Abstract:
A rear lamp (RL) provided on a rear part of a vehicle (CAR 1 ), wherein the rear lamp (RL) includes, in addition to a normal lamp, a sub-tail lamp (STL) configured to be lit on at least when a following vehicle is self-driving and to be detectable by the following vehicle when lit on. Since the following vehicle detects the sub-tail lamp (STL) lit in addition to the normal lamp, it is possible to detect the sub-tail lamp (STL) more accurately and more reliably than in detection of the normal lamp, and to detect the preceding vehicle (CAR 1 ) in a highly accurate and quick manner.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a rear lamp which is capable of assisting self-driving, and particularly, to a rear lamp which enables a following vehicle to detect an own vehicle as a preceding vehicle precisely and rapidly. 
       BACKGROUND ART 
       [0002]    There are self-driving techniques for detecting a white line (lane) which is drawn on a road in front of a vehicle or a preceding vehicle in front of the vehicle and controlling the driving direction of the own vehicle based on the detected results. Patent Document 1 has proposed techniques for taking an image of a front area of a vehicle and detecting a white line and a preceding vehicle from the image to control self-driving. Furthermore, as techniques for detecting a preceding vehicle in a taken image, Patent Document 2 has proposed techniques for detecting a preceding vehicle by detecting tail lamps of the preceding vehicle from bright points in the taken image. 
       PRIOR ART DOCUMENT 
     Patent Document 
       [0003]    Patent Document L: JP-A-2014-51241 
         [0004]    Patent Document 2: JP-A-2009-227088 
       SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
       [0005]    In the techniques for detecting a preceding vehicle from bright points in a taken image as in Patent Document 2, it is difficult to detect the preceding vehicle precisely. That is, when a front of the vehicle is imaged, various bright points of sign lamps at roads, lamps of buildings, head lamps of oncoming vehicles and the like are often taken in the image. It is difficult to distinguish the bright points of the tail lamps of the preceding vehicle from those bright points. Therefore, when performing self-driving control by detecting a preceding vehicle, it becomes difficult to control self-driving precisely. 
         [0006]    Conventionally, the bright points in the image are detected to be bright points of the tail lamps of the preceding vehicle by verifying following attributes: the bright points of the left and right rear lamps, particularly of the tail lamps, of the preceding vehicle are imaged in a pair in a horizontal direction; the brightness (luminance) of the bright points of the left and right tail lamps are the same; the positions of the bright points of the left and right tail lamps vary together in the image; and the bright points of the tail lamps of the preceding vehicle are red. However, when a plurality of preceding vehicles are present in front of the vehicle, it is difficult to verify the above attributes since the tail lamps of these preceding vehicles are detected as a whole, and therefore, the precise detection of the preceding vehicle is obstructed. Furthermore, it takes time in detecting the preceding vehicles, so that responsiveness is poor when following the preceding vehicle, which night interfere the self-driving. 
         [0007]    An object of the present invention is to provide a rear lamp which enables a following vehicle which drives to follow a preceding vehicle to detect the preceding vehicle precisely and rapidly and to assist self-driving of the following vehicle. 
       Means for Solving the Problem 
       [0008]    The present invention provides a rear lamp disposed at a rear of a vehicle, which includes a sub-lamp in addition to a normal lamp, wherein the sub-lamp is configured to be lit on at least when a following vehicle is self-driving and the lighting is detectable by the following vehicle. 
         [0009]    The sub-lamp of the present invention may be configured to emit near-infrared light. In addition, the sub-lamp may be configured integrally with or separately from rear lamps which are installed in the vehicle. Furthermore, the sub-lamp is lit on when the vehicle is self-driving or the following vehicle is judged to be self-driving. 
       Effect of the Invention 
       [0010]    According to the present invention, the following vehicle can detect the preceding vehicle by detecting the sub-lamp in addition to the normal lamp. Since the detection of the sub-lamp can be more accurate and reliable comparing with the detection of the normal lamp, the preceding vehicle can be detected precisely and rapidly. Particularly, the sub-lamp of the preceding vehicle can be detected accurately by lighting on the sub-lamp to emit near-infrared light. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0011]      FIG. 1  is a schematic diagram illustrating self-driving. 
           [0012]      FIG. 2A  is a rear view of an automobile (preceding vehicle) including a rear lamp of a first embodiment. 
