ROAD SURFACE ILLUMINATING DEVICE FOR VEHICLE

A road surface illuminating device includes an illuminating unit mounted on a vehicle and illuminating a road surface with patterned light, an environmental sensor that detects an obstacle around the vehicle, and an illumination controller that controls the illuminating unit. The illumination controller allows emission of the patterned light that indicates an area where the vehicle passes without interference with the obstacle based on a detection result from the environmental sensor.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2022-193330 filed on Dec. 2, 2022, which is incorporated herein by reference in its entirety including the specification, claims, drawings, and abstract.

TECHNICAL FIELD

The present disclosure relates to a road surface illuminating device for a vehicle.

BACKGROUND

In recent years, technologies have been proposed to transmit information to passengers or other vehicles or pedestrians in the vicinity of a vehicle by illuminating the road surface around the vehicle with patterned light. For example, JP2015-164828 A has disclosed a technology for communicating to passengers or other vehicles or pedestrians in the vicinity a distance between vehicles or whether the vehicle is changing course by illuminating a predetermined shape of patterned light in front of the vehicle. For example, JP2015-164828 A discloses a technology that determines whether a vehicle is changing lanes based on the turn signal lighting status and the steering angle, and, when the vehicle is changing lanes, illuminates patterned light in front of the vehicle that is shaped to proceed from the current travel lane to an adjacent lane after crossing the lane boundary line. According to such technology, the direction of travel of the vehicle can be communicated to the surrounding area, which effectively reduces accidents.

However, the technology described in JP2015-164828 A emits patterned light of a predetermined shape at a predetermined position with reference to the vehicle, regardless of the presence or absence of obstacles in the vicinity. Therefore, the technology described in JP2015-164828 A cannot properly emit the patterned light when there are obstacles around the vehicle. For example, in the above example, when there is an obstacle on the path of the vehicle when changing lanes, the driver naturally selects to travel along a travel path avoiding the obstacle. In JP2015-164828 A, however, the patterned light has a predetermined shape without considering such obstacles. As a result, it may happen that, depending on the presence or absence of obstacles, the actual travel path of the vehicle and the travel path indicated by the patterned light do not match, thus failing to properly communicate the travel path of the vehicle to the driver or other vehicles in the vicinity.

In view of the above, the present disclosure provides a road surface illuminating device capable of more appropriately illuminating the road surface with patterned light.

SUMMARY

A road surface illuminating device disclosed herein includes an illuminating unit mounted on a vehicle and illuminating a road surface with patterned light, an environmental sensor that detects an obstacle around the vehicle, and an illumination controller that controls the illuminating unit, in which the illumination controller allows emission of the patterned light indicating an area where the vehicle passes without interference with the obstacle according to a detection result from the environmental sensor.

Such a structure allows emission of the patterned light indicating the path that the vehicle can actually pass. This enables drivers of the vehicle and other vehicles to easily judge where they should travel in order to avoid contact with each other.

In this case, the patterned light may have a width equal to or greater than the width of the entire vehicle including side mirrors.

Such a structure allows the presence or absence of interference between the vehicle and other vehicles to be determined more clearly.

The illumination controller may also determine the direction of travel of the vehicle based on the speed and steering angle of the vehicle when there is no obstacle in front of the vehicle.

Such a structure allows emission of appropriately shaped patterned light even when there is no obstacle.

The illumination controller may also change the length of the patterned light based on the speed of the vehicle or a relative speed between the vehicle and other vehicles.

The environmental sensor may include a camera.

The vehicle may be an emergency vehicle, and the illumination controller may permit emission of the patterned light only when the vehicle makes an emergency run.

When the emergency vehicle makes an emergency run, it is necessary to inform other vehicles of the area where the emergency vehicle would pass, and ask them to retreat to positions where they do not come in contact with the emergency vehicle. By illuminating the area with patterned light during the emergency run, other vehicles can clearly determine where they should retreat to, thus effectively preventing contact between the emergency vehicle and other vehicles.

