Patent Publication Number: US-2023151942-A1

Title: Vehicle headlight

Description:
TECHNICAL FIELD 
     The present invention relates to a vehicle headlight. 
     BACKGROUND ART 
     As a vehicle headlight typified by an automotive headlight, a vehicle headlight capable of changing a light distribution pattern of emitted light is known. For example, Patent Literature 1 below describes a vehicle headlight including a light source unit including a plurality of light emitting elements and a reflector that repeats a periodic motion, and the reflector forms a predetermined light distribution pattern by reflecting and scanning light from the plurality of light emitting elements. Patent Literature 1 below describes changing a light distribution pattern of emitted light by adjusting emission of light from the plurality of light emitting elements. 
     In addition, conventionally, there is known a vehicle headlight system that detects a light-emitting object that emits light by itself, such as a car ahead, and a retroreflective object that retroreflects light at a predetermined spreading angle without emitting light by itself, such as a road sign. Such a vehicle headlight system is disclosed in Patent Literature 2. The vehicle headlight system disclosed in Patent Literature 2 includes a headlight that alternately repeats light irradiation and non-irradiation, and an imaging unit that captures an image of the front of the self-vehicle at the time of irradiation and at the time of non-irradiation and generates an irradiation image and a non-irradiation image. In addition, the vehicle headlight system includes a detection unit that determines a high luminance portion located in the non-irradiation image as a light-emitting object, and determines a high luminance portion located in the irradiation image but not located in the non-irradiation image as a retroreflective object.
     [Patent Literature 1] WO 2019/073994 A   [Patent Literature 2] JP 2011-110999 A   

     SUMMARY OF INVENTION 
     A vehicle headlight of the present invention includes: a light source unit configured to include a plurality of light emitting elements; a reflector configured to repeat a periodic motion to reflect light from the plurality of light emitting elements and scan the light to form a predetermined light distribution pattern; and a control unit configured to control the light source unit, in which the predetermined light distribution pattern includes a superimposition region where the light from at least two of the light emitting elements is superimposed on each other, and in a case where a signal indicating that a target object located in front of a vehicle is detected is input from a detection device, the control unit controls the light source unit such that a light amount of light emitted from some light emitting elements to a predetermined region overlapping the target object does not change and a light amount of light emitted from other some light emitting element to the predetermined region overlapping the target object changes among the light emitting elements emitting light to the predetermined region overlapping the target object in the superimposition region. 
     In the vehicle headlight, the light distribution pattern of the emitted light changes according to the situation in front of the vehicle, and the light amount of light emitted to the target object changes. In addition, in the vehicle headlight, even in a case where the target object is detected, the light amount of light emitted from some light emitting elements to the predetermined region overlapping the target object does not change. Therefore, in the vehicle headlight, even when the light distribution pattern of the emitted light is changed, the light from some light emitting elements is emitted to the target object. When the light irradiates the target object, the difficulty in visually recognizing the target object can be suppressed and the driving can be facilitated as compared with the case where the light distribution pattern of the emitted light changes and the target object is not irradiated with the light. In addition, in the vehicle headlight, the number of light emitting elements that change the light amount of light emitted is smaller than that in a case where the light amount of light emitted from all the light emitting elements that emit light to the predetermined region overlapping the target object is changed. Therefore, with the vehicle headlight, the control of the light source unit by the control unit can be simplified as compared with such a case. Note that, for example, in a case where the target object is detected by the detection device and the target object is a human such as a pedestrian, the light amount of light emitted to the human changes. For example, when the light amount of light emitted to the human increases, in the vehicle headlight, the human can be easily visually recognized and the driving can be facilitated as compared with the case where the light amount of light emitted to the human does not change. In addition, in a case where the target object is detected by the detection device and the target object is a retroreflective object such as a sign, the light amount of light emitted to the retroreflective object changes. In a case where the retroreflective object reflects the light from the vehicle headlight, the intensity of reflected light from the retroreflective object to the self-vehicle tends to increase as the intensity of light emitted to the retroreflective object increases. For example, when the light amount of light emitted to the retroreflective object is reduced, the intensity of light to the retroreflective object is suppressed and the intensity of reflected light can be suppressed as compared with the case where the light amount of light emitted to the retroreflective object does not change. Therefore, in the vehicle headlight, impartment of glare to the driver of the self-vehicle can be suppressed, and driving can be facilitated. 
     The width of the predetermined region in the left-right direction overlapping the target object may change according to the distance between the vehicle and the target object. 
     From the viewpoint of the driver, the target object looks larger as the distance between the vehicle and the target object is shorter. Therefore, with the above configuration, the light amount of light emitted to the target object can be appropriately changed as compared with the case where the width of the predetermined region in the left-right direction in which the light amount of emitted light changes does not change according to the distance between the vehicle and the target object. 
     In a case where the target object is a human, the control unit may control the light source unit such that the light amount of light emitted from the other some light emitting elements to the predetermined region overlapping the target object increases. 
     With such a configuration, the human can be easily visually recognized and the driving can be facilitated as compared with the case where the light amount of light emitted to the human such as a pedestrian does not change. 
     In a case where the target object is a retroreflective object, the control unit may control the light source unit such that the light amount of light emitted from the other some light emitting elements to the predetermined region overlapping the target object decreases. 
     With such a configuration, impartment of glare to the driver of the self-vehicle can be suppressed and the driving can be facilitated as compared with the case where the light amount of light emitted to the retroreflective object does not change. 
     The control unit may control the light source unit such that the light amount of light emitted from the other some light emitting elements to the predetermined region overlapping the target object changes according to the distance between the vehicle and the target object. 
     With such a configuration, the light amount of light emitted to the target object changes according to the distance between the vehicle and the target object. The driver tends to have difficulty in visually recognizing the human as the distance between the vehicle and the human is longer. Therefore, for example, the farther the distance between the vehicle and the human, the larger the light amount of light emitted to the human. In this case, in the vehicle headlight, the human can be easily visually recognized as compared with the case where the light amount of light emitted to the human does not change according to the distance between the vehicle and the human. In addition, in a case where the retroreflective object reflects the light from the vehicle headlight, the intensity of reflected light from the retroreflective object to the self-vehicle tends to increase as the distance between the self-vehicle and the retroreflective object is shorter. Therefore, for example, the closer the distance between the vehicle and the retroreflective object, the smaller the light amount of light emitted to the retroreflective object. In this case, in the vehicle headlight, impartment of glare to the driver of the self-vehicle can be suppressed as compared with the case where the light amount of light emitted to the retroreflective object does not change according to the distance between the vehicle and the retroreflective object. 
     In a case where the target object is a retroreflective object and the control unit controls the light source unit such that the light amount of light emitted from the other some light emitting elements to the predetermined region overlapping the target object is reduced, the control unit may control the light source unit such that the light amount of light emitted from the other some light emitting elements to the predetermined region overlapping the target object is reduced according to the intensity of light from the target object toward the vehicle. 
     With such a configuration, the impartment of glare to the driver of the self-vehicle can be appropriately suppressed. 
     Alternatively, the control unit may control the light source unit such that the light amount of light emitted from the other some light emitting elements to the predetermined region overlapping the target object decreases as the angle formed by a traveling direction of the vehicle and the direction from the vehicle toward the target object decreases. 
     In general, in a light distribution pattern of light emitted from a vehicle headlight, the intensity of light tends to increase to a center side. Therefore, as the angle between the traveling direction of the vehicle and the direction from the vehicle toward the target object decreases, the intensity of light emitted to the target object tends to increase. Therefore, for example, by controlling the light source unit such that the smaller the angle is, the smaller the light amount of light emitted to the predetermined region overlapping the retroreflective object, which is a target object, the impartment of glare to the driver of the self-vehicle can be appropriately suppressed. 
     When the control unit controls the light source unit such that the light amount of light emitted from the other some light emitting elements to the predetermined region overlapping the target object changes according to the distance between the vehicle and the target object or the intensity of light from the retroreflective object toward the vehicle, the control unit may change the number of the other some light emitting elements to change the light amount of light emitted from the other some light emitting elements to the predetermined region overlapping the target object in a case where the number of the light emitting elements that emit light to the predetermined region overlapping the target object is three or more. 
     The reflector may be a rotary reflector that reflects the light from the plurality of light emitting elements while rotating. 
     A determination unit that determines whether the target object satisfies a predetermined requirement that a light amount of reflected light from the target object is equal to or more than a predetermined value in a case where a signal indicating a state of the target object is input from the detection device is further provided, in which each scanning region through which a spot of light from each light emitting element scanned by the reflector in the predetermined light distribution pattern passes is divided into a pair of end portions that includes an end in a scanning direction and is equal to or more than a width of the spot in the scanning direction and a center portion sandwiched by the pair of end portions, each of the scanning regions is arranged to be displaced in the scanning direction, a part of the center portion of each of the scanning regions overlaps a part of center portions of all the other scanning regions, and the end portion of each of the scanning regions does not overlap the end portion of all the other scanning regions, in a case where the predetermined region moves in the scanning direction from a first state in which the predetermined region is located in the center portion in all the scanning regions corresponding to the other some light emitting elements to a second state in which the predetermined region overlaps the end portion in at least one of the scanning regions corresponding to the other some light emitting elements and is located in the center portion in the scanning region corresponding to at least one of the light emitting elements among the some light emitting elements, the control unit may control the light source unit such that the light amount emitted to the predetermined region from the light emitting element corresponding to the scanning region in which the predetermined region overlaps the end portion in the other some light emitting elements returns to the light amount emitted to the predetermined region in a case where the determination unit does not determine that the target object satisfies the predetermined requirement, and the light amount emitted to the predetermined region in the second state becomes the light amount in the first state by changing the light amount emitted to the predetermined region from at least one of the light emitting elements corresponding to the scanning region in which the predetermined region is located in the center portion among some light emitting elements. 
     In the vehicle headlight, as described above, a light distribution pattern is formed by periodic scanning of light from the plurality of light emitting elements. In such a vehicle headlight, for example, when the predetermined region overlapping the target object is located in the vicinity of an end in the scanning direction of the scanning region through which the spot of light from the light emitting element passes, the distance between this end and the predetermined region may be narrower than the width of the spot in the scanning direction. By the way, the shortest length that allows light scanning is the width of the spot in the scanning direction. Therefore, in the case as described above, the light amount emitted to the predetermined region cannot be changed without changing the light amount emitted between the end and the predetermined region. Therefore, the light amount emitted between the above-described end and the predetermined region is also changed together with the predetermined region, and the region where the light amount is changed may suddenly become large, and the driver may feel a sense of discomfort. On the other hand, in this vehicle headlight, each scanning region corresponding to each light emitting element is divided into a pair of end portions and a center portion, and the width of the end portion is equal to or more than the width of the spot. Then, in the case of the second state in which the end portion of the scanning region corresponding to the light emitting element that emits the light in which the light amount of light emitted to the predetermined region is changed overlaps the predetermined region, the control unit controls the light source unit such that the light amount of light emitted from the light emitting element returns to the light amount emitted to the predetermined region in a case where the determination unit does not determine that the target object satisfies the predetermined requirement. Therefore, with the vehicle headlight, the distance between the predetermined region and the end of the scanning region corresponding to the light emitting element in which the light amount of light emitted to the predetermined region is changed can be prevented from being less than the width of the condensing spot in the scanning direction. In addition, in this case, the control unit controls the light source unit such that the light amount emitted to the predetermined region in the second state becomes the light amount in the first state by changing the light amount emitted to the predetermined region from the light emitting element in which the predetermined region is located in the center portion of the scanning region among the light emitting elements that emit light in which the light amount of light emitted to the predetermined region is not changed. Therefore, with the vehicle headlight, a change in the light amount emitted to the vicinity of the predetermined region can be suppressed, the brightness of the predetermined region can be prevented from changing, and the driver can be suppressed from feeling a sense of discomfort. 
     The predetermined region in the second state may be located in the center portion of the scanning region corresponding to two or more of the light emitting elements among some light emitting elements, and in the case of changing from the first state to the second state, the light amount emitted to the predetermined region from the light emitting element corresponding to the scanning region in which the distance between the center of the center portion in the scanning direction and the predetermined region is the shortest among the two or more of the light emitting elements among some light emitting elements may change. 
     In this vehicle headlight, the light amount of light emitted from the light emitting element corresponding to the scanning region in which the distance between the center of the center portion and the predetermined region is the shortest to the predetermined region changes. Therefore, even when the predetermined region further moves to one side or the other side in the scanning direction, the end portion of the scanning region corresponding to the light emitting element in which the light amount of light emitted to the predetermined region is changed in the case of changing from the first state to the second state and the predetermined region can be made less likely to overlap each other. Accordingly, with the vehicle headlight, it is possible to suppress an increase in the number of times the control unit controls the light source unit as described above. 
     In addition, the state that satisfies the predetermined requirement may be a state in which the distance between the target object and the vehicle is less than the predetermined distance. 
     In addition, the state that satisfies the predetermined requirement may be a state in which the apparent size of the target object is equal to or more than a predetermined value. 
     A vehicle headlight of the present invention includes: a plurality of light source units; a reflector configured to repeat a periodic motion to reflect light from the plurality of light source units and scan the light; and a control unit configured to control the plurality of light source units, in which the reflector reflects the light from the plurality of light source units such that a first light distribution pattern formed by scanning of light from some light source units among the plurality of light source units and a second light distribution pattern formed by scanning of light from other some light source units among the plurality of light source units partially overlap each other in an up-down direction of a vehicle, and in a case where a signal indicating that a retroreflective object located in front of the vehicle is detected is input from a detection device, the control unit controls the plurality of light source units such that the light amount of light emitted to a predetermined region overlapping the retroreflective object in one of the first light distribution pattern and the second light distribution pattern is reduced as compared with a case where a signal indicating that the retroreflective object is not detected is input from the detection device. 
     In a case where the retroreflective object reflects the light, the intensity of reflected light from the retroreflective object to the self-vehicle tends to increase as the intensity of light from the light source units to the retroreflective object increases. Here, a case where the signal indicating that the retroreflective object is detected is input to the control unit from the detection device is compared with the case where the signal indicating that the retroreflective object is not detected is not input to the control unit from the detection device. In a case where the signal indicating that the retroreflective object is detected is input to the control unit, as compared with the case where the signal indicating that the retroreflective object is not detected is not input to the control unit, the light amount of light emitted to the predetermined region overlapping the retroreflective object in one of the first light distribution pattern and the second light distribution pattern is reduced. The light is a part of the light forming one of the first light distribution pattern and the second light distribution pattern. When the light amount of light decreases, the intensity of light to the retroreflective object is suppressed, and the intensity of the reflected light can be suppressed, as compared with the case where the light amount does not decrease. Thus, even when the reflected light travels to the self-vehicle, impartment of glare to the driver of the self-vehicle can be suppressed. Accordingly, with the vehicle headlight, a reduction in driver&#39;s visibility can be suppressed. 