           [0013]      FIG. 2B  shows a partial section of the front view of the rear lamp. 
           [0014]      FIG. 3A  is a block diagram of a preceding-vehicle detecting device for a following vehicle. 
           [0015]      FIG. 3B  is a pixel arrangement diagram of an imaging element. 
           [0016]      FIG. 4A  shows spectral characteristics in the preceding-vehicle detecting device. 
           [0017]      FIG. 4B  shows spectral characteristics in the preceding-vehicle detecting device. 
           [0018]      FIG. 4C  shows spectral characteristics in the preceding-vehicle detecting device. 
           [0019]      FIG. 5A  is an image for detecting a preceding vehicle which is taken by a following vehicle. 
           [0020]      FIG. 5B  is an image for detecting a preceding vehicle which is taken by a following vehicle. 
           [0021]      FIG. 5C  is an image for detecting a preceding vehicle which is taken by a following vehicle. 
           [0022]      FIG. 6  is a rear view of an automobile (preceding vehicle) including a rear lamp of a second embodiment. 
           [0023]      FIG. 7A  is a rear view of an automobile (preceding vehicle) including a rear lamp of a third embodiment. 
           [0024]      FIG. 7B  shows a partial section of the perspective view of a sub-center lamp. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0025]    Hereinafter, embodiments of the present invention will be described with reference to the drawings.  FIG. 1  is a schematic diagram illustrating self-driving using a vehicle rear lamp according to the present invention. When an automobile CAR 1  is self-driving on a road, or an automobile CAR 1  is normal-driving (not self-driving) on a road and detects that a following vehicle CAR 2  is following, rear lamps RL of the preceding vehicle CAR 1  are set to a self-driving lighting mode. The self-driving lighting mode is automatically set when the preceding vehicle CAR 1  is self-driving, while the self-driving lighting mode is set via a judgment by a driver in the preceding vehicle CAR 1  when the preceding vehicle CAR 1  is normal-driving. In this way, when the preceding vehicle CAR 1  and the following vehicle CAR 2  are present and the preceding vehicle CAR 1  is set to the self-driving lighting mode, the rear lamps RL of the preceding vehicle CAR 1  are lit on differently from the normal-driving lighting mode. 
         [0026]    The following vehicle CAR 2  under self-driving takes an image of a front area by an imaging device CAM installed in the own vehicle and detects the preceding vehicle CAR 1  based on the image. Detecting the preceding vehicle CAR 1  is performed based on the bright points of the rear lamps RLs of the preceding vehicle CAR 1  appearing in the image. In the present invention, when the rear lamps RL of the preceding vehicle CAR 1  are set to the self-driving lighting mode, the following vehicle CAR 2  detects a unique bright point in the image, and thus, the following vehicle CAR 2  can detect the preceding vehicle CAR 1  based on the bright point. When the preceding vehicle CAR 1  is detected, the following vehicle CAR 2  is set to self-driving to follow the detected preceding vehicle CAR 1 . Description of self-driving in detail is omitted herein. 
       First Embodiment 
       [0027]      FIG. 2A  is a rear view of a preceding vehicle CAR 1 , i.e., an automobile, including rear lamps according to a first embodiment of the present invention. Rear lamps RLs are disposed respectively in the left and right of the rear of the body panel of the automobile CAR 1 . Each rear lamp RL is configured as a rear combination lamp of which a tail and stop lamp T&amp;SL, a backup lamp BUL and a turn signal lamp TSL are incorporated integrally in a lamp housing  1 . Since those lamps T&amp;SL, BUL, TSL simply use existing rear lamps which are normally lit on as rear lamps, detailed description thereof is omitted herein. 
         [0028]      FIG. 2B  shows a partial section of the front view of a left rear lamp RL as seen from the rear of the automobile. Although not shown in the drawings, a right rear lamp has a similar structure and is symmetric with the left rear lamp RL. The lamp housing  1  of the rear lamps RLs includes a lamp base  11  and a transparent front cover  12  attached to the front of the lamp base  11 . The interior of the lamp base  11  is divided into a plurality of areas. Light sources are respectively disposed in each of the divided areas to form the lamps T&amp;SL, BUL, TSL. 