In this case, the vehicle is an emergency vehicle, and the illumination controller may allow emission of the patterned light extending in a direction parallel to the lanes while overlapping the roadway center line or lane boundary line while the vehicle makes an emergency run.

Emergency vehicles are permitted to travel while straddling two lanes. Therefore, by allowing emission of the patterned light extending in a direction parallel to the lanes while overlapping the roadway center line or lane boundary line, the patterned light suitable for emergency run can be emitted.

The vehicle may be a non-emergency vehicle, and the illumination controller may specify the shape of the patterned light so that there is no overlap between demarcation lines and the end point of the patterned light and there is no overhang of the patterned light from the demarcation lines where overhang is prohibited.

Such a structure allows emission of the patterned light suitable for non-emergency vehicles.

The illumination controller may provide the patterned light shaped to avoid interference with the obstacle. When the length of the patterned light becomes shorter than a predetermined reference pattern length as a result of avoiding the interference with the obstacle, the illumination controller may issue an alert to passengers of the vehicle.

Such a structure issues an alert when the vehicle comes into a situation where the vehicle is unable to travel properly due to a large number of obstacles. As a result, the driver of the vehicle can easily understand that driving cannot continue properly.

The technology disclosed herein can more appropriately illuminate the road surface with patterned light.

DESCRIPTION OF EMBODIMENTS

Overall Structure

A road surface illuminating device10of a vehicle50will be described with reference to the accompanying drawings.FIG.1is a block diagram illustrating a structure of the road surface illuminating device10.FIG.2is a schematic diagram illustrating how the road surface illuminating device10illuminates the road surface with patterned light40.

Note that the following description is based on the case where left-side driving is prescribed for vehicles. Therefore, vehicles travel in the left lane of the road in principle. In making a right turn, a vehicle crosses the oncoming lane. Of course, the techniques disclosed herein can also be applied to the case where right-side driving is prescribed for the vehicle50.

The road surface illuminating device10is a device that illuminates the road surface in front of a vehicle50with the patterned light40indicating the passing area of the vehicle50. In the following, the road surface illuminating device10mounted on an emergency vehicle is described as an example. Emergency vehicles are vehicles used for highly public and urgent operations such as lifesaving and firefighting response. For example, emergency vehicles include, for example, ambulances, fire trucks, and police vehicles. These emergency vehicles are permitted to make an emergency run under certain conditions where they have priority on the road. During the emergency run, the emergency vehicles are permitted to travel in the oncoming lane (so-called reverse driving) and are exempted from the obligation to stop at traffic signals and the like.

As illustrated inFIG.1, the road surface illuminating device10includes an illuminating unit12, an environmental sensor24, and an illumination controller30. The illuminating unit12emits the patterned light40onto the road surface in front of the vehicle. The illuminating unit12is incorporated, for example, into a headlamp unit (not illustrated) of the vehicle50. The headlamp unit is an illuminating device installed in the vehicle to improve the visibility of the driver of the vehicle50and the visibility of the vehicle50from the outside. The headlamp unit is provided at both ends of the front side of the vehicle50, with one at the right end and one at the left end. The illuminating unit12may be, for example, an adaptive high-beam system unit (hereinafter will be referred to as an “AHS”) incorporated into the headlamp unit. The AHS is an illuminating unit that automatically blocks only a portion of the high-beam light flux illuminating the vehicle ahead or the oncoming vehicle.

FIG.3is a schematic diagram of the illuminating unit12. The illuminating unit12includes an LED array16which acts as a light source14of the illuminating unit12and includes a plurality of LEDs arranged in a matrix. The illumination controller30, which will be described later, controls the lighting state of the plurality of LEDs independently of each other according to the presence or absence of other vehicles around the vehicle50, the shape of the patterned light40to be emitted, and the like.

