JP7535225B2 - Headlight control device and headlight control method - Google Patents

Description

The present invention relates to a headlight control device and a headlight control method that control the brightness of headlights that can illuminate the area ahead of a vehicle traveling in a lane.

2. Description of the Related Art Conventionally, driving assistance systems that support a driver operating a vehicle, such as an adaptive front-lighting system (AFS), which controls the optical axis direction (illumination range) of headlights in accordance with the steering direction of the steering wheel and the driving environment, have been known.
It is also known that at night in the rain, the light emitted from the headlights of the vehicle is specularly reflected by water films on the road surface, and the light is diffusely reflected or retroreflected by the road surface, reducing the visibility of occupants, particularly the visibility of lane markings.

Several technologies have been proposed to improve occupant visibility when driving in bad weather.
The vehicle lighting system of Patent Document 1 comprises a first lighting unit, a second lighting unit for illuminating an area farther than the first lighting unit, a rotary drive unit capable of selectively switching the second lighting unit between a first illumination direction for normal weather and a second illumination direction for bad weather, and a control unit that controls the rotary drive unit, and the control unit controls the rotary drive unit based on weather conditions.
In the light distribution pattern for bad weather, the central region is set to have a lower illuminance than the side regions in order to suppress diffuse reflection of the irradiated light.

The human pupil is an ellipse that is close to a perfect circle and is formed in the hole of the eyeball surrounded by the iris. The pupil is controlled by the autonomic nervous system, and reacts by adjusting the diameter of the pupil mainly through the action of the pupil dilator muscle (mydriasis muscle) controlled by the sympathetic nervous system and the pupil sphincter muscle (miosis muscle) controlled by the parasympathetic nervous system.
Pupillary responses are classified into photoreactions, which respond to changes in the surrounding light such as lighting, and near-vision responses, which respond to the distance to the gazed object (point of gaze). In near-vision responses, the pupil constricts more as the distance to the gazed object becomes shorter. In addition to photoreactions to light stimuli and near-vision responses in response to the gazed object distance, the pupil also responds to sound stimuli and electrical or mechanical pain stimuli.

JP 2018-043666 A

The vehicle lighting system of Patent Document 1 can reduce light veiling glare caused by diffuse reflection of emitted light during rainy nighttime conditions, thereby improving the visibility of occupants.
However, while the technology of Patent Document 1 suppresses the diffuse reflection of illuminated light caused by raindrops or fog particles, it is unable to ensure a sufficient forward visibility distance for the boundary lines of the lane in which the vehicle is traveling, which may cause occupants to feel uneasy when driving.

When driving in bad weather, in addition to the light from the headlights of oncoming vehicles, ambient light from the surroundings is specularly reflected by the water film on the road surface and enters the eyes of the occupant in large quantities. The pupils constrict due to the reflex light reaction, and the light entering the retina is narrowed because it passes through the constricted pupil.
On the other hand, the reflected light (brightness) from the lane boundary line naturally decreases as it moves away from the lane boundary line in the forward direction.
Therefore, at night and in the rain, the driver may not be able to fully see the forward visibility information required for driving, that is, the lane boundary lines ahead in the traveling direction, both mentally and technically.
If a driver is unable to maintain the required visibility distance for the lane boundary line ahead while driving (hereinafter referred to as the required visibility distance), the driver will feel anxious both mentally and in terms of skills.

Also, in order to make the distance ahead of the boundary line visible to the occupant's eyes (hereinafter referred to as the visible distance) equal to or greater than the required visibility distance, it is conceivable to forcibly dilate the pupil diameter of the occupant.
However, it is physically difficult to develop a pupil dilation device that constantly forcibly dilates the pupil diameter, and the control of the device would be extremely complicated. Moreover, if the object being gazed upon by the occupant is located near the vehicle, the occupant's near vision response may be impaired, which may pose a safety problem.
That is, it is not easy to ensure the required forward visibility distance while minimizing the effect on pupil response.

The object of the present invention is to provide a headlight control device and a headlight control method that can ensure forward visibility while minimizing the effect on pupillary response.