     In addition, a determination unit that determines whether the retroreflective object satisfies the predetermined requirement that the light amount of light reflected from the retroreflective object is equal to or more than the predetermined value in a case where the signal indicating the state of the retroreflective object is input from the detection device is further provided, the light source unit that emits light emitted to the predetermined region includes a plurality of light emitting elements, and the control unit may control the light source unit such that each of the light amount of the light from some light emitting elements among the plurality of light emitting elements and the light amount of the light from other some light emitting elements among the plurality of light emitting elements is reduced in a case where the determination unit determines that the retroreflective object satisfies the predetermined requirement as compared with the case where the determination unit determines that the retroreflective object does not satisfy the predetermined requirement. 
     With the vehicle headlight, in the state in which the retroreflective object satisfies the predetermined requirement, the irradiation of the retroreflective object with light is suppressed, and the intensity of the reflected light can be further suppressed as compared with the state in which the retroreflective object does not satisfy the predetermined requirement. Accordingly, with the vehicle headlight, a reduction in driver&#39;s visibility can be further suppressed. 
     In addition, a determination unit that determines whether the retroreflective object satisfies the predetermined requirement that the light amount of light reflected from the retroreflective object is equal to or more than the predetermined value in a case where the signal indicating the state of the retroreflective object is input from the detection device is further provided, the light source unit that emits light emitted to the predetermined region includes a plurality of light emitting elements, and the control unit may control the light source unit such that the light amount of the light from some light emitting elements among the plurality of light emitting elements is reduced and the light amount of the light from other some light emitting elements among the plurality of light emitting elements becomes the same in a case where the determination unit determines that the retroreflective object satisfies the predetermined requirement as compared with the case where the determination unit determines that the retroreflective object does not satisfy the predetermined requirement. 
     In a case where the retroreflective object satisfies the predetermined requirement and a case where the retroreflective object does not satisfy the predetermined requirement, when the light amount of light from other some light emitting element is the same, the control unit can perform the same control on the other some light emitting element in both cases. For example, even when the state is switched from the case where the retroreflective object does not satisfy the predetermined requirement to the case where the retroreflective object satisfies the predetermined requirement, the control unit may not need to change the amount of power supplied to the other some light emitting elements. Accordingly, the control unit can easily control other some light emitting elements as compared with the case where the light amount of light from other some light emitting elements changes in a case where the retroreflective object satisfies the predetermined requirement and a case where the retroreflective object does not satisfy the predetermined requirement. 
     In addition, the state that satisfies the predetermined requirement may be a state in which the distance between the retroreflective object and the vehicle is less than the predetermined distance. 
     In addition, the state that satisfies the predetermined requirement may be a state in which the apparent size of the retroreflective object is equal to or more than a predetermined value. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a plan diagram conceptually illustrating a vehicle. 
         FIG.  2    is a diagram schematically illustrating one lighting tool of a first embodiment. 
         FIG.  3    is a diagram illustrating a layout of light emitting elements of a light source unit of the first embodiment. 
         FIG.  4    is a diagram illustrating a scanning region through which a condensing spot of light from each light emitting element of the first embodiment passes. 
         FIG.  5    is a diagram illustrating a scanning region of the first embodiment. 
         FIG.  6    is a time chart illustrating a turn-on/turn-off state of the light emitting element of the first embodiment. 
         FIG.  7    is a flowchart illustrating an operation of a vehicle headlight. 
         FIG.  8    is a diagram describing scanning of a condensing spot in Step S 4 . 
         FIG.  9    is a diagram illustrating a predetermined light distribution pattern in Step S 4 . 
         FIG.  10    is a diagram describing scanning of a condensing spot in Step S 5 . 
         FIG.  11    is a diagram illustrating a specific light distribution pattern in Step S 5 . 
         FIG.  12    is a diagram describing a scanning region in a modification of the first embodiment. 
         FIG.  13    is a diagram describing an example of setting of a light amount change region in Step S 5  in the modification of the first embodiment. 
         FIG.  14    is a diagram describing another example of setting of the light amount change region in Step S 5  in the modification of the first embodiment. 
         FIG.  15    is a diagram schematically illustrating one lighting tool of a second embodiment. 
         FIG.  16    is a diagram illustrating a layout of light emitting elements of a plurality of light source units of the second embodiment. 
         FIG.  17    is a diagram illustrating a scanning region through which a condensing spot of light from each light emitting element of the second embodiment passes. 
         FIG.  18    is a diagram illustrating a scanning region of the second embodiment. 
         FIG.  19    is a diagram describing scanning of a condensing spot in Step S 4 . 
         FIG.  20    is a diagram illustrating a first light distribution pattern and a second light distribution pattern in Step S 4 . 
         FIG.  21    is a diagram describing scanning of a condensing spot in Step S 5 . 
         FIG.  22    is a diagram illustrating a first light distribution pattern and a second light distribution pattern in Step S 5 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Preferred embodiments of a vehicle headlight according to the present invention will be described below in detail with reference to the drawings. The embodiments illustrated below are for facilitating the understanding of the present invention, and are not for limiting the interpretation of the present invention. The present invention can be changed or modified without departing from the spirit. In addition, in the present invention, components in the following exemplary embodiments may be appropriately combined. Note that, for easy understanding, some parts may be exaggerated in each drawing. 
     (First Embodiment) 
     A first embodiment as a first aspect of the present invention will be described.  FIG.  1    is a plan diagram conceptually illustrating a vehicle  100 . As illustrated in  FIG.  1   , the vehicle  100  includes a vehicle headlight  10  and a detection device  110 . 
     The vehicle headlight  10  of the present embodiment is a headlight for an automobile. The vehicle headlight  10  mainly includes a pair of lighting tools  20  arranged on the left and right of a front portion of the vehicle  100 , a determination unit  50 , a control unit  60 , and a recording unit  70 . Note that, in the present specification, “right” means the right side in the traveling direction of the vehicle  100 , and “left” means the left side in the traveling direction of the vehicle  100 . 
     The pair of lighting tools  20  has a substantially symmetrical shape in the left-right direction of the vehicle  100 . The pair of lighting tools  20  of the present embodiment emits a low beam or a high beam to the front of the vehicle  100 . The configuration of one lighting tool  20   a  of the pair of lighting tools  20  is the same as the configuration of the other lighting tool  20   b  of the pair of lighting tools  20  except that the shape is substantially symmetrical. Therefore, the configuration of each of the lighting tools  20   a  and  20   b  will be described below using the lighting tool  20   a.    
       FIG.  2    is a diagram schematically illustrating the lighting tool  20   a  of the first embodiment illustrated in  FIG.  1   . As illustrated in  FIG.  2   , the lighting tool  20   a  includes, as main configurations, a light source unit  30 , a reflector  39 , a drive unit  41 , and a projection lens  43 . 
     The light source unit  30  includes a plurality of light emitting elements  35  mounted on a circuit board  33 . The plurality of light emitting elements  35  is arranged in a row along a predetermined direction. As the light emitting element  35 , for example, a light emitting diode (LED) or the like is used.  FIG.  2    illustrates the light source unit  30  including five light emitting elements  35 . Note that the number of the light emitting elements  35  in the light source unit  30  is not particularly limited as long as it is two or more. 
     Power is supplied to each light emitting element  35  via the circuit board  33 . The light amount of light emitted from each light emitting element  35  is adjusted by adjusting the power supplied to each light emitting element  35 . The light is emitted toward the reflector  39 . 
     Examples of the reflector  39  of the present embodiment include a rotary reflector. The reflector  39  is fixed to an output shaft, which is not illustrated, of the drive unit  41 , and rotates about a rotation axis, which is not illustrated, of the drive unit  41  passing through the center of the output shaft by a rotational force from the drive unit  41 . The reflector  39  rotates to repeat a periodic motion. Examples of the drive unit  41  include a motor having an encoder, which is not illustrated, that detects the rotational position of the output shaft from the reference position. The encoder outputs a signal indicating rotational position information such as the detected rotational position of the output shaft to the control unit  60 . Note that the lighting tool  20   a  may include a sensor that detects rotational position information such as the rotational position of the reflector  39  from the reference position instead of the encoder. In this case, the sensor outputs a signal indicating the rotational position information to the control unit  60 . The reflector  39  includes two reflection blades  39   a  that reflect the light from the light source unit  30  toward the projection lens  43 . 
     The projection lens  43  of the present embodiment is an aspherical plano-convex lens. In the projection lens  43 , an incident surface which is a surface on a side on which the light reflected by the reflection blades  39   a  of the reflector  39  is incident is formed in a planar shape, and an emission surface which is a surface on a side from which the incident light is emitted is formed in a convex shape bulging in an emission direction. 
     In the present embodiment, the plurality of light emitting elements  35  of the light source unit  30  emits light toward the reflector  39 , and the reflector  39  rotates. Thus, the reflector  39  repeats the rotational motion that is a periodic motion to reflect the light from the plurality of light emitting elements  35  toward the projection lens  43  side, and scans the light in the left-right direction of the vehicle  100 . When this light passes through the projection lens  43 , is emitted to the front of the vehicle  100 , and scanned in the left-right direction of the vehicle  100 , a predetermined light distribution pattern  350  is formed on a vertical plane  200  in front of the vehicle  100 . Accordingly, the reflector  39  repeats the periodic motion to reflect the light from the plurality of light emitting elements  35  and periodically scan the light to form the predetermined light distribution pattern  350 . The predetermined light distribution pattern  350  illustrated in  FIG.  2    indicates a light distribution pattern of a high beam having a rectangular shape horizontally long in the left-right direction of the vehicle  100 . In the present embodiment, the shape of the reflecting surface of the reflection blades  39   a  that reflect the light from the plurality of light emitting elements  35 , the positions of the plurality of light emitting elements  35  with respect to the reflection blades  39   a , and the like are adjusted so as to form the predetermined light distribution pattern  350 . Although details will be described below, the predetermined light distribution pattern  350  to be formed can be changed by controlling the emission of light from the plurality of light emitting elements  35 . 
     Here, referring back to  FIG.  1   , the description of the vehicle will be continued. 
     The control unit  60  determines whether a control signal from a light switch, which is not illustrated, mounted on the vehicle  100  is input. The control signal is a signal instructing start of emission of light from the light source unit  30  of each of the lighting tool  20   a  and the lighting tool  20   b . In a case where the control signal is input to the control unit  60 , the control unit  60  drives the light source unit  30  and drives the drive unit  41 . In a case where the control signal is not input to the control unit  60 , the control unit  60  stops the driving of the light source unit  30  and stops the driving of the drive unit  41 . 
     The control unit  60  can use, for example, an integrated circuit such as a microcontroller, an integrated circuit (IC), a large-scale integrated circuit (LSI), or an application specific integrated circuit (ASIC), or a numerical control (NC) device. In addition, when the NC device is used, the control unit  60  may use a machine learning device or may not use a machine learning device. 
     The detection device  110  detects a target object located in front of the vehicle  100 . Examples of the target object detected by the detection device  110  include a retroreflective object and an object other than the retroreflective object. The retroreflective object of the present embodiment is an object that does not emit light by itself and retroreflects light emitted to the retroreflective object at a predetermined spreading angle. Examples of such a retroreflective object include a road sign installed in the vicinity of the road. In addition, examples of the object other than the retroreflective object include a vehicle such as a preceding vehicle or an oncoming vehicle, and a human such as a pedestrian. 
     As a configuration of the detection device  110 , the detection device  110  mainly includes, for example, a camera, an image processing unit, a detection unit, and the like, which are not illustrated. The camera is attached to the front portion of the vehicle  100  and captures an image of the front of the vehicle  100 . The captured image captured by the camera includes at least a part of a region irradiated with light emitted from the pair of lighting tools  20 . The image processing unit performs image processing on a captured image captured by the camera. When detecting the target object, the detection unit outputs a signal indicating that the target object is detected to the control unit  60  via the determination unit  50 . Note that the detection unit may directly output the signal to the control unit  60 . In addition, the detection unit detects the state of the target object from the information subjected to the image processing by the image processing unit. Examples of the state of the target object include the presence of the target object, the presence position of the target object in the captured image, the type of the target object, and the ratio of the target object in the captured image. When detecting a target object located in front of the vehicle  100 , the detection device  110  outputs a signal indicating the state of the target object to the determination unit  50  and outputs the captured image to the recording unit  70 . The detection device  110  identifies and detects a retroreflective object and a human as target objects as described below. In addition, when no target object is present in front of the vehicle  100  and the target object is not detected, the detection device  110  outputs a signal indicating that the target object is not detected to the determination unit  50  and outputs the captured image to the recording unit  70 . The signal is also a signal indicating that the target object is not present. Note that the detection device  110  may not output the signal in a case where the target object is not detected. In addition, the target object detected by the detection device  110 , the number of types of target objects, and the configuration of the detection device  110  are not particularly limited. Examples of the configuration of the image processing unit and the configuration of the detection unit include the same configuration as the control unit  60 . In addition, the control unit  60  and at least one of the image processing unit and the detection unit of the detection device  110  may be integrally configured, and the control unit  60  may also serve as at least one of the image processing unit and the detection unit. 
     Next, an example of detection of the presence of a retroreflective object from the captured image will be described. Note that the retroreflective object will be described as a road sign. The recording unit  70  records image data of each road sign in advance. When the target object shown in the captured image corresponds to the image data of the road sign recorded in the recording unit  70 , the detection unit detects the target object as a retroreflective object. As another example of detection, generally, the shape of a road sign is a circle, a rectangle, or a triangle, and the road sign has a combination of colors such as red, white, blue, yellow, black, and green. The detection unit may detect the target object as the retroreflective object as long as the outer shape of the target object shown in the captured image captured by the camera is any of a circle, a rectangle, and a triangle, and the color inside the outer shape of the target object is a combination of the above colors. The above two examples of detection may be combined. In addition, when the retroreflective object is a delineator, the light reflected from the delineator is, for example, orange. When the light from the target object shown in the captured image captured by the camera is orange, the detection unit may detect the target object as a retroreflective object. Note that the detection of the retroreflective object by the detection unit is not limited to the above. 
     Next, an example of detection of the presence of a human from the captured image will be described. The detection unit detects a target object as a human when authenticating the face of the human shown in the captured image. Alternatively, the detection unit may include a human sensor that detects infrared rays near body temperature emitted from a human. In a case where the human sensor detects infrared rays and infrared rays are shown in the captured image, the detection unit may detect a target object that is shown in the captured image and emits infrared rays as a human. Note that the detection of the human by the detection unit is not limited to the above. 
