Abstract:
A lighting device ( 100 ) for a vehicle, capable of more adequately draw the attention of a pedestrian to the fact that the vehicle is approaching the pedestrian. The lighting device ( 100 ) for a vehicle is provided with an object position detecting section ( 110 ) and a lighting control section ( 130 ). The object position detecting section ( 110 ) specifies an object which is present in the periphery of the vehicle and about which a warning is to be issued, and the object position detecting section detects a positional relationship between the object and the vehicle. The lighting control section ( 130 ) controls a headlight ( 120 ) so that illuminating light having a color corresponding to the positional relationship is applied to a region in which the object is present.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a vehicle lighting apparatus and lighting method. More particularly, the present invention relates to a vehicle lighting apparatus and lighting method for making pedestrians around a subject vehicle or people riding bicycles or two-wheeled vehicles notice the approach of the subject vehicle. 
       BACKGROUND ART 
       [0002]    Many technologies have been proposed heretofore to improve a driver&#39;s vision during the nighttime and so on by adjusting the amount of light radiated from lighting such as headlights or the place to illuminate according to the driving state. 
         [0003]    For example, patent literature 1 discloses a technology for improving a driver&#39;s vision by increasing or reducing the amount of light of an adjustable lamp according to the steering angle (i.e. steering signal) of a vehicle. 
         [0004]    Patent literature 2 discloses a technology for helping a driver find pedestrians, bicycles or two-wheeled vehicles more easily using two-colored headlights. 
         [0005]    Patent literature 3 discloses a technology for helping a driver find pedestrians more easily, by radiating a marking light according to the positions of the pedestrians. 
       CITATION LIST 
     Patent Literature 
     [PTL 1] Japanese Patent Application Laid-Open No. 2001-213227 
       [0006]    [PTL 2] Japanese Patent Application Laid-Open No. HEI10-297357 
       [PTL 3] Japanese Patent Application Laid-Open No. 2006-176020 
     SUMMARY OF INVENTION 
     Technical Problem 
       [0007]    Now, in order to prevent a collision of a vehicle and a pedestrian for example, it is important for the driver of the vehicle to recognize the pedestrian and operate the vehicle to avoid a collision, and, in addition, it is also important for the pedestrians to recognize the approach of the vehicle and take actions to avoid a collision. For example, when a vehicle runs at a high speed, it is difficult for the vehicle to stop abruptly or change the traveling direction abruptly, so that, oftentimes, pedestrians as well as the vehicle are required to take escaping actions. 
         [0008]    However, a conventional vehicle lighting apparatus is designed primarily from the perspective of improving the driver&#39;s vision, and not much thought is given to the perspective of making pedestrians or people riding bicycles or two-wheeled vehicles (hereinafter collectively referred to by the word “pedestrian”) notice the approach of the vehicle. 
         [0009]    Especially, during the nighttime, when pedestrians are illuminated by headlights, the brightness of the lights makes it difficult for the pedestrians to know the distance with the approaching vehicle, and consequently the pedestrians have greater difficulty taking escaping actions. 
         [0010]    It is therefore an object of the present invention to provide a vehicle lighting apparatus that allows pedestrians to notice the approach of a vehicle as compared with heretofore. 
       Solution to Problem 
       [0011]    One aspect of a vehicle lighting apparatus according to the present invention employs a configuration having: a headlight that changes a color of radiated light for every area to illuminate; an object position detecting section that identifies a target that is present around a subject vehicle and subject to a warning, and detects a position relationship between the target subject to the warning and the subject vehicle; and a lighting control section that controls the headlight so that a radiated light of a color corresponding to the position relationship, is radiated to an area in which the target subject to the warning is present. 
         [0012]    One aspect of a lighting method according to the present invention includes the steps of: identifying a target that is present around a subject vehicle and subject to a warning, and detecting a position relationship between the target subject to the warning and the subject vehicle; determining a level of danger for the target subject to the warning, based on the position relationship and information about speed of the subject vehicle; and controlling a color to radiate to the target subject to the warning based on the level of danger. 