On the light emitting side of the LED array16, a reflector18and a lens20are arranged in sequence. The light emitted from the LED array16is reflected by the reflector18, refracted by the lens20, and emitted in front of the vehicle. The reflector18can rotate. The illumination controller30controls the rotation of the reflector18according to, for example, the shape of the patterned light40to be emitted. The structure of the illuminating unit12described here is an example and may be modified as necessary. For example, the illuminating unit12may be a projector provided independently of the headlamp unit.

The environmental sensor24is a sensor that detects an obstacle54in front of the vehicle50. The environmental sensor24has, for example, a camera26that captures images of the front of the vehicle. The camera needs to image the front of the vehicle50, and the number and position of the cameras26are not limited. Thus, a total of two cameras26may be mounted, one for each of side mirrors52on the left and right sides of the vehicle50. Alternatively, the camera26may be placed on the front bumper or roof of the vehicle50, and the number of cameras26may not be limited to two and may be changed.

The environmental sensor24may include other sensors in addition to or instead of the camera26. For example, the environmental sensor24may include at least one of an ultrasonic sonar, an infrared sensor, a millimeter wave radar, and a LIDAR. The results of the detection by the environmental sensor24are transmitted to the illumination controller30from time to time.

The illumination controller30is physically a computer with a processor32and a memory34. The “computer” also includes a microcontroller that incorporates the computer system into a single integrated circuit. Although a single processor32and a single memory34are illustrated inFIG.1, the illumination controller30may include two or more processors32and two or more memories34. The illumination controller30may also be composed of a combination of multiple computers physically separated from each other.

The illumination controller30controls the driving of the illuminating unit12to emit the patterned light40onto the road surface. The illumination controller30determines the shape and illuminating position of the patterned light40based on the detection results from the various sensors and the control information of the vehicle50. The illumination controller30receives the detection results from the environmental sensor24. The illumination controller30determines a movable area Amv of the vehicle50based on the detection results from the environmental sensor24. More specifically, the illumination controller30determines the position, shape, and type of the obstacle54around the vehicle by analyzing an image captured by the camera26(hereinafter referred to as a “target image”). Based on the results of this determination, the movable area Amv where the vehicle50can move is determined. The illumination controller30also identifies demarcation lines drawn on the road surface based on the target image. The demarcation lines are lines that represent the boundaries of the lanes and include a roadway center line60c(seeFIG.2) that indicates the boundary between the traveling lane and the oncoming lane, a lane boundary line60b(seeFIG.5) that indicates the boundary between two lanes proceeding in the same direction, and roadway outer lines60s(seeFIGS.2and5) that indicate the edges of the roadway in a width direction. Hereafter, these lines will simply be referred to as “demarcation lines60” when they are not distinguished.

The illumination controller30further receives a turn signal Stn, a vehicle speed Vv, a steering angle Ar, and navigation information Inv. The turn signal Stn is a control signal that is generated in conjunction with lighting of the turn signal lamps (not illustrated). Since turn signal lamps are installed on right and left sides of the vehicle50, there are two types of turn signals Stn, one corresponding to the right side and the other corresponding to the left side. The navigation information Inv is information transmitted from a navigation device (not illustrated) installed in the vehicle50. The navigation information Inv includes, for example, the travel path of the vehicle50that has been set by the passengers.

Next, the emission of the patterned light40by the road surface illuminating device10is described. As mentioned above, the vehicle50in this example is an emergency vehicle. As illustrated inFIG.2, the road surface illuminating device10illuminates the road surface with the patterned light40indicating the passing area of the vehicle50when the vehicle50makes an emergency run. The passing area is the area that the vehicle50is expected to pass through, and has the same width as, or is slightly larger than, the width of the vehicle50. When there is no obstacle54in the passing area, it is considered that the vehicle50can travel smoothly in the passing area. By illuminating the road surface with the patterned light40indicating such a passing area, the driver of the vehicle50can easily judge whether the vehicle50is going to come in contact with the obstacle54. Also, by the emission of the patterned light40, the drivers of other vehicles56a,56bcan easily judge where they should retreat to avoid contact with the vehicle50.

