadow boundary is located in the monitor area based on the luminance pattern of the monitor area, and when the vehicle shadow boundary is located The vehicle rear monitoring device according to any one of claims 2 to 7, wherein the position of the monitor region is changed.   The vehicular rear monitoring apparatus according to any one of claims 1 to 8, wherein the notification unit changes a frequency of notifying a vehicle occupant of the presence of an obstacle according to a traveling speed of the vehicle.   The vehicle rear monitoring apparatus according to claim 9, wherein the notification unit increases the frequency of notifying the vehicle occupant of the presence of an obstacle as the traveling speed of the vehicle increases. Imaging a predetermined region of the vehicle rear by the imaging means, of the image that the imaging means has captured, and displays on the display means extracts the image of the area smaller than when the vehicle backward for display at the time of forward traveling of the vehicle, the display Vehicle rear monitoring characterized in that an obstacle behind the vehicle is detected based on a change in luminance pattern of an image that is not extracted as a target and is not displayed on the display means, and the presence of the obstacle is notified to the vehicle occupant. Method.

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