       ADVANTAGEOUS EFFECTS OF INVENTION 
       [0013]    With the present invention, a target subject to a warning (e.g. pedestrian) is able to know the position relationship with a vehicle based on the color of the light radiated from the vehicle. As a result, as compared with heretofore, it is possible to allow a pedestrian to notice the approach of a vehicle. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0014]      FIG. 1  is a block diagram showing a configuration of a vehicle lighting apparatus according to embodiment 1 of the present invention; 
           [0015]      FIG. 2A  shows an example of a configuration of headlights, and 
           [0016]      FIG. 2B  illustrates radiation of light by the headlights; 
           [0017]      FIG. 3  shows an example of general radiation of light; 
           [0018]      FIG. 4  shows an example of general radiation of light; 
           [0019]      FIG. 5  shows an example of radiation of light according to an embodiment; 
           [0020]      FIG. 6  shows a case where a pedestrian is in an area in which the pedestrian can be detected; 
           [0021]      FIG. 7  shows a case where a pedestrian is present inside an area in which the pedestrian can be detected and outside an area that can be illuminated regularly by headlights; 
           [0022]      FIG. 8  shows a case where a pedestrian is present in a position where a collision with the pedestrian can be avoided by a regular stop operation; 
           [0023]      FIG. 9  shows a case where a pedestrian is present in a position where an abrupt stop is necessary; 
           [0024]      FIG. 10  shows collectively the adjustment of color and the area to illuminate, in each case in  FIG. 6  through  FIG. 9 ; 
           [0025]      FIG. 11A  shows how an entire illuminated area is divided, and 
           [0026]      FIG. 11B  shows areas illuminated by left and right headlights; and 
           [0027]      FIG. 12  is a flowchart of operations of a vehicle lighting apparatus. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0028]    Now, embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 
       (1) Overall Configuration 
       [0029]      FIG. 1  illustrates a principal-part configuration of a vehicle lighting apparatus according to an embodiment of the present invention. Vehicle lighting apparatus  100  is mounted in a means of transportation (that is, a vehicle) which people ride, such as a four-wheeled vehicle or two-wheeled vehicle. 
         [0030]    Vehicle lighting apparatus  100  has object position detecting section  110 , headlight  120 , and lighting control section  130 . 
         [0031]    Object position detection  110  identifies targets that are present around a subject vehicle and subject to a warning, and detects the position relationships between these warning targets and the subject vehicle. To be more specific, object position detecting section  110  identifies targets that are subject to a warning, such as pedestrians outside the vehicle or people riding bicycles and two-wheeled vehicles (referred to as “pedestrians”), and outputs information S 1  about the position relationships between the identified pedestrians and the subject vehicle. This position relationship information S 1  includes information about the distances between the pedestrians and the subject vehicle and information about the directions of the pedestrians as seen from the subject vehicle. 
         [0032]    The above function of object position detecting section  110  is made possible using, for example, an image sensor that acquires images outside the vehicle and an image processing circuit that identifies pedestrians using techniques such as pattern matching based on images acquired by the image sensor. A radar or laser means may be used to identify pedestrians and acquire information about position relationships. Furthermore, when a pedestrian carries a transmitter with him/her, by receiving that signal, it is possible to identify the pedestrian and acquire position relationship information without acquiring images. That is to say, object position detecting section  110  may be designed in any way as long as it can determine the position relationship of a pedestrians and a subject vehicle. 
         [0033]    Lighting control section  130  has light color adjusting section  131 , light-illuminated area control section  132  and danger level determining section  133 . 
         [0034]    Danger level determining section  133  determines the level of danger with respect to pedestrians (targets that are subject to a warning), based on position relationship information S 1  acquired by object position detecting section  100  and vehicle operation state information S 2  of a subject vehicle acquired by a vehicle operation detecting section. To be more specific, the shorter the distance from a subject vehicle to a pedestrian, or the faster the speed of the subject vehicle, the higher danger level determining section  133  determines the level of danger. However, various methods may be used to determine the level of danger. For example, danger level determining section  133  may determine the level of danger higher when a pedestrian nears the traveling direction of a subject vehicle. For example, in Japan, the light radiated from headlights is directed slightly to the left so as not to direct the radiation of light to the driver of an oncoming vehicle. Consequently, the driver of a subject vehicle is more likely to miss a pedestrian that is present to the left with respect to the vehicle&#39;s traveling direction than a pedestrian that is present to the right. Taking this into account, the danger level of a pedestrian that is present to the right with respect to the traveling direction of a vehicle may be increased. Danger level determining section  133  sends out danger level information S 3 , which is a determined result, to light color adjusting section  131  and light-illuminated area control section  132 . 