The invention of claim 1 provides a headlight control device that controls the brightness of headlights that can illuminate the area ahead of a vehicle traveling in a lane, the headlight control device comprising: pupil diameter detection means for detecting the pupil diameter of a occupant driving the vehicle; vehicle speed detection means for detecting the traveling speed of the vehicle; visible distance detection means for detecting the visible distance ahead of the lane that can be seen by the occupant based on the detected pupil diameter using preset visual characteristics; required visibility distance detection means for detecting a required visibility distance ahead of the lane that is required for the occupant to drive the vehicle based on the detected vehicle speed; and headlight control means for controlling the headlights, wherein when the visible distance is shorter than the required visibility distance, the headlight control means controls the headlights so that the brightness of the portion of the lane boundary line that is closer to the vehicle than the brightness of the portion of the lane boundary line that is farther from the vehicle is increased so that the visible distance is equal to or greater than the required visibility distance.
It is characterized by the following.

This headlight control device has a pupil diameter detection means for detecting the pupil diameter of an occupant driving a vehicle, and a visible distance detection means for detecting the visible distance in the lane ahead that the occupant can see based on the detected pupil diameter using a preset visual characteristic, so that it is possible to detect the occupant's specific visible distance, which is the biological information of the driving occupant.It has a vehicle speed detection means for detecting the traveling speed of the vehicle, and a required visibility distance detection means for detecting the required visibility distance in the lane ahead that is required for the occupant to drive the vehicle based on the detected vehicle speed, so that it is possible to detect the occupant's specific required visibility distance, which is the actual occupant's state, via the vehicle speed.
When the visible distance is shorter than the required visibility distance, the headlight control means controls the headlights to increase the luminance of a portion of the lane boundary line close to the vehicle relative to the luminance of a portion of the lane boundary line farther from the vehicle so that the visible distance is equal to or greater than the required visibility distance . This makes it possible to dilate the pupils of the occupant as a light response using a glare illusion, and improve the visibility of the occupant using the pupil response, so that the visible distance of the occupant can be made equal to or greater than the required visibility distance by utilizing the light response while minimizing the effect on the pupil response.

The invention of claim 2, in the invention of claim 1, is characterized in that it has an imaging means for imaging lane boundary lines extending forward, and a luminance information creation means for image processing the imaging information of the lane boundary lines to create luminance information of the lane boundary lines, wherein the visual characteristics include a first characteristic in which the relationship between the luminance of the lane boundary lines and the visible distance is preset, and a second characteristic in which the relationship between the minimum luminance of the lane boundary lines and the pupil diameter is preset, and the visible distance detection means detects the visible distance using the first characteristic and the second characteristic.
With this configuration, the visible distance of the occupant can be detected with high accuracy using the brightness information of the actual boundary line, and the visible distance can be easily compared with the required visible distance using the first and second characteristics.

The invention of claim 3 is characterized in that, in the invention of claim 1 or 2, the required visibility distance detection means detects the required visibility distance using a third characteristic in which the relationship between vehicle speed and required visibility distance is preset.
According to this configuration, the required visibility distance can be detected by using the known third characteristic.

The invention of claim 4 is characterized in that in the invention of any one of claims 1 to 3 , the headlight control means executes control of the headlights except when the road surface is dry or when there is a curve closer than the required visibility distance.
According to this configuration, the headlight brightness can be controlled by adjusting visibility only when the lane boundary lines are visible, and the control execution period can be limited.

The invention of claim 5 is a headlight control method for controlling the brightness of headlights capable of illuminating the area ahead of a vehicle traveling in a lane, the method comprising: a pupil diameter detection step for detecting the pupil diameter of a occupant driving the vehicle; a vehicle speed detection step for detecting the traveling speed of the vehicle; a visible distance detection step for detecting a visible distance ahead of the lane that can be seen by the occupant based on the detected pupil diameter using a preset visibility distance characteristic; a required visibility distance detection step for detecting a required visibility distance ahead of the lane that is required for the occupant to drive the vehicle based on the detected vehicle speed; and a headlight control step for controlling the headlights, when the visible distance is shorter than the required visibility distance , to increase the brightness of a portion of the lane boundary line closer to the vehicle than the brightness of a portion of the lane boundary line farther from the vehicle so that the visible distance is equal to or greater than the required visibility distance.
According to this configuration, the same effect as that of the first aspect of the invention can be achieved.

The headlight control device and headlight control method of the present invention detect the occupant's specific visible distance via pupil diameter, making it possible to ensure forward visibility while minimizing the effect on pupil response.