         [0029]    The tail and stop lamp T&amp;SL is configured as a plurality of red LEDs (semiconductor light-emitting elements)  13  as light sources disposed inside the lamp base  11 . The red LEDs  13  emit light with low brightness as tail lamp and emit light with high brightness as stop lamp. Furthermore, the sub-tail lamp STL is provided integrally with the tail and stop lamp T&amp;SL which is installed in the automobile in the first embodiment. 
         [0030]    As shown in  FIG. 2B , the sub-tail lamp STL uses a plurality of near-infrared LEDs  14  as light sources. The near-infrared LEDs  14  together with the red LEDs  13  of the tail and stop lamp T&amp;SL is disposed in the divided areas of the lamp base  11 . The near-infrared LEDs  14  are controlled to be lit on independently from the red LEDs  13 . The near-infrared LEDs  14  are lit on when set in the self-driving lighting mode. 
         [0031]      FIG. 3A  is a schematic diagram of a preceding-vehicle detecting device  2  provided in the following vehicle CAR 2 . The imaging device CAM shown in  FIG. 1  includes an imaging optical system  21  and an imaging element  22 . The imaging device CAM takes an image of the front area of the vehicle. The imaging device CAM is connected to a signal processing unit  23  which processes the obtained imaging signal and obtains the image and is further connected to a vehicle detecting unit  24  which detects the preceding vehicle by analyzing the obtained image. 
         [0032]    The imaging element  22  is configured by arranging semiconductor light receiving elements in a matrix form, such as CCD, CMOS. As shown in  FIG. 3B , the imaging element  22  is composed of CMOS imaging elements obtained by replacing one pixel B (blue) among pixels B (blue), G (green), and R (red) which form a Bayer Array with an pixel IR (near-infrared). Therefore, as shown in  FIG. 4A , the imaging element  22  has a light receiving sensitivity of receiving light having light regions of B, G, R and IR. Particularly, as shown in  FIG. 4B , the light receiving sensitivities of R and IR correspond to spectroscopic luminosities of the red LEDs  13  and the near-infrared LEDs  14 . 
         [0033]    The vehicle detecting unit  24  detects the preceding vehicle CAR 1  by detecting the bright points in the image, i.e., the bright points of the rear lamps RLs of the preceding vehicle CAR 1 . Therefore, the vehicle detecting unit  24  detects the bright points of the rear lamps RLs having light from the visible region to the near-infrared region when all signals of pixels B, G, R, and IR processed by the signal processing unit  23  are selected. As shown in  FIG. 4C , the vehicle detecting unit  24  only detects the light emitted by the near-infrared LEDs  14 , i.e., the bright points of the sub-tail lamp STL, when only the signal of the pixel IR is selected. 
         [0034]    Although description is omitted herein, a self-driving system provided in the following vehicle CAR 2  controls the speed and steering of the vehicle to follow the preceding vehicle CAR 1  detected by the vehicle detecting unit  24 , thereby performing self-driving. 
         [0035]    In the case shown in  FIG. 1 , the preceding vehicle CAR 1  is not set to the self-driving lighting mode when the preceding vehicle CAR 1  is normal driving, or a driver of the preceding vehicle CAR 1  judges that the following vehicle CAR 2  is not self-driving. Therefore, the rear lamps RL of the preceding vehicle CAR 1  are set in the normal lighting mode. The rear lamps RL of the preceding vehicle CAR 1  are automatically set to the self-driving lighting mode when the preceding vehicle CAR 1  is self-driving. Alternatively, even if the preceding vehicle CAR 1  is normal driving, the rear lamps RL thereof are manually set to the self-driving lighting mode when the driver of the preceding vehicle CAR 1  judges that the following vehicle CAR 2  is self-driving. 
         [0036]    The sub-tail lamps STL are lit on when the tail and stop lamps T&amp;SL of the rear lamps RL are lit on when the self-driving lighting mode is set. That is, the visible light of the red LEDs  13  is emitted from the preceding vehicle CAR 1 , and the near-infrared light of the near-infrared LEDs  14  of the sub-tail lamps STL is emitted from the preceding vehicle CAR 1  at the same time when the tail and stop lamps T&amp;SL are lit on as the tail lamps. At this time, since the near-infrared light emitted from the sub-tail lamps STL is invisible for the driver in the following vehicle CAR 2 , it will not cause the driver to misunderstand that the stop lamps of the preceding vehicle CAR 1  are lit on. 