         [0035]    Light color adjusting section  131  adjusts the color of light radiated to an area where a target subject to a warning is present, based on position relationship information S 1  acquired in object position detecting section  110  and danger level information S 3  acquired in danger level determining section  133 . In practice, the color of light to radiate is determined in headlight  120 , and light color adjusting section  131  forms color control signal S 4  for controlling the color of the light to be radiated from headlight  120 . 
         [0036]    Light color adjusting section  131  of the present embodiment adjusts the color of the light to be radiated to pedestrians to be an advancing color. An advancing color refers to a color that looks close in human sight. 
         [0037]    Whether a color is an advancing color varies depending on the color and brightness of the background. When the background is dark (during the night time, for example), warm colors such as red and yellow look closer than cool colors such as blue and green, so that warm colors are advancing colors. On the other hand, when the background is bright (during the daytime, for example), cool colors such as blue and green look closer than warm colors such as red and yellow, so that cool colors are advancing colors. 
         [0038]    Consequently, as an advancing color, light color adjusting section  131 , preferably, selects a warm color in a dark environment and selects a cool color in a bright environment. For example, it is possible to detect the brightness of the surroundings using an optical sensor and change an advancing color from a cool color to a warm color as the environment becomes darker. 
         [0039]    The present embodiment presumes radiation of light in a stat where the outside is dark (for example, during the nighttime), and is designed to use a warm color such as red and yellow as an advancing color. 
         [0040]    When the level of danger of a target subject to a warning increases, based on danger level information S 3 , light color adjusting section  131  controls the light to radiate to the warning target to a color of a higher degree of warmness. For example, by preparing two thresholds th 1  and th 2 , between which the relationship th 1 &lt;th 2  holds, control may be used so that the same white light as for other areas is radiated to a target subject to a warning when the level of danger is below first threshold th 1 , a yellow light is radiated to the warning target when the level of danger equals or exceeds first threshold th 1  and yet is below second threshold th 2 , and a red light is radiated to the warning target when the level of danger equals or exceeds second threshold th 2 . 
         [0041]    Although a case has been described with the present embodiment where the color to radiate to a target subject to a warning is controlled according to the level of danger, it is equally possible to control the color to radiate to a warning target based on the distance between the warning target and a subject vehicle. That is to say, the light to radiate to a target subject to a warning may be controlled to a color of a higher degree of warmness when the distance to the warning target is shorter. 
         [0042]    Light color adjusting section  131  adjusts the colors of light to radiate to targets that are subject to a warning in this way, on a per warning target basis. 
         [0043]    Light-illuminated area control section  132  controls the advancing color, the color of which is adjusted in light color adjusting section  131 , to be radiated on or near the head of a pedestrian, based on vehicle operation state information S 2  including information about the speed of a subject vehicle, steering angle, tilt of the vehicle and so on, and position relationship information S 1  acquired by object position detecting section  110 , Light-illuminated area control section  132  sends out control signal S 5  showing the color to radiate from headlight  120  and the area to illuminate with that color, to headlight section  120 . 
         [0044]    Headlight  120  may be main headlights provided in all general vehicles, or may be secondary headlights provided apart from main headlights. 
         [0045]    Headlight  120  uses an LED, halogen light, or organic EL (electro-luminescence) light as a lighting source, providing a configuration whereby the color of radiated light can be changed per light-illuminated area. 
         [0046]      FIG. 2A  shows an example of a configuration of headlight  120 , and  FIG. 2B  shows a schematic view of radiation of light by headlight  120 . Headlight  120  of  FIG. 2A  has left and right LED lamps  121 -R and  121 -L having a plurality of lighting sources  123 , and LED driver  122  that drives LED lamps  121 -R and  121 -L. 
         [0047]    LED driver  122  receives as input control signal S 5  from light-illuminated area control section  132  ( FIG. 1 ). 
         [0048]    Where there are a plurality of LED lighting sources  123 , LED driver  122  makes a lighting source in a position designated by control signal S 5  radiate a light of a color designated by control signal S 5 . For example, when pedestrians, which are targets subject to a warning, are present in areas AR 1  and AR 2  in  FIG. 2B , LED lighting source  123 -R and  123 -L are made to illuminate these areas AR 1  and AR 2  with an advancing color. LED lighting sources other than LED lighting sources  123 -R and  123 -L may be made to radiate a white light. 