1 is a schematic diagram of a vehicle equipped with a headlight controlled by a control device according to a first embodiment; FIG. 2 is a schematic diagram showing the configuration of a headlight. FIG. 2 is a schematic diagram showing an LED array. FIG. 2 is a block diagram showing the configuration of an ECU. 11 is a graph of a first characteristic showing the relationship between visible distance and boundary line luminance. 11 is a graph of a second characteristic showing the relationship between pupil diameter and boundary line minimum luminance. 13 is a table of a third characteristic showing the relationship between vehicle speed and required visibility distance. 5 is a flowchart showing a processing operation of headlight control. 13 is a flowchart showing a visibility determination process operation. 11A and 11B are diagrams showing verification results when verifying changes in pupil diameter of an occupant due to headlight control. 11A and 11B are diagrams showing verification results when verifying changes in the visible distance of an occupant due to headlight control. Graphs of the first characteristic for Example 2, where (a) is the first characteristic set using the luminance of two gaze points, and (b) is the first characteristic set using the luminance of one gaze point.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
The following description is an example in which the present invention is applied to vehicle headlight control, and is not intended to limit the present invention, its applications, or its uses.

A first embodiment of the present invention will be described below with reference to FIGS. 1 to 11. FIG.
1 shows a vehicle 1 having a pair of left and right headlights 4 controlled by a control device according to the first embodiment. The vehicle 1 is a four-wheeled vehicle, and two of the four wheels 2 that are symmetrically positioned on the left and right, for example, a pair of left and right front wheels, are driven by a drive unit (not shown). This allows the vehicle 1 to travel. In the following description, the front is the front side, the left side is the left side, and the upper side is the upper side as viewed from the driver driving the vehicle 1. The following description also includes an explanation of a headlight control method.

A pair of headlights 4 are provided at both the left and right ends of the front end of the vehicle 1, respectively, and illuminate the area in front of the vehicle 1. Although detailed illustration is omitted, each headlight 4 is disposed so as to be continuous with the front fender of the vehicle 1. These headlights 4 are electrically connected to the battery 3. The headlights 4 are turned on by power supplied from the battery 3.

As shown in FIG. 2, the headlight 4 is equipped with a low beam unit 5 and a high beam unit 6. The low beam unit 5 emits a low beam directed slightly downward in front of the vehicle. The low beam forms part of the light emitted by the headlight 4 that is irradiated near the vehicle body. The high beam unit 6 emits a high beam that is irradiated in a substantially horizontal direction in front of the vehicle. The high beam forms part of the light emitted by the headlight 4 that is irradiated farther from the vehicle body.

The low beam unit 5 has an LED array 5a consisting of a plurality of LED light sources 5b that emit a low beam, and a reflector arranged behind it. As shown in Fig. 3, the LED array 5a is formed by arranging a plurality of LED light sources 5b in a vertical direction, and arranging them in a plurality of rows in a horizontal direction (vehicle width direction). Each LED light source 5b is configured so that the brightness can be adjusted independently. The high beam unit 6 also has an LED array 6a consisting of a plurality of LED light sources 6b, similar to the low beam unit 5.
The arrangement of the LED light sources 6b in the LED array 6a may be the same as or different from the arrangement of the LED light sources 5b.

Next, the ECU 20 will be described.
As shown in Fig. 1, a body-system ECU (Electrical Control Unit) 20 is configured to be able to control the brightness of the light emitted by the headlights 4 so as to improve the visibility of a driver while the headlights 4 are on. Here, visibility generally means the degree of intensity at which the human eye perceives light for each wavelength. In this embodiment, the subject of the present invention is photopic luminosity, which is the degree of brightness (luminance) of lane boundaries ahead in the traveling direction that can be seen by a driver.

The ECU 20 is computer hardware that is composed of a processor and a memory having multiple modules. In addition to controlling the headlights 4, the ECU 20 is configured to be able to control body-related devices such as door lock mechanisms and power window devices.

As shown in FIG. 4, the ECU 20 generates a control command signal for the headlights 4 based on information input from a plurality of sensors.
These multiple sensors include an in-vehicle camera 11 (pupil diameter detection means), multiple exterior cameras 12, a headlight switch 13, a vehicle speed sensor 14 (vehicle speed detection means) capable of detecting the traveling speed of the vehicle 1, and a GPS (Global Positioning System) sensor 15 capable of receiving the current position information of the vehicle 1 and surrounding geographical information, etc. from an external server.