     On the basis of a signal indicating the state of the target object from the detection device  110  that detects the target object located in front of the vehicle  100 , the determination unit  50  determines whether the target object satisfies a predetermined requirement that the light amount of the reflected light from the target object to the self-vehicle is equal to or more than a predetermined value. The state that the predetermined requirement is satisfied indicates, for example, a state in which the distance between the target object and the vehicle  100  is less than the predetermined distance. The predetermined distance is, for example,  30  m. The numerical value of the distance is recorded in the recording unit  70  as a threshold value, and may be appropriately changeable according to the traveling status of the vehicle  100  such as daytime and nighttime, the type of target object, and the like. In addition, the numerical value of the distance may be set for each type of the target object. For example, the determination unit  50  mainly includes a calculation unit and a determination main unit. The calculation unit calculates the distance between the target object and the vehicle  100  on the basis of the above ratio in the state of the target object from the detection device  110 . A signal indicating the calculated distance is output to the determination main unit. The determination main unit reads a predetermined distance, which is a threshold value, from the recording unit  70 , compares the calculated distance with the predetermined distance, and determines whether the calculated distance is larger than the predetermined distance. When the calculated distance is equal to or more than the predetermined distance, the determination main unit determines that the target object does not satisfy the predetermined requirement. In addition, when the calculated distance is less than the predetermined distance, the determination main unit determines that the target object satisfies the predetermined requirement. Then, when the determination main unit determines that the target object satisfies the predetermined requirement, the determination unit  50  outputs a signal indicating the state of the target object such as the distance calculated by the calculation unit, the presence position of the target object in the captured image, and the type of the target object to the control unit  60 . Examples of the configuration of the determination unit  50  include the same configuration as the control unit  60 . Note that the control unit  60  and the determination unit  50  may be integrally configured, and the control unit  60  may also serve as the determination unit  50 . 
     The recording unit  70  records the captured image output from the detection device  110  and the predetermined distance, which is the threshold value described above, in the determination unit  50 . Examples of the recording unit  70  include a semiconductor memory such as ROM and a magnetic disk. 
       FIGS.  3  and  4    are diagrams describing formation of the predetermined light distribution pattern  350 . 
       FIG.  3    is a diagram illustrating a layout of light emitting elements  35 - 1  to  35 - 5  of the light source unit  30  of the present embodiment. As described above, the light source unit  30  includes the five light emitting elements  35 - 1  to  35 - 5 . 
       FIG.  4    is a diagram illustrating scanning regions SR 1  to SR 5  through which condensing spots of light pass when the light from the light emitting elements  35 - 1  to  35 - 5  are scanned by the reflector  39  to form the predetermined light distribution pattern  350 . The condensing spot is a spot formed by the light from each of the light emitting elements  35 - 1  to  35 - 5 , and is a spot projected in front of the vehicle  100 . In  FIG.  4   , H represents a horizontal line along the left-right direction of the vehicle  100 , and V represents a vertical line along the up-down direction of the vehicle  100 . A scanning region SR 1  of the present embodiment indicates a region through which a condensing spot formed by light from an i-th (1≤i≤5) light emitting element  35 - i  passes. The scanning regions SR 1  to SR 5  have a rectangular shape horizontally long in the left-right direction of the vehicle  100  and have substantially the same size. The positions of the scanning regions SR 1  to SR 5  in the up-down direction are substantially the same, and the positions in the left-right direction are different. Accordingly, the scanning regions SR 1  to SR 5  are arranged to be displaced from each other in the left-right direction such that a part of each of the scanning regions SR 1  to SR 5  overlaps a part of another scanning region. Note that, in  FIG.  4   , the scanning regions SR 1  to SR 5  are illustrated to be displaced in the up-down direction for easy understanding. The outer shape of the set of scanning regions SR 1  to SR 5  corresponds to the outer shape of the predetermined light distribution pattern  350  illustrated in  FIG.  2   . 
     In the scanning regions SR 1  to SR 5 , the scanning region SR 1  is located on the leftmost side, and the scanning regions SR 1  to SR 5  are arranged to be gradually displaced to the right in the order of the scanning regions SR 1  to SR 5 . Accordingly, the center of the scanning region SR 2  in the left-right direction is located on the right side of the center of the scanning region SR 1  in the left-right direction, and a part of the scanning region SR 2  and a part of the scanning region SR 1  overlap each other. In addition, the center of the scanning region SR 3  in the left-right direction is located on the right side of the center of the scanning region SR 2  in the left-right direction, and a part of the scanning region SR 3  and a part of the scanning regions SR 1  to SR 2  overlap each other. The center of the scanning region SR 4  in the left-right direction is located on the right side of the center of the scanning region SR 3  in the left-right direction, and a part of the scanning region SR 4  and a part of the scanning regions SR 1  to SR 3  overlap each other. The center of the scanning region SR 5  in the left-right direction is located on the right side of the center of the scanning region SR 4  in the left-right direction, and a part of the scanning region SR 5  and a part of the scanning regions SR 1  to SR 4  overlap each other. 
     A center region CA is located at a center portion of the set of the set scanning regions SR 1  to SR 5  in the left-right direction. In the center region CA, parts of the five scanning regions SR 1  to SR 5  overlap each other, and the center region CA can be irradiated with light from the five light emitting elements  35 - 1  to  35 - 5 . In a first left region LS 1  located on the left side of the center region CA, parts of the four scanning regions SR 1  to SR 4  overlap each other, and in a first right region RS 1  located on the right side of the center region CA, parts of the four scanning regions SR 2  to SR 5  overlap each other. In a second left region LS 2  located on the left side of the first left region LS 1 , parts of the three scanning regions SR 1  to SR 3  overlap each other, and in a second right region RS 2  located on the right side of the first right region RS 1 , parts of the three scanning regions SR 3  to SR 5  overlap each other. In a third left region LS 3  located on the left side of the second left region LS 2 , parts of the two scanning regions SR 1  and SR 2  overlap each other, and in a third right region RS 3  located on the right side of the second right region RS 2 , parts of the two scanning regions SR 4  and SR 5  overlap each other. A fourth left region LS 4  located on the left side of the third left region LS 3  includes a part of the scanning region SR 1 , and a fourth right region RS 4  located on the right side of the third right region RS 3  includes a part of the scanning region SR 5 . Therefore, the first left region LS 1  and the first right region RS 1  can be irradiated with the light from the four light emitting elements, and the second left region LS 2  and the second right region RS 2  can be irradiated with the light from the three light emitting elements. In addition, the third left region LS 3  and the third right region RS 3  can be irradiated with the light from the two light emitting elements, and the fourth left region LS 4  and the fourth right region RS 4  can be irradiated with the light from the one light emitting element. 
       FIGS.  5  and  6    are diagrams describing control of the light emitting element  35 - i  in the scanning region SR 1 .  FIG.  5    is a diagram illustrating the scanning region SR 1 . In the scanning region SR 1  illustrated in  FIG.  5   , a non-hatched range indicates a light amount change region  311 , and a hatched range indicates a light amount non-change region  313 . The light amount non-change region  313  is a region where the light amount of light from the light emitting element  35 - i  is substantially a predetermined amount. On the other hand, the light amount change region  311  is a region in which the light amount of light from the light emitting element  35 - i  is different from the light amount of light emitted to the light amount non-change region  313 .  FIG.  6    is a time chart illustrating the light amount of light emitted from the light emitting element  35 - i.  TS illustrated in  FIG.  6    indicates a scanning period. 
     SCi illustrated in  FIG.  5    indicates a position of a condensing spot of light from the light emitting element  35 - i  at a certain time. It is assumed that the condensing spot SCi is scanned from the left to the right in the drawing. It is assumed that a left end LE of the condensing spot SCi is located at the left end of the scanning region SR 1  at a certain time t 0 . The control unit  60  grasps the position of the condensing spot SCi in the scanning region SR 1  on the basis of the rotational position information from the drive unit  41 , and controls the luminance of the light emitting element  35 - i  in synchronization with the rotational position information. Note that, in  FIG.  5   , the size of the condensing spot SCi with respect to the scanning region SR 1  is larger than the actual size for easy understanding. 
     In the light amount non-change region  313 , the control unit  60  controls the luminance of the light emitting element  35 - i  such that the light amount of light emitted from the light emitting element  35 - i  corresponding to the condensing spot SCi becomes a first predetermined value during a period in which the condensing spot SCi passes through the light amount non-change region  313 . The first predetermined value indicates a value of the light amount of light emitted from the light emitting element  35 - i  in the light amount non-change region  313 . In addition, the first predetermined value is, for example, 80% or the like of the maximum value of the light amount of light emitted from the light emitting element  35 - i.    
     In addition, in the light amount change region  311 , the control unit  60  controls the luminance of the light emitting element  35 - i  such that the light amount of light emitted from the light emitting element  35 - i  corresponding to the condensing spot SCi becomes a second predetermined value during a period in which the condensing spot SCi passes through the light amount change region  311 . Specifically, as illustrated in  FIGS.  5  and  6   , the control unit  60  controls the light amount of light emitted from the light emitting element  35 - i  to the second predetermined value at timing to at which a right end RE of the condensing spot SCi reaches the light amount change region  311 . In addition, the control unit  60  controls the light amount of light emitted from the light emitting element  35 - i  to the first predetermined value at timing tB at which the left end LE of the condensing spot SCi reaches the right end of the light amount change region  311 . The second predetermined value indicates a value of the light amount of light emitted from the light emitting element  35 - i  in the light amount change region  311 . The second predetermined value is a value different from the first predetermined value.  FIG.  6    illustrates an example in which the second predetermined value is lower than the first predetermined value. In a case where the second predetermined value is lower than the first predetermined value, the second predetermined value is, for example, 30% or zero or the like of the maximum value of the light amount of light emitted from the light emitting element  35 - i . In addition, the second predetermined value may be made higher than the first predetermined value, and in this case, the second predetermined value is, for example, a maximum value of the light amount of light emitted from the light emitting element  35 - i . When the second predetermined value is zero, the light from the light emitting element  35 - i  is turned off. 
       FIG.  7    is a flowchart illustrating an operation of the vehicle headlight  10  in the present embodiment. As illustrated in  FIG.  7   , the flowchart of the present embodiment includes Steps S 1  to S 5 . 
     (Step S 1 ) 
     The detection device  110  captures an image of the front of the vehicle  100  with a camera. When detecting a target object located in front of the vehicle  100  from the captured image, the detection device  110  outputs a signal indicating that the target object is detected to the control unit  60  via the determination unit  50 , and outputs a signal indicating the state of the target object to the determination unit  50 . In addition, when not detecting a target object located in front of the vehicle  100  from the captured image, the detection device  110  outputs a signal indicating that the target object is not detected to the determination unit  50 . In the present embodiment, the detection device  110  identifies and detects a retroreflective object and a human as target objects. When the signal is input, the processing proceeds to Step S 2 . 
     (Step S 2 ) 
     In the present step, the control unit  60  determines whether to emit the light on the basis of the control signal from the light switch. In a case where the control signal is not input to the control unit  60 , the control unit  60  stops the driving of the plurality of light source units  30  and stops the driving of the drive unit  41 , and the light is not emitted, and the processing returns to Step S 1 . In addition, in a case where the control signal is input to the control unit  60 , the light is emitted, and the processing proceeds to Step S 3 . 
     (Step S 3 ) 
     In the present step, the determination unit  50  determines whether the target object satisfies a predetermined requirement on the basis of the signal indicating the state of the target object from the detection device  110 . In a case where the determination unit  50  determines that the target object does not satisfy the predetermined requirement, the processing proceeds to Step S 4 . In addition, in a case where the signal indicating that the target object is not detected is input to the determination unit  50 , it is determined that the target object does not satisfy the predetermined requirement, and the processing proceeds to Step S 4 . On the other hand, in a case where the determination unit  50  determines that the target object satisfies the predetermined requirement, the determination unit  50  outputs a signal indicating the state of the target object such as the distance between the target object and the vehicle  100  calculated by the calculation unit, the presence position of the target object in the captured image, and the type of the target object to the control unit  60 . When the determination unit  50  outputs the signal, the processing proceeds to Step S 5 . Hereinafter, the state that the predetermined requirement is satisfied will be described as an example in which the distance between the target object and the vehicle  100  is less than a predetermined distance. In addition, in the following description, it is assumed that the target object is located diagonally forward left of the vehicle  100 . 
     (Step S 4 ) 
     In the present step, as described in Step S 3 , the retroreflective object as the target object is detected by the detection device  110 , and the distance between the retroreflective object and the vehicle  100  is equal to or more than the predetermined distance, or the target object is not detected by the detection device  110 . In this case, the control unit  60  controls the driving of the light source unit  30  and also controls the driving of the drive unit  41 .  FIG.  8    is a diagram describing scanning of condensing spots SC 1  to SC 5  in the present step.  FIG.  9    is a diagram illustrating a predetermined light distribution pattern  350  formed when the distance between the retroreflective object  401  as a target object and the vehicle  100  is equal to or more than a predetermined distance. Note that the predetermined light distribution pattern  350  illustrated in  FIG.  9    is the same as the predetermined light distribution pattern  350  illustrated in  FIG.  2   . 
     Here, first, scanning of the condensing spots SC 1  to SC 5  in the present step will be described with reference to  FIG.  8   . In  FIG.  8   , the plurality of scanning regions SR 1  to SR 5  is displaced and arranged for easy viewing. The condensing spots SC 1  to SC 5  scan the scanning regions SR 1  to SR 5  from the left to the right in the drawing. When the distance between the target object and the vehicle  100  is equal to or more than the predetermined distance and when the target object is not detected by the detection device  110 , the control unit  60  sets each of the scanning regions SR 1  to SR 5  as the light amount non-change region  313 . Next, the control unit  60  controls the light emitting elements  35 - 1  to  35 - 5  such that the light amount of light emitted from the light emitting elements  35 - 1  to  35 - 5  corresponding to the condensing spots SC 1  to SC 5  becomes the first predetermined value. 
     When the light emitting elements  35 - 1  to  35 - 5  controlled as described above emit light, the light is reflected toward the projection lens  43  by the reflector  39  rotated by the drive unit  41 . In addition, the light passes through the projection lens  43 , is emitted to the front of the vehicle  100 , and scans in the left-right direction of the vehicle  100 . By this light scanning, the predetermined light distribution pattern  350  is formed in front of the vehicle  100  as illustrated in  FIG.  9   . As illustrated in  FIG.  9   , when the retroreflective object  401  is a road sign installed in the vicinity of the road, the retroreflective object  401  is supported by, for example, a support portion  403  that is a metal pillar erected from the vicinity of the road. In  FIG.  9   , H indicates a horizontal line, the predetermined light distribution pattern  350  is indicated by the thick line, and the predetermined light distribution pattern  350  is a light distribution pattern formed on a vertical plane, for example, 25 m away from the vehicle  100 . In addition, in  FIG.  9   , the left and right edges of each of the scanning regions SR 1  to SR 5  are indicated by the dotted lines. 