In this example, the illumination controller30determines the movable area Amv where the vehicle50can move based on the detection result from the environmental sensor24, and emits the patterned light40to this movable area Amv, which is explained with reference toFIGS.4and5.FIG.4is a schematic diagram of the image captured by the camera26.FIG.5is a plan view illustrating the emission of the patterned light40. In the following description, the direction in which the vehicle50moves is referred to as a “direction of movement Dmv.” The direction parallel to the lane and downstream of the direction of movement Dmv of the vehicle50is referred to as a “direction of travel Dtr” which is distinguished from the direction of movement Dmv. In the example ofFIG.5, the direction of travel Dtr is from the bottom and straight upward to the upper side of the drawing. On the other hand, in the example ofFIG.5, the vehicle50moves in the upper right direction of the drawing to overtake another vehicle56ahead of it, so this upper right direction of the drawing is the direction of movement Dmv.

When emitting the patterned light40, the illumination controller30determines the movable area Amv based on the detection result from the environmental sensor24. For example, consider the case where the target image illustrated inFIG.4is obtained by the camera26. In this case, the illumination controller30performs various image recognition processing on the target image to extract the obstacles54(which are represented by other vehicles56in the example ofFIG.4) and the demarcation lines60. The obstacles54are intended to include other vehicles56, pedestrians, and structures such as guardrails. The illumination controller30also identifies the location and type of each of the extracted obstacles54and the demarcation lines60. The locations of the obstacles54and the demarcation lines60are identified, for example, by triangulation. The types of obstacles54and demarcation lines60are identified using techniques such as template matching. The illumination controller30identifies the width of a road110, the lane conditions, and the longitudinal direction of the road110(and thus the direction of travel Dtr of the vehicle50) based on the locations and types of the identified demarcation lines60. In addition, the illumination controller30identifies the movable area Amv of the vehicle50based on the locations and types of the identified obstacles54. Specifically, the illumination controller30identifies the area in a space in front of the vehicle50avoiding the obstacles54as the movable area Amv. In the example ofFIG.4, the area shaded by hatched lines is the movable area Amv.

Once the movable area Amv is identified, the illumination controller30identifies the passing area, and thus the shape of the patterned light40, within this movable area Amv. No particular limitation is imposed on this procedure for identifying the shape of the patterned light40. For example, the shape of the patterned light40is identified by the following procedure. The illumination controller30sets a pattern starting point PS having the same width as the patterned light40at a position just in front of the vehicle50, while setting a temporary pattern end point PE* having the same width as the patterned light40at a position distant from the pattern starting point PS by a specified reference pattern length Lp in the downstream direction of the direction of travel Dtr. When all or part of the temporary pattern end point PE* is outside the movable area Amv (not illustrated inFIG.5), the illumination controller30can move the temporary pattern end point PE* in the vehicle width direction so that all of the temporary pattern end point PE* is located within the movable area Amv. When the entire temporary pattern end point PE* is located within the movable area Amv, the obtained temporary pattern end point PE* is set as the final pattern end point PE. Accordingly, a band shape for smoothly connecting the obtained pattern end point PE and the pattern starting point PS is calculated, and the obtained band shape is identified as the shape of the patterned light40.

In a case in which the temporary pattern end point PE* does not fit into the movable area Amv even after moving the temporary pattern end point PE* to the edge of the road110, the illumination controller30repeats the same process by gradually moving the temporary pattern end point PE* closer to the vehicle50until the entire temporary pattern end point PE* is located within the movable area. In this case, naturally, the length of the final patterned light40is shorter than the reference pattern length Lp. Also, it is regarded in this case that the area necessary for the passage of the vehicle50is insufficient. Therefore, when the length of the patterned light40is shorter than the reference pattern length Lp, the illumination controller30may alert the passengers of the vehicle50of this in some manner. For example, the illumination controller30may issue an alert by emitting the patterned light40in a manner different from the usual, for example, in a different color or by blinking, when the length of the patterned light40is short. Alternatively, the illumination controller30may display an alert message on an in-vehicle display when the length of the patterned light40is short.