The in-vehicle camera 11 is disposed so as to capture an image of the face, including the eyes, of an occupant seated in the driver's seat. A plurality of exterior cameras 12 are disposed so as to capture an image of the surroundings of the vehicle 1 in a 360° horizontal direction. The cameras 11 and 12 are, for example, image sensors such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor).
The headlight switch 13 is provided, for example, on a winker lever. When the headlight switch 13 is turned on, a headlight control unit 25 (described later) is activated, and light is emitted from the headlights 4 to the front of the vehicle 1.

As shown in Figure 4, the ECU 20 includes a driving scene determination unit 21 that determines the driving scene of the vehicle 1, a memory unit 22, a visible distance detection unit 23 (visible distance detection means) that detects the visible distance Dp, a required visible distance detection unit 24 (required visible distance detection means) that detects the required visible distance Dr, and a headlight control unit 25 (headlight control means).
The ECU 20 processes the occupant images captured by the in-vehicle camera 11 and the vehicle exterior environment images captured by the multiple exterior cameras 12. The ECU 20 sequentially detects the pupil diameters of the occupants in a time series manner based on the processed occupant images. The ECU 20 can process the image information of the lane boundary lines from a position near the front of the vehicle 1 to the front in the traveling direction to generate luminance information of the lane boundary lines.

First, the driving scene determination unit 21 will be described.
The driving scene determination unit 21 identifies the driving time period (daytime, nighttime) in which the vehicle 1 is driving, the current driving position (straight road, intersection, urban area, suburban area), weather (sunny, rainy, cloudy, snowy), road conditions (wet road surface, snowy), and the surrounding environment (presence or absence of ambient light from stores, street lights, etc.) based on the exterior environment information captured by multiple exterior cameras 12.
The driving scene determination unit 21 determines whether the vehicle 1 is traveling or not based on the vehicle speed detected by the vehicle speed sensor 14. The driving scene determination unit 21 also determines whether a curve is present closer to the vehicle than a required visibility distance Dr (described later) based on the vehicle exterior environment information captured by the multiple exterior cameras 12 and the GPS sensor 15.

Next, the storage unit 22 will be described.
The storage unit 22 stores the three first to third characteristics F1 to F3.
As shown in Fig. 5, the first characteristic F1 is a preset relationship between the visible distance Dp of an occupant and the luminance of the lane boundary line visible to the occupant. The first characteristic F1 is expressed as a graph similar to a hyperbolic function. Therefore, the luminance of the light reflected from the boundary line decreases as the visible distance Dp increases. The first and second characteristics F1 and F2 correspond to the visual characteristics of the present invention.

6, the second characteristic F2 is a preset relationship between the pupil diameter of the occupant and the minimum luminance of the lane boundary line that the occupant can see. The second characteristic F2 is expressed as a graph similar to a hyperbolic function, and as the pupil diameter increases, the amount of light incident on the retina (the amount of light reflected from the boundary line) increases, so that the occupant can recognize the reflected light even if the luminance of the reflected light is low.
Therefore, when the pupil diameter is large, the occupant can see the boundary line even if it has low brightness.

As shown in Fig. 7, the third characteristic F3 is a preset relationship between the traveling speed of the vehicle 1 and the required visibility distance Dr. The third characteristic F3 can be expressed as a table equivalent to a linear function, and the required visibility distance Dr increases as the vehicle speed increases. The required visibility distance Dr is defined as a forward visibility information area that is mentally and technically required for the occupant to drive.
As a driver characteristic while driving, the occupant has a tendency to focus on a destination point three seconds ahead as a point where danger can be avoided by steering or sudden braking. In this embodiment, the driver characteristic is taken into consideration and the distance from the current position to the destination point three seconds ahead is set as the required visual distance Dr.

Next, the visible distance detection unit 23 will be described.
The visible distance detection unit 23 calculates the visible distance Dp using the pupil diameter of the occupant detected during driving and the first and second characteristics F1 and F2. Specifically, the visible distance detection unit 23 detects the minimum luminance B1 of the lane boundary line that the occupant can see using the pupil diameter R1 of the occupant obtained from the image information captured by the in-vehicle camera 11 and the second characteristic F2 (see FIG. 6). If the luminance of the lane boundary line is B1 or more, the lane boundary line with the pupil diameter R1 can be visually recognized by the occupant.