     As described above, the center region CA is a region where parts of the scanning regions SR 1  to SR 5  overlap each other. Therefore, the light from the five light emitting elements  35 - 1  to  35 - 5  is superimposed on each other in a region of the predetermined light distribution pattern  350  illustrated in  FIG.  9    overlapping the center region CA. Note that this superimposition of light also includes superimposition of light in human vision. In addition, the light from the four light emitting elements is superimposed on each other in a region of the predetermined light distribution pattern  350  overlapping the first left region LS 1  and the first right region RS 1 , and the light from the three light emitting elements is superimposed on each other in a region of the predetermined light distribution pattern  350  overlapping the second left region LS 2  and the second right region RS 2 . In addition, the light from the two light emitting elements is superimposed on each other in a region of the predetermined light distribution pattern  350  overlapping the third left region LS 3  and the third right region RS 3 , and the light from the one light emitting element forms a region of the predetermined light distribution pattern  350  overlapping the fourth left region LS 4  and the fourth right region RS 4 . As described above, each of the scanning regions SR 1  to SR 5  is set as the light amount non-change region  313 . In this case, in a region of the predetermined light distribution pattern  350  where the number of scanning regions overlapping each other is large, the intensity of light in the predetermined light distribution pattern  350  increases. Therefore, in the light distribution pattern  350 , the intensity of light in a region of the light distribution pattern  350  overlapping the center region CA is the strongest, and the intensity of light is weaker toward the outer side of the light distribution pattern  350  in the left-right direction. In addition, a superimposition region PA that coincides with a region of the predetermined light distribution pattern  350  including the regions CA, LS 1  to LS 3 , and RS 1  to RS 3  is a region where the light from at least two light emitting elements is superimposed on each other, and the predetermined light distribution pattern  350  includes such superimposition region PA. Note that, in  FIG.  9   , the superimposition region PA is indicated by the alternate long and short dash line. 
     (Step S 5 ) 
     In the present step, the retroreflective object as the target object is detected by the detection device  110 , and the distance between the retroreflective object and the vehicle  100  is less than the predetermined distance. In this case, the control unit  60  controls the driving of the light source unit  30  and also controls the driving of the drive unit  41 .  FIG.  10    is a diagram describing scanning of the condensing spots SC 1  to SC 5  in the present step.  FIG.  11    is a diagram illustrating a specific light distribution pattern  360  formed when the distance between the retroreflective object  401  and the vehicle  100  is less than the predetermined distance. In addition, in  FIG.  11   , the left and right edges of each of the scanning regions SR 1  to SR 5  are indicated by the dotted lines. Here, the description will be given assuming that the retroreflective object overlaps the superimposition region PA. 
     In the present step, the control unit  60  sets a region where the retroreflective object overlaps the superimposition region PA as a predetermined region AR on the basis of the signal from the determination unit  50 . As illustrated in  FIG.  11   , the predetermined region AR is a region extending linearly from the upper end to the lower end of the superimposition region PA, and is located in the center region CA. Therefore, in a case where the predetermined region AR is formed in the light distribution pattern  350  illustrated in  FIG.  9   , the light from the five light emitting elements  35 - 1  to  35 - 5  is superimposed on each other in the predetermined region AR. The position of the predetermined region AR in the left-right direction changes according to the position of the retroreflective object  401  in the left-right direction with respect to the vehicle  100 , and in the present embodiment, the center of the predetermined region AR in the left-right direction substantially coincides with the center of the retroreflective object  401  in the left-right direction. Note that the center of the predetermined region AR in the left-right direction may not coincide with the center of the retroreflective object  401  in the left-right direction. In addition, the width of the predetermined region AR in the left-right direction changes according to the distance between the vehicle  100  and the retroreflective object  401 . In the present embodiment, the entire retroreflective object  401  overlaps the predetermined region AR, and the width of the predetermined region AR in the left-right direction is made wider as the distance from the retroreflective object  401  is shorter. Note that the width of the predetermined region AR in the left-right direction may not change according to the distance between the vehicle  100  and the retroreflective object  401 . The width of the predetermined region AR in the left-right direction is narrower than the width of the center region CA, but may be the same as that of the center region CA. 
     Next, as illustrated in  FIG.  10   , in a case where the light distribution pattern  350  illustrated in  FIG.  9    is formed, the control unit  60  does not set the light amount change region  311  in some scanning regions of the scanning regions SR 1  to SR 5  in the light emitting elements  35 - 1  to  35 - 5  that emit light to the predetermined region AR, which is not illustrated in  FIG.  9   , and sets the light amount change region  311  in other some scanning regions. In the present embodiment,  FIG.  10    illustrates a state in which the light amount change region  311  is not set in the three scanning regions SR 1 , SR 3 , and SR 5 , and the light amount change region  311  is set in the two scanning regions SR 2  and SR 4 . Note that in  FIG.  10   , similarly to  FIG.  8   , the plurality of scanning regions SR 1  to SR 5  is displaced and arranged for easy viewing. The light amount change region  311  corresponds to the predetermined region AR, the position of the light amount change region  311  in the left-right direction is the same as that of the predetermined region AR, and the width of the light amount change region  311  in the left-right direction is the same as that of the predetermined region AR. In addition, the control unit  60  sets the light amount non-change region  313  in a region where the light amount change region  311  is not set in each of the scanning regions SR 1  to SR 5 . 
     Note that, in a case where the predetermined region AR is located in the first left region LS 1 , when the light distribution pattern  350  illustrated in  FIG.  9    is formed, the light from the four light emitting elements  35 - 1  to  35 - 4  is superimposed on each other in the predetermined region AR. In this case, in a case where the light distribution pattern  350  illustrated in  FIG.  9    is formed, the control unit  60  does not set the light amount change region  311  in some scanning regions of the scanning regions SR 1  to SR 4  in the light emitting elements  35 - 1  to  35 - 4  that emit light to the predetermined region AR, and sets the light amount change region  311  in other some scanning regions. Therefore, the control unit  60  does not set the light amount change region  311  in some scanning regions of the scanning regions of the light emitting elements that emit light to the predetermined region AR in the light distribution pattern  350  formed when the distance between the target object and the vehicle  100  is equal to or more than the predetermined distance, and sets the light amount change region  311  in other some scanning regions. 
     In addition, when the distance between the target object and the vehicle  100  is less than the predetermined distance, the number of scanning regions in which the light amount change region  311  is set changes according to the distance between the vehicle  100  and the target object. For example, in a case where the target object is the retroreflective object  401 , the number increases as the distance between the vehicle  100  and the retroreflective object  401  is shorter. For example, in a case where the distance between the vehicle  100  and the retroreflective object  401  is shorter than the distance in the state illustrated in  FIG.  11   , the light amount change region  311  in which the distance is larger than that in the state illustrated in  FIG.  10    is set. In this case, for example, the light amount change region  311  is set in the three scanning regions SR 1 , SR 2 , and SR 4 . Note that, for example, in a case where the target object is a human, the number of scanning regions in which the light amount change region  311  is set increases as the distance between the vehicle  100  and the human is longer. Note that the number of scanning regions in which the light amount change region  311  is set may not change according to the distance between the vehicle  100  and a retroreflective object or a human as a target object. In addition, the scanning region where the light amount change region  311  is not set is not particularly limited, and may be changed according to the position of the target object in the left-right direction with respect to the superimposition region PA. 
     In addition, the control unit  60  sets the second predetermined value on the basis of the information from the determination unit  50 . In a case where the target object is a retroreflective object, that is, in a case where a signal indicating that the target object is a retroreflective object is input to the control unit  60 , the control unit  60  sets the second predetermined value to a predetermined value lower than the first predetermined value. Note that, in a case where the target object is a human, that is, in a case where a signal indicating that the target object is a human is input to the control unit  60 , the control unit  60  sets the second predetermined value to be higher than the first predetermined value. In the flowchart illustrated in  FIG.  7   , since the target object is the retroreflective object  401 , the control unit  60  sets the second predetermined value to a predetermined value lower than the first predetermined value. 
     Next, in a case where the target object is the retroreflective object  401 , the control unit  60  controls the light emitting elements  35 - 1 ,  35 - 3 , and  35 - 5  such that the light amount of light emitted from the light emitting elements  35 - 1 ,  35 - 3 , and  35 - 5  corresponding to the condensing spots SC 1 , SC 3 , and SC 5  for scanning the scanning regions SR 1 , SR 3 , and SR 5  where the light amount change region  311  is not set becomes the first predetermined value. In addition, in a case where the target object is the retroreflective object  401 , the control unit  60  controls the light emitting elements  35 - 2  and  35 - 4  such that the light amount of light emitted from the light emitting elements  35 - 2  and  35 - 4  corresponding to the condensing spots SC 2  and SC 4  becomes the first predetermined value during a period in which the condensing spots SC 2  and SC 5  for scanning the scanning regions SR 2  and SR 4  in which the light amount change region  311  is set pass through the light amount non-change region  313 . In addition, in a case where the target object is the retroreflective object  401 , the control unit  60  controls the light emitting elements  35 - 2  and  35 - 4  such that the light amount of light emitted from the light emitting elements  35 - 2  and  35 - 4  corresponding to the condensing spots SC 2  and SC 4  becomes the second predetermined value during a period in which the condensing spots SC 2  and SC 4  pass through the light amount change region  311 . Then, the processing returns to Step S 1 . 
     When the light emitting elements  35 - 1  to  35 - 5  controlled as described above emit light, the light is reflected toward the projection lens  43  by the reflector  39  rotated by the drive unit  41 . The reflected light passes through the projection lens  43 , is emitted to the front of the vehicle  100 , and scans in the left-right direction of the vehicle  100 . By this light scanning, the specific light distribution pattern  360  illustrated in  FIG.  11    is formed in front of the vehicle  100 . As described above, the light amount of light emitted from the light emitting elements  35 - 2  and  35 - 4  corresponding to the condensing spots SC 2  and SC 4  becomes the second predetermined value lower than the first predetermined value during a period in which the condensing spots SC 2  and SC 4  pass through the light amount change region  311 . Therefore, the light amount emitted from the condensing spots SC 2  and SC 4  to the predetermined region AR changes so as to be smaller than the light amount in a case where the determination unit  50  determines that the retroreflective object does not satisfy the predetermined requirement. Accordingly, when the specific light distribution pattern  360  illustrated in  FIG.  11    is compared with the predetermined light distribution pattern  350  illustrated in  FIG.  9   , the light amount of light emitted to the predetermined region AR in the specific light distribution pattern  360  is smaller than the light amount of light emitted to the region corresponding to the predetermined region AR in the predetermined light distribution pattern  350 , and the light amount of light emitted to the retroreflective object  401  becomes smaller. 
     Here, as described above, in a case where the target object overlaps a region where at least two scanning regions overlap each other, the control unit  60  does not set the light amount change region  311  in some scanning regions, and sets the light amount change region  311  in other some scanning regions. Therefore, in the present step, the control unit  60  controls the light source unit  30  such that the light amount of light emitted from some light emitting elements to the predetermined region AR overlapping the target object does not change and the light amount of light emitted from other some light emitting elements to the predetermined region AR overlapping the target object changes among the light emitting elements that emit light to the predetermined region AR overlapping the target object in the superimposition region PA where the light from at least two light emitting elements in the light distribution pattern  350  illustrated in  FIG.  9    is superimposed on each other. 
     Note that, in the present step, when a human as a target object is detected by the detection device  110  and the determination unit  50  determines that the human satisfies the predetermined requirement, the control unit  60  sets the second predetermined value to be higher than the first predetermined value as described above. In a case where the second predetermined value is higher than the first predetermined value, the light amount emitted from the light emitting elements  35 - 2  and  35 - 4  to the predetermined region AR is larger than the light amount in a case where the determination unit  50  determines that the human does not satisfy the predetermined requirement. When the light amount increases, the light amount emitted to the predetermined region AR overlapping the human in the specific light distribution pattern  360  when the determination unit  50  determines that the human satisfies the predetermined requirement is larger than the light amount emitted to the region corresponding to the predetermined region AR in the predetermined light distribution pattern  350  when the determination unit  50  determines that the human does not satisfy the predetermined requirement. Accordingly, the light amount of light emitted to the human is larger in a state in which the human satisfies the predetermined requirement than in a state in which the human does not satisfy the predetermined requirement. 
     In addition, in the present step, as described above, in a case where the distance between the retroreflective object  401 , which is the target object, and the vehicle  100  is less than the predetermined distance, the number of scanning regions in which the light amount change region  311  is set increases as the distance between the vehicle  100  and the retroreflective object  401  decreases. Therefore, the closer the distance between the vehicle  100  and the retroreflective object  401 , the smaller the light amount of light emitted to the retroreflective object. In addition, as described above, in a case where the distance between the human, which is the target object, and the vehicle  100  is less than the predetermined distance, the number of scanning regions in which the light amount change region  311  is set increases as the distance between the vehicle  100  and the human increases. Therefore, the farther the distance between the vehicle  100  and the human, the larger the light amount of light emitted to the human. Therefore, the control unit  60  controls the light source unit  30  such that the light amount of light emitted from some light emitting elements to the predetermined region AR overlapping the target object does not change and the light amount of light emitted from other some light emitting elements to the predetermined region AR overlapping the target object changes among the light emitting elements that emit light to the predetermined region AR overlapping the target object in the superimposition region PA described above according to the distance between the vehicle  100  and the target object. 
     By the way, for example, in a case where light emitted from a vehicle headlight provided in a self-vehicle irradiates a retroreflective object such as a sign, a part of the light is directed from the retroreflective object to the self-vehicle as reflected light, and glare may be given to the driver of the self-vehicle. In addition, when the light amount of light emitted from the vehicle headlight and irradiating a human such as a pedestrian is small, it may be difficult for the driver to visually recognize the human. Accordingly, there is a demand for easier driving. 
     Therefore, the vehicle headlight  10  of the present embodiment includes the light source unit  30 , the reflector  39 , and the control unit  60  that controls the light source unit  30 . The light source unit  30  includes the plurality of light emitting elements  35 - 1  to  35 - 5 . The reflector  39  repeats the periodic motion to reflect the light from the plurality of light emitting elements  35 - 1  to  35 - 5  and periodically scan the light to form the predetermined light distribution pattern  350 . The predetermined light distribution pattern  350  includes the superimposition region PA where the light from at least two light emitting elements is superimposed on each other. In a case where a signal indicating that the target object located in front of the vehicle  100  is detected is input from the detection device  110 , the control unit  60  controls the light source unit  30  such that the light amount of light emitted from some light emitting elements to the predetermined region AR overlapping the target object does not change and the light amount of light emitted from other some light emitting elements to the predetermined region AR overlapping the target object changes among the light emitting elements that emit light to the predetermined region AR overlapping the target object in the superimposition region PA. 