         [0049]    The configuration of headlight  120  is by no means limited to the configuration in  FIG. 2A  as long as light of specific colors can be radiated to specific areas. 
       (2) Operations 
       [0050]    Next, the operations of vehicle lighting apparatus  100  will be explained. 
         [0051]    First,  FIG. 3  and  FIG. 4  show general examples of radiation of light. During the nighttime, vehicle  10  runs radiating light from headlight  11  to light-illuminated area  12  shown in the drawings. When pedestrian  13  enters the light-illuminated area, that is, light-illuminated area  12 , the driver of vehicle  10  can recognize pedestrian  13 . 
         [0052]      FIG. 5  shows an example of radiation of light by vehicle lighting apparatus  100  according to the present embodiment. Upon detecting pedestrian  13  using object position detecting section  110  ( FIG. 1 ), vehicle lighting apparatus  100  radiates light  14 , the color of which is adjusted based on the distance between pedestrian  13  and a subject vehicle (or the level of danger), to pedestrian  13 . 
         [0053]      FIG. 5  shows an example in which pedestrian  13  crosses the road ahead of the vehicle from the right to the left. Light of a uniform color is radiated from regular headlights, to light-illuminated area  12 . By contrast with this, from headlight  120  of the present embodiment, light  14 , the color of which is adjusted based on the level of danger or distance, is radiated on or near the head of pedestrian  13 . By this means, pedestrian  13  notices the approach of the vehicle. In addition, pedestrian  13  knows the level of danger, distance and so on from the color of radiated light  14 . 
         [0054]    Next, an example of a light distribution operation of vehicle lighting apparatus  100  in four cases will be described.  FIG. 6  to  FIG. 9  show examples of position relationships between subject vehicle  10  and pedestrian  13  in individual cases, and  FIG. 10  shows collectively the adjustment of color and the area to illuminate in each case. 
         [0055]    Case  1 : As shown in  FIG. 6 , this is a case where pedestrian  13  is present outside an area where detection by object position detection section  110  is possible. In this case, vehicle lighting apparatus  100  radiates a regular color (that is, a white light). 
         [0056]    Case  2 : As shown in  FIG. 7 , this is a case where pedestrian  13  is present in an area where detection by object position detection section  110  is possible, and outside the area that can be illuminated regularly by headlight  120  (that is, outside the area designated to be illuminated regularly taking into account the driver&#39;s vision). In this case, vehicle lighting apparatus  100  radiates an orange light, for example, to an area including the head of pedestrian  13 . 
         [0057]    Case  3 : As shown in  FIG. 8 , this is a case where pedestrian  13  is present in a position (i.e. a position of a low level of danger) where subject vehicle  10  does not hit pedestrian  13  provided that subject vehicle  10  performs a regular stop operation. In this case, vehicle lighting apparatus  100  radiates a red light to an area including the head of pedestrian  13 . 
         [0058]    Case  4 : As shown in  FIG. 9 , this is a case where pedestrian  13  is present in a position (i.e. a position of a high level of danger) where subject vehicle  10  needs to stop abruptly. In this case, vehicle lighting apparatus  100  radiates a red light to an area including the whole person of pedestrian  13 . 
         [0059]    By controlling the color of radiated light based on the position of pedestrian  13  in this way, it is possible to make pedestrian  13  notice the approach of subject vehicle  10  without making pedestrian  13  surprised unnecessarily. 
         [0060]    Next, using  FIG. 11 , examples of division of a light-illuminated area and color adjustment will be explained using  FIG. 11 . 
         [0061]      FIG. 11A  shows division of the entire area to be illuminated by vehicle lighting apparatus  10 , and  FIG. 11B  shows areas illuminated by left and right headlights  120 -L and  120 -R.  FIG. 11  shows an example of dividing the entire area to illuminate, into twelve light-illuminated areas &lt; 1 &gt; to &lt; 12 &gt;. 