The illumination controller30emits the patterned light40of the identified shape onto the road surface. This allows the driver of vehicle50to easily recognize a pathway that can be traveled without coming into contact with the obstacle54. On the other hand, the drivers of other vehicles56can clearly know where they should retreat to avoid contact with the vehicle50.

In this example, the vehicle50is the emergency vehicle, and the patterned light40is emitted while the vehicle50is making an emergency run. During the emergency run, the vehicle50is permitted to enter the oncoming lane or to straddle two lanes. In other words, during the emergency run, the vehicle50does not need to comply with the restrictions defined by the roadway center line60cor the lane boundary line60b. Therefore, this example allows emission of the patterned light40extending in a direction parallel to the road110while straddling the roadway center line60cor the lane boundary line60b.

Next, the case in which the vehicle50turns right or left is described.FIG.6is a schematic diagram of the vehicle50making a right turn; that is, turning across an oncoming lane64b, at an intersection. In the case of the right or left turn, the direction of travel Dtr is the direction of the line smoothly connecting the lane in which the vehicle is traveling before making the right or left turn with the lane in which the vehicle enters after making the right or left turn.

In the case of turning right or left, the illumination controller30also identifies the movable area Amv based on the detection result from the environmental sensor24, and emits the patterned light40indicating the passing area of the vehicle50onto the area within this movable area Amv. In the case of the right turn, the patterned light40is curved toward the front of the vehicle50diagonally to the right, as illustrated inFIG.6.

In order to properly emit the patterned light40during the right or left turn, the illumination controller30determines whether the right or left turn is going to be made. For example, the illumination controller30determines whether the right or left turn is going to be made based on the turn signal Stn, the vehicle speed Vv, and the steering angle Ar. Specifically, when either the right or left turn signal Stn is output, the vehicle speed Vv is equal to or less than a predetermined first reference value, and the steering angle Ar is inclined in the same direction as the direction indicated by the turn signal Stn, the illumination controller30determines that the vehicle50is going to turn in the same direction as the direction indicated by the turn signal Stn. The first reference value is the speed at which the vehicle can be considered to be traveling slowly. Alternatively, the illumination controller30may determine whether the right or left turn is going to be made based on the navigation information Inv.

Heretofore, the direction of travel Dtr of the vehicle50has been identified based on the demarcation lines60. However, when no obstacle54is present in front of the vehicle, the illumination controller30may identify the direction of travel Dtr of the vehicle50based on the vehicle speed Vv and the steering angle Ar of the vehicle50, which is explained with reference toFIG.7.FIG.7illustrates a schematic diagram of the vehicle50traveling on a curved road.

InFIG.7, the driver of the vehicle50has turned the steering wheel to the left to drive on a curved road. Naturally, the turn signal Stn is not output at this time. As illustrated inFIG.7, the illumination controller30determines that the vehicle50is traveling on a curved road when the steering angle Ar is tilted while no obstacle54is present in front of the vehicle and the turn signal Stn is not output. In this case, the illumination controller30estimates the direction of travel Dtr of the vehicle50based on the steering angle Ar and the vehicle speed Vv, and determines the passing area, and thus the shape of the patterned light40, based on the estimated direction of travel Dtr.

In the above description, the patterned light40has been emitted during the emergency run of the vehicle50. However, the patterned light40may also be emitted when the vehicle50travels normally. For example, consider the case where the vehicle50is a non-emergency vehicle which does not make an emergency run. Even in such a case, the vehicle50may emit the patterned light40when it overtakes a preceding vehicle or passes through a narrow lane. Such emission of the patterned light40may be performed in response to an instruction from the passenger of the vehicle50. For example, the illumination controller30may emit the patterned light40when the passenger presses a predetermined switch.