     In the vehicle headlight  10  of the present embodiment, the light distribution pattern of the emitted light changes according to the situation in front of the vehicle  100 , and the light amount of light emitted to the target object changes. In addition, in the vehicle headlight  10  of the present embodiment, even in a case where a target object is detected, the light amount of light emitted from some light emitting elements to the predetermined region AR overlapping the target object does not change. Therefore, in the vehicle headlight  10  of the present embodiment, even when the light distribution pattern of the emitted light is changed, the light from some light emitting elements is emitted to the target object. When the light irradiates the target object, the difficulty in visually recognizing the target object can be suppressed and the driving can be facilitated as compared with the case where the light distribution pattern of the emitted light changes and the target object is not irradiated with the light. In addition, in the vehicle headlight  10  of the present embodiment, the number of light emitting elements that change the light amount of light emitted is smaller than that in a case where the light amount of light emitted from all the light emitting elements that emit light to the predetermined region AR overlapping the target object is changed. Therefore, with the vehicle headlight  10  of the present embodiment, the control of the light source unit  30  by the control unit  60  can be simplified as compared with such a case. Note that, in a case where the target object is detected by the detection device and the target object is the retroreflective object  401 , for example, as illustrated in  FIG.  11   , the light amount of light emitted to the retroreflective object  401  changes. In a case where the retroreflective object  401  reflects the light from the vehicle headlight  10 , the intensity of reflected light from the retroreflective object  401  to the self-vehicle tends to increase as the intensity of light emitted to the retroreflective object  401  increases. In the vehicle headlight  10  of the present embodiment, since the light amount of light emitted to the retroreflective object  401  is reduced, the intensity of light to the retroreflective object  401  is suppressed and the intensity of reflected light can be suppressed as compared with the case where the light amount of light emitted to the retroreflective object  401  does not change. Therefore, in the vehicle headlight  10  of the present embodiment, impartment of glare to the driver of the self-vehicle can be suppressed, and driving can be facilitated. In addition, in the vehicle headlight  10  of the present embodiment, in a case where the target object is detected by the detection device and the target object is a human, the light amount of light emitted to the human changes. In the vehicle headlight  10  of the present embodiment, the light amount of light emitted to the human increases, and thus, in the vehicle headlight  10 , the human can be easily visually recognized and the driving can be facilitated as compared with the case where the light amount of light emitted to the human does not change. Note that the control unit  60  may determine that the target object is detected when a determination result of the determination unit  50  indicating whether the target object satisfies the predetermined requirement is input. In this case, the detection device  110  may not output the signal indicating that the target object is detected to the control unit  60 . 
     In addition, in the vehicle headlight  10  of the present embodiment, the width of the predetermined region AR in the left-right direction overlapping the target object changes according to the distance between the vehicle  100  and the target object. From the viewpoint of the driver, the target object looks larger as the distance between the vehicle  100  and the target object is shorter. Therefore, with such a configuration, the light amount of light emitted to the target object can be appropriately changed as compared with the case where the width of the predetermined region AR in the left-right direction in which the light amount of emitted light changes does not change according to the distance between the vehicle  100  and the target object. 
     In addition, in the vehicle headlight  10  of the present embodiment, the control unit  60  controls the light source unit  30  such that the light amount of light emitted from some light emitting elements to the predetermined region AR overlapping the target object does not change and the light amount of light emitted from other some light emitting elements to the predetermined region AR overlapping the target object changes among the light emitting elements that emit light to the predetermined region AR overlapping the target object in the superimposition region PA described above according to the distance between the vehicle  100  and the target object. Therefore, the light amount of light emitted to the target object changes according to the distance between the vehicle  100  and the target object. The driver tends to have difficulty in visually recognizing the human as the distance between the vehicle and the human is longer. In the vehicle headlight  10  of the present embodiment, the farther the distance between the vehicle and the human, the larger the light amount of light emitted to the human. Therefore, in the vehicle headlight  10  of the present embodiment, the human can be easily visually recognized and the driving can be facilitated as compared with the case where the light amount of light emitted to the human does not change according to the distance between the vehicle  100  and the human. In addition, in a case where the retroreflective object reflects the light from the vehicle headlight  10 , the intensity of reflected light from the retroreflective object to the self-vehicle tends to increase as the distance between the self-vehicle and the retroreflective object is shorter. In the vehicle headlight  10  of the present embodiment, the closer the distance between the vehicle  100  and the retroreflective object, the smaller the light amount of light emitted to the retroreflective object. Therefore, in the vehicle headlight  10  of the present embodiment, impartment of glare to the driver of the self-vehicle can be suppressed and the driving can be facilitated as compared with the case where the light amount of light emitted to the retroreflective object does not change according to the distance between the vehicle  100  and the retroreflective object. 
     Note that, in Step S 5 , the control unit  60  does not need to control other some light emitting elements such that the light amount of light emitted from other some light emitting elements different from some light emitting elements toward the predetermined region AR overlapping the target object among the light emitting elements that emit light to the predetermined region AR overlapping the target object in the superimposition region PA always becomes the second predetermined value. For example, the control unit  60  may set the light amount change region  311  in a predetermined scanning period. Then, the control unit  60  may control other some light emitting elements such that the light amount of light emitted from other some light emitting elements described above toward the predetermined region AR becomes the second predetermined value in the period in which the condensing spot passes through the light amount change region  311  in the predetermined scanning period. In addition, in a case where the number of other some light emitting elements described above is plural, the light amounts of light emitted from the plurality of light emitting elements toward the predetermined region AR may be different from each other. For example, in a case where other some light emitting elements are the two light emitting elements  35 - 2  and  35 - 4  and the target object is a retroreflective object as in the above embodiment, the control unit  60  may control the two light emitting elements  35 - 2  and  35 - 4  such that the light amount of light emitted from the light emitting element  35 - 2  toward the predetermined region AR becomes the second predetermined value and the light amount of light emitted from the light emitting element  35 - 4  toward the predetermined region AR becomes a third predetermined value lower than the second predetermined value. 
     In addition, in Step S 5 , the control unit  60  does not need to control the light source unit  30  such that the light amount of light emitted from some light emitting elements to the predetermined region AR does not change and the light amount of light emitted from other some light emitting elements to the predetermined region AR changes among the light emitting elements that emit light to the predetermined region AR overlapping the target object in the superimposition region PA according to the distance between the vehicle  100  and the target object. For example, in a case where the detection device  110  can detect a retroreflective object as a target object and can detect the intensity of light directed from the retroreflective object to the vehicle  100 , the control unit  60  may control the light source unit  30  such that the light amount of light emitted from some light emitting elements to the predetermined region AR does not change and the light amount of light emitted from other some light emitting elements to the predetermined region AR decreases among the light emitting elements that emit light to the predetermined region AR overlapping the retroreflective object in the superimposition region PA according to the intensity of light directed from the retroreflective object to the vehicle  100 . With such a configuration, the impartment of glare to the driver of the self-vehicle can be appropriately suppressed. Note that the detection device  110  detects the intensity of light from the retroreflective object toward the vehicle  100  on the basis of, for example, a luminance value in the captured image. In addition, for example, in a case where the detection device  110  can detect a retroreflective object as a target object and can detect an angle formed by the traveling direction of the vehicle  100  and a direction from the vehicle  100  toward the retroreflective object, the control unit  60  may control the light source unit  30  such that, as the angle is smaller, the light amount of light emitted from some light emitting elements to the predetermined region AR does not change, and the light amount of light emitted from other some light emitting elements to the predetermined region AR decreases among the light emitting elements that emit light to the predetermined region AR overlapping the retroreflective object in the superimposition region PA. In general, in a light distribution pattern of light emitted from a vehicle headlight, the intensity of light tends to increase to a center side. Therefore, the intensity of light emitted to the target object tends to increase as the angle described above decreases. Therefore, for example, by controlling the light source unit  30  such that the smaller the angle described above is, the smaller the light amount of light emitted to the predetermined region AR overlapping the retroreflective object is, the impartment of glare to the driver of the self-vehicle can be appropriately suppressed. In addition, in a case where the number of light emitting elements  35  that emit light to the predetermined region AR overlapping the target object is three or more, the control unit  60  may change the number of other some light emitting elements and change the light amount of light emitted from the other some light emitting elements to the predetermined region AR overlapping the target object. 
     In addition, the control unit  60  may change the scanning region in which the light amount change region  311  is set according to the position of the predetermined region AR in the left-right direction. Hereinafter, a modification in which the scanning region in which the light amount change region  311  is set changes will be described. Note that the same or equivalent components as those of the embodiment described above are designated by the same reference numerals and duplicated description will be omitted unless otherwise specified. 
     In the present modification, for example, as illustrated in  FIG.  12   , the scanning regions SR 1  to SR 5  corresponding to the respective light emitting elements  35 - 1  to  35 - 5  are divided into three regions: pairs of end portions EP 1 - 1  to EP 1 - 5  and EP 2 - 1  to EP 2 - 5 , and center portions CP 1  to CP 5  in the left-right direction, which is the scanning direction. Note that, in  FIG.  12   , the scanning regions SR 1  to SR 5  are arranged to be displaced vertically, and the sizes of the pairs of end portions with respect to the respective scanning regions are larger than the actual sizes for easy understanding. 
     One end portions EP 1 - 1  to EP 1 - 5  are regions including the left-side ends of the scanning regions SR 1  to SR 5 . 
     Widths W 1 - 1  to W 1 - 5  in the left-right direction are widths equal to or larger than the widths of the condensing spots SC 1  to SC 5  in the left-right direction, and are, for example, ten times the widths of the condensing spots SC 1  to SC 5  in the left-right direction. The other end portions EP 2 - 1  to EP 2 - 5  are regions including the right-side ends of the scanning regions SR 1  to SR 5 . Widths W 2 - 1  to W 2 - 5  in the left-right direction are widths equal to or larger than the widths of the condensing spots SC 1  to SC 5  in the left-right direction, and are, for example, ten times the widths of the condensing spots SC 1  to SC 5  in the left-right direction. The center portions CP 1  to CP 5  are regions sandwiched between the one end portions EP 1 - 1  to EP 1 - 5  and the other end portions EP 2 - 1  to EP 2 - 5 . 
     The scanning regions SR 1  to SR 5  are arranged to be displaced in the left-right direction, and centers C 1  to C 5  of the center portions CP 1  to CP 5  in the left-right direction are also displaced from each other in the left-right direction. However, a part of each of the center portions CP 1  to CP 5  overlaps a part of the central portions of all the other scanning regions. In addition, the respective end portions EP 1 - 1  to EP 1 - 5  and EP 2 - 1  to EP 2 - 5  do not overlap the end portions of all the other scanning regions. 
       FIG.  13    is a diagram describing an example of setting of the light amount change region  311  in Step S 5  in the present modification. Note that, in  FIG.  13   , the sizes of the pairs of end portions with respect to the respective scanning regions are larger than the actual size for easy understanding. In addition, in  FIG.  13   , the light amount change region  311  is not set in the three scanning regions SR 1 , SR 2 , and SR 3 , and the light amount change region  311  is set in the two scanning regions SR 4  and SR 5  in Step S 5 . In addition, the predetermined region AR is located in the center portions CP 4  and CP 5  of all the scanning regions SR 4  and SR 5  in which the light amount change region  311  is set. Note that, in the example illustrated in  FIG.  13   , the predetermined region AR is also located in the center portions CP 1  to CP 3  of the scanning regions SR 1  to SR 3  in which the light amount change region  311  is not set. In such a state, for example, when the predetermined region AR moves in the left-right direction as the vehicle  100  moves, the light amount change region  311  also moves in the left-right direction. Therefore, as illustrated in  FIG.  14   , in the two scanning regions SR 4  and SR 5 , the end portion and the light amount change region  311  may overlap each other. In other words, in the two scanning regions SR 4  and SR 5 , the end portion may overlap the predetermined region AR. Here, in the example illustrated in  FIG.  14   , one end portion EP 1 - 5  of the scanning region SR 5  and the predetermined region AR overlap, and this predetermined region AR is located in the center portions CP 1  to CP 4  of the scanning regions SR 1  to SR 4 . 
     In a case where the predetermined region AR is changed from a first state illustrated in  FIG.  13    to a second state illustrated in  FIG.  14   , the control unit  60  controls the light source unit  30  in the manner described below. The first state is a state in which the predetermined region AR is located in the center portions CP 4  and CP 5  of all the scanning regions SR 4  and SR 5  in which the light amount change region  311  is set as illustrated in  FIG.  13   . In addition, the second state is a state in which, as illustrated in  FIG.  14   , the predetermined region AR overlaps one end portion EP 1 - 5  of the scanning region SR 5  and is located in the center portions CP 1  to CP 3  of the scanning regions SR 1  to SR 3  in which the light amount change region  311  is not set. The control unit  60  controls the light source unit  30  such that the light amount emitted to the predetermined region AR from the light emitting element corresponding to the scanning region where the end portion and the predetermined region AR overlap among the light emitting elements  35 - 4  and  35 - 5  returns to the light amount emitted to the predetermined region AR before the light amount is changed. Specifically, the control unit  60  removes the light amount change region  311  from the scanning region SR 5  in which the end portion EP 1 - 5  and the predetermined region AR overlap. Therefore, the light amount emitted to the predetermined region AR from the light emitting element  35 - 1  corresponding to the scanning region SR 5  returns to the light amount emitted to the predetermined region AR before the light amount change region  311  is provided in the scanning region SR 5 . That is, the light amount emitted from the light emitting element  35 - 1  to the predetermined region AR returns to the light amount emitted to the predetermined region AR in a case where the determination unit  50  does not determine that the target object satisfies the predetermined requirement. 
     In addition, the control unit  60  controls the light source unit  30  such that the light amount emitted to the predetermined region AR in the second state becomes the light amount in the first state by changing the light amount of light emitted to the predetermined region AR from at least one light emitting element corresponding to the scanning region in which the predetermined region AR is located in the center portion among the light emitting elements  35 - 1  to  35 - 3 . Here, in the present modification, similarly to the above embodiment, the light amount of light emitted from each light emitting element  35 - i  when the condensing spot SCi passes through the light amount non-change region  313  is the first predetermined value. Therefore, the control unit  60  provides the light amount change region  311  in one scanning region corresponding to the scanning region in which the predetermined region AR is located in the center portion among the three scanning regions SR 1  to SR 3 . Here, since the end portions of the three scanning regions SR 1  to SR 3  do not overlap the predetermined region AR, the light amount change region  311  is provided in any one of the three scanning regions SR 1  to SR 3 . In the present modification, the control unit  60  provides the light amount change region  311  in the scanning region SR 2  in which the distance between the predetermined region AR and the centers C 1  to C 3  of the center portions CP 1  to CP 3  in the left-right direction is the shortest among the three scanning regions SR 1  to SR 3 . Therefore, the light amount emitted from the light emitting element  35 - 2  corresponding to the scanning region SR 2  to the predetermined region AR changes, and the light amount emitted to the predetermined region AR in the second state becomes the light amount in the first state. Then, the processing returns to Step S 1  from Step S 5 . Note that it is sufficient if the control unit  60  controls the light source unit  30  such that the light amount emitted to the predetermined region AR in the second state becomes the light amount in the first state by providing the light amount change region  311  in any one of the three scanning regions SR 1  to SR 3 . A method of selecting the scanning region is not particularly limited, and the light amount change region  311  may be provided in a plurality of scanning regions. When the light amount change region  311  is provided in the plurality of scanning regions, the light amount of light emitted from the light emitting element when the condensing spot passes through the light amount change region  311  is adjusted such that the light amount emitted to the predetermined region AR in the second state becomes the light amount in the first state. 