         [0037]    The imaging device CAM of the preceding-vehicle detecting device  2  of the following vehicle CAR 2  takes an image of the front area of the vehicle when the following vehicle CAR 2  is self-driving. As shown in  FIG. 5A , the rear lamps RL of the preceding vehicle CAR 1  are taken in the image. Then, the vehicle detecting unit  24  detects the bright points of the rear lamps RL of the preceding vehicle CAR 1  from the taken image. In this case, the vehicle detecting unit  24  selects signals of all pixels B, G, R, and IR of the imaging element  22  as a first detection or selects only the signal of the pixel R, thereby detecting the bright points of the red LEDs  13  as shown in  FIG. 4B . 
         [0038]    In the first detection, the vehicle detecting unit  24  detects the preceding vehicle CAR 1  based on a pair of bright points in visible region appearing in the image. That is, as shown in  FIG. 5B , the left and right rear lamps RL of the preceding vehicle CAR 1  are imaged as a pair of bright points (black parts in the figure) aligned at a predetermined interval at left and right in the image during the first detection. The pair of bright points moves synchronously with the movement of the preceding vehicle CAR 1 . Thus, the vehicle detecting unit  24  can detect the preceding vehicle CAR 1  by detecting a pair of bright points with such behavior. 
         [0039]    However, the image also contains the bright points of head lamps of an oncoming vehicle CAR 3  and the bright points of road sign lamps and street lamps SL. It is difficult to only detect the bright points of the rear lamps RL of the preceding vehicle CAR 1  as all the bright points are mixed. The vehicle detecting unit  24  will only select the signal of the pixel IR of the imaging element  22  and detect the bright points of the near-infrared LEDs  14 , which is shown in  FIG. 4B , as a second detection if the preceding vehicle CAR 1  cannot be properly detected by the vehicle detecting unit  24  due to the above reason. 
         [0040]    As shown in  FIG. 5C , the bright points of the visible light are removed and only the bright points of the near-infrared light are left in the image during the second detection. That is, only the bright points of the light emitted by each near-infrared LED  14  of the sub-stop lamps STL which are respectively at the left and right rear lamps RL of the preceding vehicle CAR 1  are imaged. 
         [0041]    In this image, the left and right sub-tail lamps STL of the preceding vehicle CAR 1  are taken as a pair of bright points aligned at a predetermined interval in the left and right, the same as in the first detection, so that the vehicle detecting unit  24  can detect the preceding vehicle CAR 1  by detecting the pair of bright points. Although road sign lamps and street lamps SL may emit near-infrared light, the amount thereof is extremely small comparing to the visible light even if the bright points of the near-infrared light are taken in the image. 
         [0042]    Therefore, comparing to the first detection, the bright points for the vehicle detecting unit  24  as the detection objects in the second detection is extremely less, and those are less mixed, so that the preceding vehicle CAR 1  can be detected precisely and rapidly. In this way, an appropriate self-driving is assisted by detecting the preceding vehicle CAR 1  precisely and rapidly, particularly in a case where the following self-driving vehicle CAR 2  follows the preceding vehicle CAR 1 , Incidentally, the second detection may be performed without the first detection, and thus, the preceding vehicle CAR 1  can be detected more rapidly. 
       Second Embodiment 
       [0043]      FIG. 6  is a rear view of an automobile including a rear lamp of a second embodiment of the present invention. In the second embodiment, sub-rear lamps SRL, which are independent from left and right rear lamps RL, are disposed at the rear of the preceding vehicle CAR 1 . That is, the rear lamps RL are disposed respectively at the left and right of the rear of the body panel of the automobile CAR 1 . The rear lamps RL have the same structure as that of the existing rear lamps. Furthermore, the sub-rear lamps SRL, which are independent from the installed rear lamps RLs, are disposed respectively at the left and right of an upper portion of the rear of the body panel. The sub-rear lamps SRL are located in left and right pillars near the roof panel. The sub-rear lamps SRL are configured as a lamp in which near-infrared LEDs are mounted in the lamp housing as light sources (not shown). The near-infrared LEDs of the sub-rear lamps SRL, which are independent from the rear lamps RL, are lit on when set to the self-driving lighting mode. 