         [0062]    As shown in  FIG. 11A , there are objects such a bicycle, pedestrians, a road sign, and an oncoming vehicle ahead of the vehicle. Furthermore, as shown in  FIG. 11B , the area illuminated by headlight  120  is divided into: &lt; 1 &gt; upper left area; &lt; 2 &gt; upper center area; &lt; 3 &gt; middle left area; &lt; 4 &gt; middle center area; &lt; 5 &gt; ground-level left area; &lt; 6 &gt; ground-level center area; &lt; 7 &gt; upper center area; &lt; 8 &gt; upper right area; &lt; 9 &gt; middle center area; &lt; 10 &gt; center right area; &lt; 11 &gt; ground-level center area; and &lt; 12 &gt; ground-level right area, so that headlight  120  is able to radiate lights in colors adjusted individually for each area. Codes in  FIG. 11A  and  FIG. 11B  are mutually associated. 
         [0063]    In the example of  FIG. 11A , pedestrians are present in area &lt; 3 &gt; and area &lt; 8 &gt;, so that an advancing color needs to be radiated over &lt; 3 &gt; middle left area and &lt; 8 &gt; upper right area. 
         [0064]      FIG. 12  is a flowchart for explaining the operations of vehicle lighting apparatus  100  according to the present embodiment. 
         [0065]    Vehicle lighting apparatus  100 , upon starting operating in step ST  0 , waits until headlight  120  is switched on in step ST  1 . When headlight  120  is switched on in step ST  1 , the step moves to step ST  2  and object position detecting section  110  acquires images of the surroundings of a subject vehicle. 
         [0066]    In following step ST  3 , object position detecting section  110  determines, for every object in the images, whether or not an object is a target that is subject to a warning. To be more specific, object position detecting section  110  determines the kinds of objects based on the images of the objects acquired, using techniques such as pattern matching. If the kind of an object is determined to be an object with a person such as a pedestrian, bicycle or two-wheeled vehicle (“pedestrian”), for example, that object is determined to be a target that is subject to a warning. If an object is determined to be a target subject to a warning in step ST  3 , the step moves to step ST  4 , or, if an object is determined not to be a target subject to a warning, the step moves to step ST  7 . 
         [0067]    In step ST  4 , danger level determining section  133  determines the danger level of a target that is subject to a warning. 
         [0068]    In step ST  5 , based on the danger level of the target subject to a warning, light color adjusting section  131  adjusts the color of the light to radiate to that warning target. 
         [0069]    In step ST  6 , light-illuminated area control section  132  determines the area to illuminate by the color-adjusted light. 
         [0070]    In step ST  7 , headlight  120  radiates light. 
         [0071]    Then a light, the color of which is adjusted based on the level of danger, is radiated on the warning target. On the other hand, a white light is radiated to areas where there are no targets subject to a warning. 
         [0072]    Next, in step ST  8 , vehicle lighting apparatus  100  determines whether or not headlight  120  is switched off, and, if, headlight  120  is not switched off, the step returns to step ST  12 , or, if headlight  120  is switched off, the step moves to step ST  9 , and the processing is terminated. 
       (3) Effect 
       [0073]    As described above, according to the present embodiment, object position detecting section  110  and lighting control section  130  are provided to specify targets that are present around a subject vehicle and subject to a warning, and to detect the positional relationships of the warning targets and the subject vehicle, so that pedestrians for example are able to know the distance to an approaching vehicle more easily and notice the approach of the vehicle. 
         [0074]    Although a case has been described with the present embodiment where the color of light to radiate to a target that is subject to a warning is adjusted to allow pedestrians to notice the approach of a vehicle, besides the above-described color adjustment, it is also possible to control the luminance and illuminance of headlight  120 . For example, when the distance to a pedestrian nears, the color of the light to radiate to a pedestrian may be controlled to a color of a higher degree of warmness (that is, the color may be changed from yellow to red gradually, for example). However, in addition to this, by controlling the luminance and illuminance, it becomes possible to allow the pedestrian to know better how much the vehicle has approached the pedestrian. For example, the luminance or illuminance of the red light radiated to the pedestrian may be increased as the distance between the pedestrian and the subject vehicle nears. 
         [0075]    The disclosure of Japanese Patent Application No. 2008-180574, filed on Jul. 10, 2008, including the specification, drawings and abstract, is incorporated herein by reference in its entirety. 
       INDUSTRIAL APPLICABILITY 
       [0076]    The present invention is widely applicable to vehicle light apparatus provided in, for example, four-wheeled vehicles and two-wheeled vehicles.