     Here, in the present modification, as in the above-described embodiment, a light distribution pattern is formed by periodic scanning of light from the plurality of light emitting elements  35 - 1  to  35 - 5 . In such a vehicle headlight, for example, when the predetermined region AR overlapping the target object is located in the vicinity of an end in the scanning direction of the scanning region SR 1  through which the condensing spot SCi of light from the light emitting element  35 - i  passes, the distance between this end and the predetermined region AR may be narrower than the width of the condensing spot SCi in the scanning direction. By the way, the shortest length that allows light scanning is the width of the condensing spot SCi in the scanning direction. Therefore, in the case as described above, the light amount emitted to the predetermined region AR cannot be changed without changing the light amount emitted between the end and the predetermined region AR. Therefore, the light amount emitted between the above-described end and the predetermined region AR is also changed together with the predetermined region AR, and the region where the light amount is changed may suddenly become large, and the driver may feel a sense of discomfort. 
     The vehicle headlight  10  of the present modification further includes the determination unit  50  that determines whether the target object satisfies the predetermined requirement that the light amount of light reflected from the target object is equal to or more than the predetermined value when a signal indicating the state of the target object is input from the detection device  110 . In addition, in the vehicle headlight  10  of the present modification, as described above, the scanning regions SR 1  to SR 5  through which the condensing spots SC 1  to SC 5  of the light from the light emitting elements  35 - 1  to  35 - 5  scanned by the reflector  39  in the predetermined light distribution pattern  350  pass are divided into the pairs of end portions EP 1 - 1  to EP 1 - 5  and EP 2 - 1  to EP 2 - 5  and the center portions CP 1  to CP 5 . One end portions EP 1 - 1  to EP 1 - 5  are regions including the left-side ends of the scanning regions SR 1  to SR 5 , and the other end portions EP 2 - 1  to EP 2 - 5  are regions including the right-side ends of the scanning regions SR 1  to SR 5 . The center portions CP 1  to CP 5  are regions sandwiched between the one end portions EP 1 - 1  to EP 1 - 5  and the other end portions EP 2 - 1  to EP 2 - 5  in the scanning direction. The widths of the end portions EP 1 - 1  to EP 1 - 5  and EP 2 - 1  to EP 2 - 5  in the scanning direction in the scanning regions SR 1  to SR 5  are equal to or larger than the widths of the condensing spots SC 1  to SC 5  in the scanning direction. The scanning regions SR 1  to SR 5  are arranged to be displaced in the scanning direction, a part of the center portions CP 1  to CP 5  of the scanning regions SR 1  to SR 5  overlaps a part of the center portions of all the other scanning regions, and the end portions EP 1 - 1  to EP 1 - 5  and EP 2 - 1  to EP 2 - 5  of the scanning regions SR 1  to SR 5  do not overlap the end portions of all the other scanning regions. Then, in a case where the predetermined region AR is changed from the first state to the second state, the control unit  60  controls the light source unit  30  in the manner described below. The first state here is a state in which the predetermined region AR is located in the center portions CP 4  and CP 5  of all the scanning regions SR 4  and SR 5  corresponding to the light emitting elements  35 - 4  and  35 - 5  in which the light amount of light emitted to the predetermined region AR is changed. In addition, the second state is a state in which the predetermined region AR overlaps an end portion of at least one scanning region corresponding to the light emitting elements  35 - 4  and  35 - 5  in which the light amount of light emitted to the predetermined region AR is changed as the predetermined region AR moves in the scanning direction, and the predetermined region AR is located in the center portion in the scanning region corresponding to at least one light emitting element of the light emitting elements  35 - 1  to  35 - 3  in which the light amount of light emitted to the predetermined region AR is not changed. The control unit  60  controls the light source unit  30  such that the light amount emitted to the predetermined region AR from the light emitting element  35 - 5  corresponding to the scanning region SR 5  in which the predetermined region AR overlaps the end portion among the light emitting elements  35 - 4  and  35 - 5  in which the light amount of light emitted to the predetermined region AR is changed returns to the light amount emitted to the predetermined region AR in a case where the determination unit  50  does not determine that the target object satisfies the predetermined requirement. Therefore, with the vehicle headlight  10  of the present modification, the distance between the predetermined region AR and the end of the scanning region corresponding to the light emitting element in which the light amount of light emitted to the predetermined region AR is changed can be prevented from being less than the width of the condensing spot in the scanning direction. In addition, the control unit  60  controls the light source unit  30  such that the light amount emitted to the predetermined region AR in the second state becomes the light amount in the first state by changing the light amount emitted to the predetermined region AR from at least one light emitting element corresponding to the scanning region in which the predetermined region AR is located in the center portion among the light emitting elements  35 - 1  to  35 - 3  in which the light amount of light emitted to the predetermined region AR is not changed. Therefore, with the vehicle headlight  10  of the present modification, a change in the light amount emitted to the vicinity of the predetermined region AR can be suppressed, the brightness of the predetermined region AR can be prevented from changing, and the driver can be suppressed from feeling a sense of discomfort. 
     In addition, in the vehicle headlight  10  of the present modification, the predetermined region AR in the second state is located in the center portion of the scanning region corresponding to two or more light emitting elements among the light emitting elements  35 - 1  to  35 - 3  in which the light amount of light emitted to the predetermined region AR is not changed. Then, in the case of changing from the first state to the second state, the light amount emitted to the predetermined region AR from the light emitting element  35 - 2  corresponding to the scanning region SR 2  having the shortest distance between the predetermined region AR and the centers C 1  to C 3  in the scanning direction of the center portions CP 1  to CP 3  among the two or more light emitting elements of the light emitting elements  35 - 1  to  35 - 3  in which the light amount of light emitted to the predetermined region AR is not changed changes. Therefore, even when the predetermined region AR further moves to one side or the other side in the scanning direction, the end portion of the scanning region SR 2  corresponding to the light emitting element  35 - 2  in which the light amount of light emitted to the predetermined region AR is changed in the case of changing from the first state to the second state and the predetermined region AR can be made less likely to overlap each other. Accordingly, with the vehicle headlight  10  of the present modification, it is possible to suppress an increase in the number of times the control unit  60  controls the light source unit  30  as described above. 
     Note that, in the present modification, the light amount change region  311  is provided in the scanning regions SR 4  and SR 5  in the first state. However, the scanning region in which the light amount change region  311  is provided and the number of scanning regions in which the light amount change region  311  is provided are not particularly limited. In addition, the length of each scanning region in the scanning direction is also not particularly limited. In addition, the widths of the end portions in these scanning regions may be different from each other or may be the same. In addition, the widths of these scanning regions in a direction perpendicular to the scanning direction may be different from each other or may be the same. In addition, these scanning regions may also be displaced in the scanning direction and also in a direction perpendicular to the scanning direction. In addition, a part of the light distribution pattern may be formed by scanning light from the five light emitting elements  35 - 1  to  35 - 5 , and another part of the light distribution pattern may be formed by scanning light from another light emitting element. 
     (Second Embodiment) 
     Next, a second embodiment as a second aspect of the present invention will be described. Note that the same or equivalent components as those of the first embodiment are designated by the same reference numerals and duplicated description will be omitted unless otherwise specified. In a vehicle headlight  10  of the present embodiment, the configuration of a light source unit  30  in lighting tools  20   a  and  20   b  is different from the configuration of the light source unit  30  in the lighting tools  20   a  and  20   b  of the first embodiment. Since the configurations of the lighting tools  20   a  and  20   b  of the present embodiment are the same, the configurations of the lighting tools  20   a  and  20   b  will be described using the lighting tool  20   a.    
       FIG.  15    is a diagram schematically illustrating the lighting tool  20   a  of the present embodiment. As illustrated in  FIG.  15   , in the lighting tool  20   a  of the present embodiment, a plurality of light source units  30  is arranged. 
     In  FIG.  15   , each light source unit  30  is indicated by the broken line. The broken line is described for convenience in order to illustrate each light source unit  30 , and does not mean that the shape of each light source unit  30  is a broken line-like shape. The light source units  30  are arranged in a row along one direction which is the up-down direction in the sheet of paper of  FIG.  15   . In addition, each light source unit  30  includes a plurality of light emitting elements  35  mounted on a circuit board  33 . The plurality of light emitting elements  35  is arranged in a row along another direction different from the one direction. The other direction is, for example, a direction orthogonal to the one direction.  FIG.  15    illustrates an example in which the two light source units  30  are arranged in a row along the one direction. In addition,  FIG.  15    illustrates an example in which five light emitting elements  35  are arranged in a row along the other direction in some light source unit  30   a  among the plurality of light source units  30 , and two light emitting elements  35  are arranged in a row along the other direction in other some light source unit  30   b . The light source unit  30   a  corresponds to the light source unit  30  of the first embodiment. Note that the number of light source units  30  and the number of light emitting elements  35  in each light source unit  30  are not particularly limited. In addition, for example, each light source unit  30  may be configured to include one light emitting element  35 . 
     In each light source unit  30 , power is supplied to each light emitting element  35  via the circuit board  33 . The light amount of light emitted from each light emitting element  35  is adjusted by adjusting the power supplied to each light emitting element  35 . Light is emitted toward a reflector  39 . Reflection blades  39   a  of the reflector  39  reflect light from the plurality of light source units  30  toward a projection lens  43 . 
     In the present embodiment, when the plurality of light source units  30  emit light toward the reflector  39  and the reflector  39  rotates, the reflector  39  repeats a periodic motion to reflect the light from the plurality of light source units  30  toward the projection lens  43  side, and scans the light in the left-right direction of a vehicle  100 . The light passes through the projection lens  43 , is emitted to the front of the vehicle  100 , and scanned in the left-right direction of the vehicle  100 , and a first light distribution pattern  201  and a second light distribution pattern  203  are formed on a vertical plane  200  in front of the vehicle  100 . The first light distribution pattern  201  is a light distribution pattern formed by scanning the light from the light source unit  30   a , and the second light distribution pattern  203  is a light distribution pattern formed by scanning the light from the light source unit  30   b . The first light distribution pattern  201  partially overlaps the second light distribution pattern  203  in the up-down direction of the vehicle  100 . For example, when the first light distribution pattern  201  and the second light distribution pattern  203  have a rectangular shape horizontally long in the left-right direction of the vehicle  100 , an upper end portion of the first light distribution pattern  201  overlaps a lower end portion of the second light distribution pattern  203 . Here, the reflector  39  reflects the light from the plurality of light source units  30  such that the first light distribution pattern  201  partially overlaps the second light distribution pattern  203  in the up-down direction of the vehicle  100 . Note that, in  FIG.  15   , the first light distribution pattern  201  and the second light distribution pattern  203  are illustrated in a rectangular shape, but the shape of the first light distribution pattern  201  and the second light distribution pattern  203  is not limited to a rectangular shape. 
       FIGS.  16  and  17    are diagrams describing formation of the first light distribution pattern  201  and the second light distribution pattern  203 . 
       FIG.  16    is a diagram illustrating a layout of light emitting elements  35 - 1  to  35 - 7  of the plurality of light source units  30  of the present embodiment. As described above, the light source unit  30   a  includes the five light emitting elements  35 - 1  to  35 - 5 , and the light source unit  30   b  includes the two light emitting elements  35 - 6  to  35 - 7 . 
       FIG.  17    is a diagram illustrating scanning regions SR 1  to SR 7  through which condensing spots of light pass when the light from the light emitting elements  35 - 1  to  35 - 7  is scanned by the reflector  39  to form the first light distribution pattern  201  and the second light distribution pattern  203 . A scanning region SR 1  of the present embodiment indicates a region through which a condensing spot formed by light from an i-th (1≤i≤7) light emitting element  35 - i  passes. A set of the scanning regions SR 1  to SR 5  corresponds to the first light distribution pattern  201 , and a set of the scanning regions SR 6  to SR 7  corresponds to the second light distribution pattern  203 . 
     Since the arrangement of the scanning regions SR 1  to SR 5  of the present embodiment is the same as that of the scanning regions SR 1  to SR 5  of the first embodiment, the description thereof will be omitted. In  FIG.  17   , reference numerals of regions CA, LS 1  to LS 4 , and RS 1  to RS 4  illustrated in  FIG.  4    are omitted for clarity of illustration. 
     The scanning regions SR 6  to SR 7  have a rectangular shape horizontally long in the left-right direction of the vehicle  100  and have substantially the same size. The scanning region SR 6  is wider than the scanning region SR 1 . 
     The positions of the scanning regions SR 6  to SR 7  in the up-down direction are substantially the same, and the positions in the left-right direction are different. Accordingly, the scanning regions SR 6  to SR 7  are arranged to be displaced from each other in the left-right direction such that a part of each of the scanning regions SR 6  to SR 7  overlaps a part of another scanning region. The overlapping region overlaps a vertical line V and is located above a horizontal line H. In addition, a lower end portion of each of the scanning regions SR 6  to SR 7  overlaps a part of an upper end portion of each of the scanning regions SR 1  to SR 5 . The overlapping region is located above the horizontal line H. 
       FIG.  18    is a diagram describing control of the light emitting element  35 - i  in the scanning region SR 1 .  FIG.  18    is a diagram illustrating the scanning region SR 1 . In the scanning region SR 1  illustrated in  FIG.  18   , a non-hatched range indicates a non-irradiation region  211 , and a hatched range indicates an irradiation region  213 . The non-irradiation region  211  indicates a region not irradiated with light in the first light distribution pattern  201  and the second light distribution pattern  203 , or a region irradiated with light in a small light amount not giving glare to the driver of the vehicle  100  by reflected light from a retroreflective object in the first light distribution pattern  201  and the second light distribution pattern  203 . The irradiation region  213  indicates a region irradiated with light in the first light distribution pattern  201  and the second light distribution pattern  203 . The light amount in the irradiation region  213  is larger than the light amount in the non-irradiation region  211 . The time chart of the present embodiment illustrating the turn-on/turn-off state of the light emitting element  35 - i  is the same as the time chart illustrated in  FIG.  6   . 