         [0044]    According to the second embodiment, the vehicle detecting unit  24  of the preceding-vehicle detecting unit  2  of the following vehicle CAR 2  constantly detects signals of all pixels, i.e., pixels B, G, R and IR, of the imaging element  22  of the imaging device CAM. Therefore, the vehicle detecting unit  24  detects a left-right pair of bright points of the visible light of the left and right rear lamps RL of the preceding vehicle CAR and a left-right pair of bright points of the near-infrared light of the left and right sub-rear lamps SRL of the preceding vehicle CAR 1  at the same time. 
         [0045]    In the second embodiment, the preceding vehicle CAR 1  lights on the left and right rear lamps RL without lighting the sub-rear lamps SRL when normal driving. The preceding vehicle CAR 1  lights on the left and right rear lamps RL and the left and right sub-rear lamps SRL at the same time in the self-driving lighting mode. Since the light of the left and right sub-rear lamps SRL are invisible, it will not cause the driver of the following vehicle CAR 2  to misunderstand that stop lamps of the preceding vehicle CAR 1  are lit on. 
         [0046]    The left-right pair of bright points of the visible light of the rear lamps RL and the left-right pair of bright points of the near-infrared light of the sub-rear lamps SRL are obtained in the image simultaneously when the rear lamps RL and the sub-rear lamps SRL of the preceding vehicle CAR 1  are in the self-driving lighting mode and an image is taken in the following vehicle CAR 2 . Thus, the vehicle detecting unit  24  detects the two pairs of bright points. Since the two pairs of bright points, i.e., four bright points, move synchronously with the preceding vehicle CAR 1 , the vehicle detecting unit  24  can detect the preceding vehicle precisely and rapidly by detecting the two pairs of synchronously moving bright points. 
       Third Embodiment 
       [0047]      FIG. 7A  is a rear view of an automobile including a rear lamp of a third embodiment of the present invention. In center of a rear panel RP of the automobile, i.e., the area between left and right rear lamps RL in the rear of the body panel, a sub-center lamp SCL is disposed independently of the area from installed rear lamps RL. The sub-center lamp SCL includes a front cover which has light absorbing function. 
         [0048]      FIG. 7B  shows a partial section of perspective view of the sub-center lamp SCL, whose lamp housing  1 A includes a lamp base  11  and a front cover  12 . The front cover  12  is made of transparent material. The interior area, excluding the areas having a plurality of dots, is coated with light absorbing material  15  such as carbon black. Therefore, the area coated with carbon black is a light absorbing area  16  and the dotted areas without carbon black are transparent areas  17 . The transparent areas  17  having a plurality of dots are arranged in a matrix form. Incidentally, in  FIG. 7B , three transparent areas  17  are shown in a vertical direction in order to simplify the illustration. More transparent areas are formed in practice. Furthermore, instead of the above structure, a light absorbing plate having a plurality of through holes along the thickness direction may be used, and the light absorbing plate may be adhered to an outer surface or the inner surface of the front cover  12  made of the transparent material. 
         [0049]    Near-infrared LEDs  14 , which are same as those of the first and second embodiments, are disposed to face the transparent areas  17  respectively in the lamp housing  1 A, The near-infrared LEDs are lit on independently from the rear lamps RL when set to a self-driving lighting mode. The light from the near-infrared LEDs  14  passes through the transparent areas  17  of the front cover  12 . Incidentally, the near-infrared LEDs  14  may not necessarily correspond to the transparent areas  17  respectively, and light from one near-infrared LED  14  may pass through a plurality of transparent areas  17 . 
         [0050]    In the third embodiment, the vehicle detecting unit  24  of the preceding vehicle detecting unit  2  of the following vehicle CAR 2  constantly detects signals of all pixels B, G, R and IR of an imaging element  22 . Therefore, the vehicle detecting unit  24  detects a left-right pair of bright points of visible light of the left and right rear lamps RL of the preceding vehicle CAR 1  and a bright point of near-infrared light of a sub-center lamp SCL at the same time. 