Even when the vehicle50is a non-emergency vehicle, the illumination controller30identifies the movable area Amv based on the detection result from the environmental sensor24, and the passing area of the vehicle50and then the shape of the patterned light40is identified within the movable area Amv. However, in the case of non-emergency vehicles, the reverse driving is not permitted, nor is straddling the lane boundary line60b. Furthermore, depending on the color and shape of the roadway center line60c, temporarily straddling the roadway center line60cfor the purpose of overtaking is also prohibited. Therefore, when the vehicle50is the non-emergency vehicle, the illumination controller30identifies the passing area by considering the lane boundary line60band the roadway center line60c.

Specifically, the illumination controller30interprets the regulations meant by the respective lines based on the color and shape of the lane boundary line60band the roadway center line60ccaptured in the image. For example, in Japan, when the demarcation lines60are white, the vehicle50is permitted to overstep the demarcation lines60for overtaking or changing lanes, and when the demarcation lines60are yellow, the vehicle50is prohibited from overstepping the demarcation lines60. In the U.S. and China, when the demarcation lines60are dashed lines, the vehicle50is allowed to overstep the demarcation lines60for overtaking or changing lanes, and when the demarcation lines60are solid lines, the vehicle50is prohibited from overstepping the demarcation lines60. That is, the yellow demarcation lines60indicate no-overstep lines in Japan, while in the U.S. and China, the solid demarcation lines60indicate no-overstep lines. Furthermore, non-emergency vehicles are prohibited from running while straddling two lanes. Therefore, when the vehicle50is a non-emergency vehicle, the illumination controller30specifies the shape of the patterned light40so that there is no overlap between the demarcation lines60and the pattern end point PE and no overhang of the patterned light40from the demarcation lines60where overstepping is prohibited.

The shape of the patterned light40is explained with reference toFIGS.8and9. The driver of the vehicle50judges whether the vehicle50can pass or not based on the relative positional relationship between the patterned light40and the obstacles54. Therefore, the patterned light40is required to have a width close to a vehicle width Wa (seeFIG.8) of the vehicle50. For example, the width of the patterned light40is equal to or greater than a vehicle width Wa of the vehicle50. Side mirrors52of the vehicle50usually protrude outward beyond the vehicle width Wa. To facilitate determination of the risk of contact between such side mirrors52and the obstacles54, it may be possible to set the width of patterned light40to be equal to or greater than the width Wb of the entire vehicle including the side mirrors52.

The patterned light40is emitted onto the road surface, while the side mirrors52of another vehicle56are located in the air. When the width of the patterned light40is set to be equal to or less than the width Wb of the entire vehicle50, it is difficult for the driver of the vehicle50to determine whether the side mirrors52of the other vehicle56are located inside the patterned light40. Therefore, the width of the patterned light40may be set to a width Wc=Wb+2×Wm, where the width of the entire vehicle50, Wb, is added to the maximum protrusion of the side mirrors52, Wm, on both left and right sides. The maximum protrusion Wm of the side mirrors52is prescribed by law. In Japan, the maximum protrusion Wm of each side mirror52is 250 mm. Therefore, the width of the patterned light40may be Wc, where 500 mm is added to the width Wb of the entire vehicle50. With this structure, the driver of the vehicle can more easily determine the risk of the vehicle50contacting the side mirror52of the other vehicle56.

When the width of the patterned light40is excessively large, the patterned light40comes to interfere with the obstacle54more than necessary. In this case, the driver of the vehicle is likely to misjudge the vehicle50as impassable even when the vehicle50can pass smoothly. Therefore, the width of the patterned light40may be equal to or less than 1.4 times or 1.2 times the width Wb of the entire vehicle50.

The reference length Lp of the patterned light40in the direction of travel Dtr is, for example, sufficiently long to avoid the obstacle54. Avoiding the obstacle54means that the vehicle50stops before contacting the obstacle54, or that the other vehicle56, which is the obstacle54, moves to a position where it stops or does not contact the vehicle50.