     In the irradiation region  213 , a control unit  60  controls the luminance of the light emitting element  35 - i  such that the light amount of light emitted from the light emitting element  35 - i  corresponding to the condensing spot SCi becomes a first predetermined value during a period in which the condensing spot SCi passes through the irradiation region  213 . The first predetermined value indicates a value of the light amount of light emitted from the light emitting element  35 - i  in the irradiation region  213 . In addition, the first predetermined value is, for example, the maximum value of the light amount of light emitted from the light emitting element  35 - i,  80% of the maximum value, or the like. 
     In addition, in the non-irradiation region  211 , the control unit  60  controls the luminance of the light emitting element  35 - i  such that the light amount of light emitted from the light emitting element  35 - i  corresponding to the condensing spot SCi becomes a second predetermined value during a period in which the condensing spot SCi passes through the non-irradiation region  211 . Specifically, as illustrated in  FIGS.  6  and  18   , the control unit  60  controls the light amount of light emitted from the light emitting element  35 - i  to the second predetermined value at timing to at which a right end RE of the condensing spot SCi reaches the non-irradiation region  211 , and controls the light amount of light emitted from the light emitting element  35 - i  to the first predetermined value at timing tB at which a left end LE of the condensing spot SCi reaches a right end of the non-irradiation region  211 . The second predetermined value indicates a value of the light amount of light emitted from the light emitting element  35 - i  in the non-irradiation region  211 . The second predetermined value of the present embodiment is a value smaller than the first predetermined value. The second predetermined value is, for example, 30% of the maximum value of the light amount, zero, or the like. When the second predetermined value is zero, the light from the light emitting element  35 - i  is turned off. 
     Next, the operation of the vehicle headlight  10  in the present embodiment will be described. A control flowchart of the operation includes Steps S 1  to S 5  similarly to the control flowchart of the first embodiment. Since Steps S 1  to S 3  of the present embodiment are the same as Steps S 1  to S 3  of the first embodiment, the description thereof will be omitted. Steps S 4  to S 5  of the present embodiment are different from Steps S 4  to S 5  of the first embodiment, and will be described below. Note that a target object of the present embodiment is a retroreflective object located diagonally forward left of the vehicle  100 . In addition, hereinafter, the distance between the retroreflective object and the vehicle  100  may be simply referred to as a distance. 
     (Step S 4 ) 
     In the present step, as in Step S 4  of first embodiment, the retroreflective object is detected by a detection device  110 , and the distance is equal to or more than a predetermined distance, or the retroreflective object is not detected by the detection device  110 . In this case, the control unit  60  controls the driving of the plurality of light source units  30  and also controls the driving of a drive unit  41 .  FIG.  19    is a diagram describing scanning of condensing spots SC 1  to SC 7  in the present step.  FIG.  20    is a diagram illustrating the first light distribution pattern  201  and the second light distribution pattern  203  in a case where the distance is equal to or more than a predetermined distance. The first light distribution pattern  201  and the second light distribution pattern  203  illustrated in  FIG.  20    are the same as the first light distribution pattern  201  and the second light distribution pattern  203  illustrated in  FIG.  15   . 
     Here, first, scanning of the condensing spots SC 1  to SC 7  in the present step will be described with reference to  FIG.  19   . In  FIG.  19   , the plurality of scanning regions SR 1  to SR 7  is displaced and arranged for easy viewing. The condensing spots SC 1  to SC 7  scan the scanning regions SR 1  to SR 7  from the left to the right in the drawing. When the distance is equal to or more than the predetermined distance and when the retroreflective object is not detected by the detection device  110 , the control unit  60  sets each of the scanning regions SR 1  to SR 7  as the irradiation region  213 . Next, the control unit  60  controls the light emitting elements  35 - 1  to  35 - 7  such that the light amount of light emitted from the light emitting elements  35 - 1  to  35 - 7  corresponding to the condensing spots SC 1  to SC 7  becomes the first predetermined value. 
     When the light emitting elements  35 - 1  to  35 - 7  controlled as described above emit light, the light is reflected toward the projection lens  43  by the rotating reflector  39 . In addition, the light passes through the projection lens  43 , is emitted to the front of the vehicle  100 , and scans in the left-right direction of the vehicle  100 . By this light scanning, the first light distribution pattern  201  and the second light distribution pattern  203  are formed in front of the vehicle  100  as illustrated in  FIG.  20   . As illustrated in  FIG.  20   , when a retroreflective object  401  is a road sign installed in the vicinity of the road, the retroreflective object  401  is supported by, for example, a support portion  403  that is a metal pillar erected from the vicinity of the road. In  FIG.  20   , H indicates a horizontal line, the first light distribution pattern  201  and the second light distribution pattern  203  are indicated by the thick lines, and the first light distribution pattern  201  and the second light distribution pattern  203  are a light distribution pattern formed on a vertical plane, for example,  25  m away from the vehicle  100 . The first light distribution pattern  201  partially overlaps the second light distribution pattern  203  in the up-down direction of the vehicle  100 . 
     (Step S 5 ) In the present step, the retroreflective object is detected by the detection device  110 , and the distance is less than the predetermined distance. In this case, the control unit  60  controls the driving of the plurality of light source units  30  and also controls the driving of a drive unit  41 .  FIG.  21    is a diagram describing scanning of condensing spots SC 1  to SC 7  in the present step.  FIG.  22    is a diagram illustrating the first light distribution pattern  201  and the second light distribution pattern  203  in a case where the distance is less than the predetermined distance. Here, the description will be given assuming that the upper end portion of the first light distribution pattern  201  partially overlaps the lower end portion of the second light distribution pattern  203  in the up-down direction of the vehicle  100 , and the retroreflective object overlaps the second light distribution pattern  203 , which is one of the first light distribution pattern  201  and the second light distribution pattern  203 . 
     In the present step, the control unit  60  detects a predetermined region AR where the retroreflective object overlaps in the second light distribution pattern  203  on the basis of a signal from a determination unit  50 , and sets the predetermined region AR as the non-irradiation region  211 . The signal indicates the state of a target object such as the presence position of the retroreflective object. Next, the control unit  60  controls driving of the light source unit  30   a  that emits light for forming the first light distribution pattern  201  and driving of the light source unit  30   b  that emits light for forming the second light distribution pattern  203 . The driving of the light source unit  30   a  and the light source unit  30   b  in the present step will be described below. 
     Here, first, scanning of the condensing spots SC 1  to SC 7  in the present step will be described with reference to  FIG.  21   . In  FIG.  21   , similarly to  FIG.  19   , the plurality of scanning regions SR 1  to SR 7  is displaced and arranged for easy viewing. The condensing spots SC 1  to SC 7  scan the scanning regions SR 1  to SR 7  from the left to the right in the drawing. 
     First, driving of the light source unit  30   a  will be described. The control unit  60  sets each of the scanning regions SR 1  to SR 5  as the irradiation region  213 . Next, the control unit  60  controls the light emitting elements  35 - 1  to  35 - 5  such that the light amount of light emitted from the light emitting elements  35 - 1  to  35 - 5  corresponding to the condensing spots SC 1  to SC 5  becomes the first predetermined value. 
     Next, driving of the light source unit  30   b  will be described. The control unit  60  sets the non-irradiation region  211  in a part of each of the scanning regions SR 6  to SR 7 , and sets the irradiation region  213  in another part of each of the scanning regions SR 6  to SR 7 . The control unit  60  controls the light emitting elements  35 - 6  and  35 - 7  such that the light amount of light emitted from the light emitting elements  35 - 6  and  35 - 7  corresponding to the condensing spots SC 6  and SC 7  becomes the first predetermined value during a period in which the condensing spots SC 6  and SC 7  pass through the irradiation region  213 . In addition, the control unit  60  controls the light emitting elements  35 - 6  and  35 - 7  such that the light amount of light emitted from the light emitting elements  35 - 6  and  35 - 7  corresponding to the condensing spots SC 6  and SC 7  becomes the second predetermined value during a period in which the condensing spots SC 6  and SC 7  pass through the non-irradiation region  211 . 
     When the light emitting elements  35 - 1  to  35 - 7  controlled as described above emit light, the light is reflected toward the projection lens  43  by the rotating reflector  39 . In addition, the light passes through the projection lens  43 , is emitted to the front of the vehicle  100 , and scanned in the left-right direction of the vehicle  100 , and the first light distribution pattern  201  and the second light distribution pattern  203  are formed in front of the vehicle  100 . 
     In the present step, in a case where the determination unit  50  determines that the retroreflective object  401  satisfies a predetermined requirement, the light amount of light emitted to the predetermined region AR overlapping the retroreflective object  401  in the second light distribution pattern  203 , which is one of the first light distribution pattern  201  and the second light distribution pattern  203 , is smaller than that in a case where the determination unit  50  determines that the retroreflective object  401  does not satisfy the predetermined requirement. Thus, the second light distribution pattern  203  is projected in front of the vehicle  100  in a state where the light amount in the retroreflective object  401  is smaller than that in the second light distribution pattern  203  in Step S 4 . 
     Next, an example of control of the second predetermined value will be described using numerical values. The second predetermined value is a value of the light amount of light emitted to the predetermined region AR. The numerical values used here are described for convenience so that the magnitude relationship of the light amount can be easily imaged, and do not indicate actual numerical values of the light amount of light emitted to the predetermined region AR. 
     Here, the description will be given assuming that light emitted from the light emitting element  35 - 6  of the light source unit  30   b  that emits light emitted to the predetermined region AR is referred to as first light, and the light amount of the first light is referred to as a first light amount. In addition, the description will be given assuming that light emitted from the light emitting element  35 - 7  of the light source unit  30   b  is referred to as second light, and the light amount of the second light is referred to as a second light amount. 
     In a case where the distance is equal to or more than the predetermined distance, for example, the control unit  60  controls the light source unit  30   b  such that the first light amount becomes “100” and the second light amount becomes “100”. In this case, the sum of the first light amount and the second light amount is “200”. 
     On the other hand, in a case where the distance is less than the predetermined distance, the control unit  60  controls the light source unit  30   b  such that the first light amount becomes “80” and the second light amount becomes “80”. In this case, the sum of the first light amount and the second light amount is “160”. 
     Next, a comparison between the sum “200” of the first light amount and the second light amount in a case where the distance is equal to or more than the predetermined distance and the sum “160” of the first light amount and the second light amount in a case where the distance is less than the predetermined distance will be described. Comparing the sums, the control unit  60  controls the light source unit  30   b  such that the sum of the first light amount and the second light amount becomes smaller in a case where the distance is less than the predetermined distance than in a case where the distance is equal to or more than the predetermined distance. Next, a comparison between the first light amount “100” and the second light amount “100” in a case where the distance is equal to or more than the predetermined distance and the first light amount “80” and the second light amount “80” in a case where the distance is less than the predetermined distance will be described. Comparing them, the control unit  60  controls the light source unit  30   b  such that each of the first light amount and the second light amount becomes smaller in a case where the distance is less than the predetermined distance than in a case where the distance is equal to or more than the predetermined distance. 
     Note that, in the present embodiment, it is sufficient if the sum of the first light amount and the second light amount becomes smaller in a case where the distance is less than the predetermined distance than in a case where the distance is equal to or more than the predetermined distance as described above. For example, the control unit  60  may control the light source unit  30   b  such that one of the first light amount and the second light amount becomes “80” and the other becomes “100”. Here, a comparison between the first light amount “100” and the second light amount “100” in a case where the distance is equal to or more than the predetermined distance and the first light amount “80” and the second light amount “100” in a case where the distance is less than the predetermined distance will be described. Comparing them, the control unit  60  controls the light source unit  30   b  such that the first light amount becomes smaller and the second light amount becomes the same in a case where the distance is less than the predetermined distance than in a case where the distance is equal to or more than the predetermined distance. 
     When the sum of the first light amount and the second light amount is controlled as described above, the processing returns to Step S 1 . 
     By the way, in a case where light from a vehicle headlight provided in a self-vehicle irradiates a retroreflective object such as a sign, a part of the light is directed from the retroreflective object to the self-vehicle as reflected light, and glare may be given to the driver of the self-vehicle. Thus, there is a concern that the driver&#39;s visibility is reduced. 
     Therefore, the vehicle headlight  10  of the present embodiment includes the plurality of light source units  30 , the reflector  39  that repeats a periodic motion to reflect light from the plurality of light source units  30  and scans the light in the left-right direction of the vehicle  100 , and the control unit  60  that controls the plurality of light source units  30 . The reflector  39  reflects the light from the plurality of light source units  30  such that the first light distribution pattern  201  formed by scanning of light from some light source unit  30   a  of the plurality of light source units  30  and the second light distribution pattern  203  formed by scanning of light from other some light source unit  30   b  of the plurality of light source units  30  partially overlap each other in the up-down direction of the vehicle  100 . When the signal indicating that the retroreflective object located in front of the vehicle  100  is detected is input from the detection device  110 , the control unit  60  controls the plurality of light source units  30  such that the light amount of light emitted to the predetermined region AR overlapping the retroreflective object in the second light distribution pattern  203 , which is one of the first light distribution pattern  201  and the second light distribution pattern  203 , is reduced as compared with the case where the signal indicating that the retroreflective object is not detected is input from the detection device  110 . 
     In a case where the retroreflective object reflects the light, the intensity of reflected light from the retroreflective object to the self-vehicle tends to increase as the intensity of light from the light source units  30  to the retroreflective object increases. Here, a case where the signal indicating that the retroreflective object is detected is input to the control unit  60  from the detection device  110  is compared with the case where the signal indicating that the retroreflective object is not detected is input to the control unit  60  from the detection device  110 . When the signal indicating that the retroreflective object is detected is input to the control unit  60 , as compared with the case where the signal indicating that the retroreflective object is not detected is input to the control unit  60 , the light amount of light emitted to the predetermined region AR overlapping the retroreflective object in the second light distribution pattern  203 , which is one of the first light distribution pattern  201  and the second light distribution pattern  203 , is reduced. The light is a part of the light forming the second light distribution pattern  203 . When the light amount of light decreases, the intensity of light to the retroreflective object is suppressed, and the intensity of the reflected light from the retroreflective object can be suppressed, as compared with the case where the light amount does not decrease. Thus, even when the reflected light travels to the self-vehicle, impartment of glare to the driver of the self-vehicle can be suppressed. Accordingly, with the vehicle headlight  10 , a reduction in driver&#39;s visibility can be suppressed. 
     Note that the vehicle headlight  10  of the present embodiment may further include the determination unit  50  that determines whether the retroreflective object satisfies the predetermined requirement that the light amount of light reflected from the retroreflective object is equal to or more than the predetermined value in a case where the signal indicating the state of the retroreflective object is input from the detection device  110 , and the control unit  60  may control the plurality of light source units  30  such that the light amount of light emitted to the predetermined region AR overlapping the retroreflective object in the second light distribution pattern  203 , which is one of the first light distribution pattern  201  and the second light distribution pattern  203 , is reduced in a case where the determination unit  50  determines that the retroreflective object satisfies the predetermined requirement as compared with the case where the determination unit  50  determines that the retroreflective object does not satisfy the predetermined requirement. Also in this case, as described above, the intensity of light to the retroreflective object is suppressed, and the intensity of light reflected from the retroreflective object can be suppressed. Thus, even when the reflected light travels to the self-vehicle, impartment of glare to the driver of the self-vehicle can be suppressed. Accordingly, with the vehicle headlight  10 , a reduction in driver&#39;s visibility can be suppressed. 