         [0051]    In the third embodiment, the preceding vehicle CAR 1  lights on only the rear lamps RL in a normal driving. Both the sub-center lamp SCL and the rear lamps RL are lit on in the self-driving lighting mode. A part of light from the rear lamps RL may be reflected by the surface of the rear panel RP of the automobile when the rear lamps RL are lit on. Particularly, it becomes difficult for the following vehicle CAR 2  to distinguish bright points between the left and right rear lamps RL when the reflected light by the rear panel RP between the rear lamps RL mixed together with the light directly from the left and right rear lamps RL. In contrast, the light of the left and right rear lamps RL is not reflected by the surface of the sub-center lamp SCL since the front cover  12  of the sub-center lamp SCL has a light absorbing function in the third embodiment. Therefore, the light of the left and right rear lamps RL can be distinguished as independent bright points, so that the preceding vehicle CAR 1  can be detected precisely and rapidly. 
         [0052]    In addition, the light patterns in a matrix form are obtained when the near-infrared LEDs  14  of the sub-center lamp SCL emit light respectively through the transparent areas  17  on the front cover  12 . A plurality of bright points of the sub-center lamp SCL arranged in a matrix form are detected between the left and right pair of bright points of the rear lamps RL when the preceding vehicle CAR 1  is imaged by the following vehicle CAR 2 . The light patterns which have the plurality of bright points in a matrix form between the left and right pair of bright points are not present in a normal automobile driving environment. The following vehicle CAR 2  can precisely and rapidly detects the preceding vehicle CAR 1  by detecting the light patterns. The light patterns of the sub-center lamp SCL are formed by near-infrared light and invisible for the driver in the following vehicle CAR 2 , so the driver does not feel uncomfortable and troublesome. 
         [0053]    Incidentally, in the third embodiment, the specific light patterns may be configured by the near-infrared LEDs  14  of the sub-center lamp SCL. That is, the transparent areas  17  form a pattern. Alternatively, any light pattern may be formed by selectively making some of the near-infrared LEDs  14  in a matrix form to emit light. 
         [0054]    The light pattern, as in this case for example, can be configured to make the necessary driving information of the preceding vehicle CAR 1  as a coded light pattern, such as a bar code, a QR code (registered trademark). The following vehicle CAR 2  which images the preceding vehicle CAR 1  detects and decodes the code displayed by the light patterns, so that the driving information of the preceding vehicle CAR 1  can be obtained. Accordingly, the following vehicle CAR 2  can precisely self-drive by obtaining the driving information of the preceding vehicle CAR 1 . 
         [0055]    In the first to third embodiments, the sub-tail lamps, the sub-rear lamps and the sub-center lamp, which function as sub-lamps for detecting the preceding vehicle, are configured as a lamp emitting near-infrared light, so as not to cause misunderstanding or discomfort for the driver of the following vehicle when the driver sees the lighting from the preceding vehicle, as described above. Therefore, the lamps may emit visible light or light including a visible region when the misunderstanding and discomfort of the driver is not considered or do not occur. 
         [0056]    Furthermore, in the first to third embodiments, the optical intensity and polarization of the light of the sub-tail lamps, the sub-rear lamps and the sub-center lamp may be modulated based on the driving information of the preceding vehicle when emitting the near-infrared light. The following vehicle can obtain the driving information of the preceding vehicle by demodulating the modulated near-infrared light, which is useful in assisting self-driving. 
         [0057]    Incidentally, in the embodiments, the signal of a pixel IR is selected in order to split the visible light and the near-infrared light. Alternatively, the receiving region of light receivable by the imaging element  22  may be selected by an optical filter. As shown by the dash dot line in  FIG. 3A , for example, a near-infrared filter  25  which transmits the near-infrared light is provided in the imaging device CAM. The near-infrared filter  25  may advance and retreat in a light receiving path of the imaging element  22  via a filter driving unit  26  which is controlled by a filter controlling unit  27 . Only the bright points of the near-infrared light can be detected when the near-infrared filter  25  advances in the light receiving path. Alternatively, instead of the near-infrared filter, a tuning filter capable of tuning the transparent areas by changing the applied voltage may be used to only detect the bright points of the near-infrared light. 
         [0058]    This application is based on Japanese Patent Application No. 2014-188460 filed on Sep. 17, 2014, the content of which is incorporated herein by reference. 
       INDUSTRY APPLICABILITY 
       [0059]    The present invention can be used as a rear lamp which is effective in assisting self-driving when the following vehicle follows the preceding vehicle.