The reference pattern length Lp may be a predetermined fixed value or a variable value that varies depending on the situation. For example, the reference pattern length Lp may vary according to the vehicle speed Vv of the vehicle50. That is, the higher the vehicle speed Vv, the longer it takes for the vehicle50to come to a stop. Therefore, the higher the vehicle speed Vv, the longer the reference pattern length Lp may be. For example, the reference pattern length Lp may be a value obtained by multiplying the vehicle speed Vv by the time required for the vehicle50to stop.

The reference pattern length Lp may vary depending on the relative speed between the vehicle50and the obstacle54. For example, when there is another vehicle56oncoming as the obstacle54, the greater the relative speed between the vehicle50and the other vehicle56, the longer the reference pattern length Lp may be. The relative speed can be estimated, for example, from the change over time of the size of the other vehicle56captured in the target image.

Thus, by changing the reference pattern length Lp according to the vehicle speed Vv of the vehicle50or the relative speed thereof, the risk of contact between the vehicle50and the obstacle54can be more accurately determined.

In the description above, the patterned light40having a band shape has been described. However, the shape of the patterned light40may be changed when it represents the passing area of the vehicle50. For example, the patterned light40may be a frame shape indicating the perimeter of the passing area, as illustrated inFIG.10A. The patterned light40may also be line-shaped, as illustrated inFIG.10B, indicating both end points of the passing area in the width direction. The patterned light40may be emitted in a form that calls the attention of drivers and others. For example, the patterned light40may be in a color not used in common headlights, such as red, brown, or blue. In the case of emergency vehicles, the warning light is mounted on the roof, and the patterned light40may be of the same color as this warning light. The patterned light40may be emitted in a blinking pattern rather than continuously. Furthermore, the patterned light40may be emitted in an animated manner by continuously switching the range of illumination. For example, as illustrated inFIG.11, the shape of the patterned light40may be changed so that the length of the patterned light40changes over time.

Next, a reference example is briefly described. In the description above, the illumination controller30identifies the movable area Amv based on the detection result from the environmental sensor24, and emits the patterned light40within the movable area Amv. However, in the reference example, the illumination controller30emits the patterned light40haphazardly without specifying the movable area Amv. In this case, the length of the patterned light40is varied according to the vehicle speed Vv of the vehicle50or the relative speed between the vehicle50and the obstacle54.

The illumination controller30may emit the patterned light40in front of the vehicle50without determining the direction of movement Dmv of the vehicle50. In other words, the longitudinal direction of the patterned light40may always be parallel to the front-rear axis of the vehicle50.

Alternatively, the illumination controller30may identify the direction of movement Dmv of the vehicle50based on at least one of the steering angle Ar, the vehicle speed Vv, the turn signal Stn, and the navigation information Inv, and identify the patterned light40along the direction of movement Dmv. For example, when the turn signal Stn is not generated and the steering angle Ar is almost zero, the illumination controller30determines the front of the vehicle50as the direction of movement Dmv. When the turn signal Stn is not generated and the steering angle Ar is equal to or greater than a certain value, the illumination controller30determines that the vehicle50is traveling on a curved road, and calculates the direction of movement Dmv based on the steering angle Ar and the vehicle speed Vv. Furthermore, when the turn signal Stn is generated, the steering angle Ar is inclined at or above a certain level, and the vehicle speed Vv is equal to or less than the first reference value, the illumination controller30may also determine that the vehicle50is going to turn in the direction indicated by the turn signal Stn. Alternatively, the illumination controller30may identify the direction of movement Dmv of the vehicle50based on the travel route included in the navigation information Inv, and may emit the patterned light40along the direction of movement Dmv.

In any case, in the reference example, the presence or absence of obstacles54is not detected, and the patterned light40is emitted haphazardly. Therefore, in the reference example, the patterned light40may interfere with the obstacle54. By observing the interference between the patterned light40and the obstacle54, the driver can easily judge whether smooth driving is possible. When the patterned light40interferes with the obstacle54, the driver can prevent contact with the obstacle54by stopping or changing the direction of the vehicle50.

REFERENCE SIGNS LIST