     In addition, in the vehicle headlight  10  of the present embodiment, the light source unit  30   b  that emits light emitted to the predetermined region AR among the plurality of light source units  30  includes the plurality of light emitting elements  35 . The control unit  60  controls the light source unit  30   b  such that each of the light amount of light from some light emitting element  35 - 6  of the plurality of light emitting elements  35  and the light amount of light from other some light emitting element  35 - 7  of the plurality of light emitting elements  35  is reduced in a case where the determination unit  50  determines that the retroreflective object satisfies the predetermined requirement as compared with the case where the determination unit  50  determines that the retroreflective object does not satisfy the predetermined requirement. 
     With the vehicle headlight  10 , in the state in which the retroreflective object satisfies the predetermined requirement, the irradiation of the retroreflective object with light is suppressed, and the intensity of the reflected light can be further suppressed as compared with the state in which the retroreflective object does not satisfy the predetermined requirement. Accordingly, with the vehicle headlight  10 , a reduction in driver&#39;s visibility can be further suppressed. 
     In addition, in the vehicle headlight  10  of the present embodiment, the control unit  60  may control the light source unit  30  such that the light amount of light from some light emitting element  35 - 6  of the plurality of light emitting elements  35  is reduced and the light amount of light from other some light emitting element  35 - 7  of the plurality of light emitting elements  35  is the same in a case where the determination unit  50  determines that the retroreflective object satisfies the predetermined requirement as compared with the case where the determination unit  50  determines that the retroreflective object does not satisfy the predetermined requirement. 
     In a case where the retroreflective object satisfies the predetermined requirement and a case where the retroreflective object does not satisfy the predetermined requirement, when the light amount of light from other some light emitting element  35 - 7  is the same, the control unit  60  can perform the same control on the light emitting element  35 - 7  in both cases. For example, even when the state is switched from the case where the retroreflective object does not satisfy the predetermined requirement to the case where the retroreflective object satisfies the predetermined requirement, the control unit  60  may not need to change the amount of power supplied to the light emitting element  35 - 7 . Accordingly, the control unit  60  can easily control the light emitting element  35 - 7  as compared with the case where the light amount of light from the light emitting element  35 - 7  changes in a case where the retroreflective object satisfies the predetermined requirement and a case where the retroreflective object does not satisfy the predetermined requirement. 
     Although the present invention has been described above by taking the aforementioned embodiments as an example, the present invention is not limited thereto. 
     In each of the above embodiments, the flowchart including Steps S 1  to S 5  has been described as an example, but the flowchart is not particularly limited. 
     The number of reflection blades  39   a  is not particularly limited. 
     It is sufficient if the reflector  39  repeats the periodic motion to reflect the light from the plurality of light source units  30  toward the projection lens  43  side, and scans the light in the left-right direction of the vehicle  100 . The reflector  39  may be, for example, a mirror that is swingable about an axis parallel to the reflecting surface. In addition, for example, the reflector  39  may be a micro electro mechanical system (MEMS) mirror, and the drive unit  41  may be a resonator that is an actuator. 
     It is sufficient if the light source unit  30  of each embodiment is configured to emit light toward the reflector  39 . In addition, similarly to the light source unit  30  of the first embodiment, the light source unit  30  of the second embodiment may further include at least one light emitting element different from the plurality of light emitting elements arranged in a row along the predetermined direction. In this case, the plurality of light emitting elements in the light source unit may be arranged side by side so as to form two or more rows in the predetermined direction. 
     In the light source unit  30   b  of the second embodiment, the light emitted from the light emitting element  35 - 6  may be the second light, and the light emitted from the light emitting element  35 - 7  may be the first light. 
     In the case of the configuration in which the light source unit  30   b  includes only one light emitting element, in a case where the determination unit  50  determines that the retroreflective object satisfies the predetermined requirement, it is sufficient if the control unit  60  controls the light source unit  30   b  such that the light amount of light from the one light emitting element  35  is reduced as compared with the case where the determination unit  50  determines that the retroreflective object does not satisfy the predetermined requirement. 
     In Step S 5  of the second embodiment, the control unit  60  may control the light source unit  30   b  such that the light amount of light emitted from the light emitting elements  35 - 6  and  35 - 7  corresponding to the condensing spots SC 6  and SC 7  becomes zero during a period in which the condensing spots SC 6  and SC 7  pass through the non-irradiation region  211 . Alternatively, the control unit  60  may control the light source unit  30   b  such that the light amount of light emitted from one of the light emitting element  35 - 6  and the light emitting element  35 - 7  becomes zero and the light amount of light emitted from the other of the light emitting element  35 - 6  and the light emitting element  35 - 7  becomes the second predetermined value other than zero. 
     In Step S 5  of the second embodiment, in a case where the distance between the retroreflective object and the vehicle  100  is less than the predetermined distance, it is sufficient if the sum of the light amounts of light emitted to the predetermined region AR overlapping the retroreflective object in the second light distribution pattern  203  may be reduced as compared with the case where the distance between the retroreflective object and the vehicle  100  is equal to or more than the predetermined distance. When the sum of the light amounts decreases, for example, the control unit  60  may control the light source unit  30   b  such that the light amount of light emitted from one of the light emitting element  35 - 6  and the light emitting element  35 - 7  becomes the second predetermined value and the light amount of light emitted from the other of the light emitting element  35 - 6  and the light emitting element  35 - 7  becomes a predetermined value larger than the first predetermined value. Alternatively, the control unit  60  may control the light source unit  30   b  such that the light amount of light emitted from one of the light emitting element  35 - 6  and the light emitting element  35 - 7  becomes the second predetermined value and the light amount of light emitted from the other of the light emitting element  35 - 6  and the light emitting element  35 - 7  becomes the third predetermined value smaller than the second predetermined value. 
     In Step S 5  of the second embodiment, the control unit  60  does not need to control the light emitting elements  35 - 6  and  35 - 7  such that the light amounts of light emitted from the light emitting elements  35 - 6  and  35 - 7  always become the second predetermined value during the light scanning period. For example, the control unit may control the light emitting elements  35 - 6  and  35 - 7  such that the light amount always becomes the second predetermined value in a certain scanning period of the scanning period. Alternatively, the control unit  60  may control the light emitting elements  35 - 6  and  35 - 7  such that the light amount always becomes the second predetermined value in a certain predetermined scanning period of the scanning period. 
     In addition, in Step S 5  of the second embodiment, the control unit  60  may control the light source unit  30   a  such that the light amounts of light emitted from the light emitting elements  35 - 1  to  35 - 5  become the second predetermined value. Alternatively, the control unit  60  may control the light source unit  30   a  such that the light amount of light emitted from the light emitting elements  35 - 1  to  35 - 5  becomes a predetermined value larger than the first predetermined value. In this case, for example, the first predetermined value is 80% of the maximum value of the light amount, and the predetermined value larger than the first predetermined value is the maximum value of the light amount. 
     In the second embodiment, the control unit  60  detects the predetermined region AR where the retroreflective object overlaps in the second light distribution pattern  203  on the basis of the information from the detection device  110  and sets the predetermined region AR as the non-irradiation region  211 , but does not need to be limited thereto. For example, the control unit  60  may detect the predetermined region AR where the face of a human overlaps in the second light distribution pattern  203  on the basis of the information from the detection device  110 , and may set the predetermined region AR as the non-irradiation region  211 . 
     In the second embodiment, it is described that the predetermined region AR overlaps the second light distribution pattern  203 , but even when the predetermined region AR overlaps the first light distribution pattern  201 , it is sufficient if the control unit  60  controls the light source unit  30   b  similarly to the case where the predetermined region AR overlaps the second light distribution pattern  203 . 
     The configuration of the lighting tool  20   a  is the same as the configuration of the lighting tool  20   b , but may be different from the configuration of the lighting tool  20   b.    
     It is sufficient if the captured image is at least one of a moving image and a still image. 
     The detection device  110  detects the presence of the target object, the presence position of the target object, the type of the target object, or the like from the captured image captured by the camera, but does not need to be limited thereto. In a case where a millimeter-wave radar, a LiDAR, or the like capable of detecting a target object is mounted, the detection device  110  may detect the presence of the target object, the presence position of the target object, the type of the target object, or the like on the basis of a signal input from the millimeter-wave radar, the LiDAR, or the like. In addition, the detection device  110  may detect them on the basis of the captured image captured by the camera and the signal input from the millimeter-wave radar, the LiDAR, or the like. In addition, the calculation unit may calculate the distance between the retroreflective object and the vehicle  100  on the basis of the signal input from the millimeter-wave radar or the like. In addition, the detection device  110  may not identify or detect the retroreflective object and the human as a target object, and may detect one of the retroreflective object and the human. In addition, the signal indicating the retroreflective object or the human as a target object may be input to the control unit  60  from a configuration different from the determination unit  50 , for example, the detection device  110 . 
     In addition, the millimeter-wave radar transmits a millimeter wave to a target object and receives a reflected wave that has hit and been reflected from the target object. The millimeter-wave radar outputs a signal indicating a reception result to the calculation unit. The reception result may be included in the state of the target object. The calculation unit may calculate the distance between the vehicle  100  and the target object on the basis of the reception result input from the millimeter-wave radar. 
     In addition, the detection device  110  may include a stereo camera that captures an image of the front of the vehicle  100 . The stereo camera includes two cameras, and outputs captured images captured by the respective cameras to the calculation unit. The captured image may be included in the state of the target object. The calculation unit may calculate the distance between the vehicle  100  and the target object on the basis of stereo matching for obtaining parallax in corresponding pixels that are pixels corresponding to each other in the two captured images. Accordingly, the calculation unit calculates the distance between the vehicle  100  and the target object on the basis of the captured images from the stereo camera. 
     In addition, the detection unit of the detection device  110  may detect a temporal change amount of the size of the target object in the captured image from the captured image on which the image processing is performed by the image processing unit. The change amount is included in the signal indicating the state of the target object. The change amount of the size of the retroreflective object  401  is smaller when the vehicle  100  away from the target object approaches the target object after a lapse of time, and the change amount of the size of the target object is larger when the vehicle moves forward and the vehicle  100  closer to the target object further approaches the target object after a lapse of time. The size of the target object indicates, for example, the area of the target object, the width of the target object, and the like. When detecting a target object located in front of the vehicle  100 , the detection device  110  outputs a signal indicating the state of the target object such as the ratio of the target object in the captured image and the change amount to the calculation unit. The calculation unit may calculate the distance on the basis of the ratio and the change amount. 
     In addition, when the distance between, for example, the retroreflective object  401 , which is a target object, and the vehicle  100  is less than the predetermined distance in a state where the light amount of light emitted from the pair of lighting tools  20  does not change, the intensity of the reflected light from the retroreflective object  401  to the self-vehicle tends to increase as compared with the state where the distance is equal to or more than the predetermined distance. By the way, in the vehicle headlight  10  of the present embodiment, the state that satisfies the predetermined requirement is a state in which the distance between, for example, the retroreflective object  401 , which is a target object, and the vehicle  100  is less than the predetermined distance. In a case where the distance is less than the predetermined distance, the control unit  60  controls the pair of lighting tools  20  as described in the first embodiment or the second embodiment. Accordingly, when the distance is less than the predetermined distance, the intensity of the reflected light traveling from the retroreflective object  401  to the self-vehicle can be suppressed, the impartment of glare can be suppressed, and the reduction in driver&#39;s visibility can be suppressed, as compared with the state where the distance is equal to or more than the predetermined distance. 
     The predetermined requirement is not particularly limited, and may be an apparent size of the target object described above or the like instead of the distance. In a case where the predetermined requirement is the apparent size of the target object, the state that satisfies the predetermined requirement indicates a state in which the apparent size of the target object is equal to or more than a predetermined value. In this case, the detection unit of the detection device  110  detects the size of the target object in the captured image from the captured image on which the image processing is performed by the image processing unit as described above. The determination unit  50  determines whether the target object satisfies the predetermined requirement on the basis of the size of the target object. The predetermined value is recorded in the recording unit  70  as a threshold value, and may be changed according to the traveling status of the vehicle  100  such as daytime and nighttime. Even when the distance between the target object and the vehicle  100  is equal to or more than the predetermined distance, in a case where the apparent size of the target object is equal to or more than the predetermined value, there is a concern that a part of the light from the vehicle  100  travels from the target object to the vehicle  100  as reflected light and gives glare to the driver of the self-vehicle as compared with the case where the apparent size of the target object is less than the predetermined value. As described above, in a case where the state that satisfies the predetermined requirement is a state in which the apparent size of the target object is equal to or more than the predetermined value, the control unit  60  controls the pair of lighting tools  20  as described above. Accordingly, even in a case where the distance between the target object and the vehicle  100  is equal to or more than the predetermined distance and the apparent size of the target object is equal to or more than the predetermined value, the intensity of the reflected light traveling from the target object to the self-vehicle can be suppressed, the impartment of glare can be suppressed, and the reduction in driver&#39;s visibility can be suppressed. In the above description, the apparent size of the target object has been described, but the predetermined requirement may be the ratio of the target object in the captured image. In a case where the predetermined requirement is the ratio, the state that satisfies the predetermined requirement is a state in which the ratio is equal to or more than the predetermined value. 
     In the above description, the state that satisfies the predetermined requirement is a state in which the apparent size of the target object is equal to or more than the predetermined value, but does not need to be limited thereto. For example, the state that satisfies the predetermined requirement may be a state in which any one of the state in which the distance between the target object and the vehicle  100  is less than the predetermined distance, the state in which the apparent size of the target object is equal to or more than the predetermined value, and the state in which the ratio is equal to or more than the predetermined value described in the embodiments is combined. 
     The configuration of the detection device  110  may be included in the configuration of the vehicle headlight  10 . In this case, the camera of the detection device  110  may be arranged inside the enclosure of the lighting tool  20 . 
     When the retroreflective object no longer satisfies the predetermined requirement, the control unit  60  may set the region where the retroreflective object is no longer detected as the light amount non-change region  313  or the irradiation region  213 . 
     As described above, according to the first embodiment of the present invention, the vehicle headlight that enables easy driving is provided, and the vehicle headlight can be used in the field of vehicle headlights such as of automobiles. In addition, according to the second embodiment of the present invention, the vehicle headlight capable of suppressing a reduction in driver&#39;s visibility is provided, and the vehicle headlight can be used in the field of vehicle headlights such as of automobiles.