As shown in FIG. 5, the visible distance detection unit 23 uses the first characteristic F1 and the boundary line minimum luminance B1 calculated from the second characteristic F2 to detect the visible distance Dp (Dp1) of the boundary line ahead that can be seen by the occupant. That is, an occupant with a pupil diameter R1 can only see lane boundary lines with a luminance of B1 or more due to the light receiving capacity of the retina. Therefore, lane boundary lines in an area farther away than the visible distance Dp1, where the luminance is less than B1, cannot be seen due to their visual ability.

Next, the necessary visibility distance detection unit 24 will be described.
The required visibility distance detection unit 24 calculates the required visibility distance Dr by using the vehicle speed and the third characteristic F3. Specifically, as shown in Fig. 7, the required visibility distance detection unit 24 detects the required visibility distance Dr (Dr1) at which the occupant does not feel uneasy by using the vehicle speed detected by the vehicle speed sensor 14 and the third characteristic F3. For example, when the speed is 60 km/h, the required visibility distance Dr1 is 50 m.

Next, the headlight control unit 25 will be described.
The headlight control unit 25 is configured to be able to execute visibility increase control for the light emitted by the headlight 4. The visibility of the occupant can be adjusted by a glare illusion, specifically, a luminance gradient that is the difference between the luminance of a portion far from the vehicle and the luminance of a portion near the vehicle.
When the visibility is improved, the luminance of the portion near the vehicle is increased and the luminance of the portion far from the vehicle is decreased, whereas when the visibility is decreased, the luminance of the portion far from the vehicle is increased and the luminance of the portion near the vehicle is decreased.

The headlight control unit 25 adjusts the luminance gradient tendency of the light emitted by the headlight 4 by adjusting the luminance of each of the LED light sources 5b, 6b that constitute the headlight 4. For example, the headlight control unit 25 adjusts the luminance gradient tendency of the headlight 4 by making the luminance of the LED light source 5b of the low beam unit 5, which irradiates light onto the portion near the vehicle, higher than the luminance of the LED light source 6b of the high beam unit 6, which irradiates light onto the portion farther from the vehicle.

The headlight control unit 25 is configured to execute visibility increasing control when it is necessary to improve the visibility of the occupant. When the visible distance Dp is shorter than the required visibility distance Dr, the headlight control unit 25 determines that the visibility of the occupant needs to be improved.
Furthermore, even if it is determined that visibility improvement is necessary, the headlight control unit 25 prohibits visibility increase control if there is a possibility of adversely affecting the near vision reaction of the occupant, for example, due to poor physical condition or an increase in boundary luminance exceeding 0.2 (cd/ ^m2 ).

Specifically, when the vehicle 1 is traveling at 60 km/h at night in the rain, the required visibility distance Dr1 is 50 m (see FIG. 7). At this time, the occupant's pupil diameter R1 is, for example, 2.7 mm, and the boundary line minimum luminance B1 is, for example, 0.2 as shown in FIG. 6. When the boundary line minimum luminance B1 is 0.2, the visible distance Dp1 is, for example, 45 m as shown in FIG. 5. If the visible distance Dp1 is smaller than the required visibility distance Dr1 (50 m), the occupant will not be able to see the boundary line 50 m ahead, which will cause mental and technical anxiety.

As shown in Figure 5, by changing the visibility level of the occupant from boundary luminance B1 to B2, the occupant becomes able to see the boundary line 50 m ahead. Changing the boundary line luminance from B1 to B2 is equivalent to changing the boundary line minimum luminance from B1 to B2, so as shown in Figure 6, the glare illusion is used to dilate the occupant's pupil diameter to 3.0 mm, improving the occupant's visual ability and eliminating the occupant's sense of anxiety.

Next, an example of the processing operation of headlight control by the ECU 20 will be described with reference to the flowchart shown in FIG. 8. In the figure, Si (i=1, 2, ...) indicates each step.

First, information input from each sensor such as the interior and exterior cameras 11, 12 is read (S1), and the process proceeds to S2. In S2, it is determined whether or not a request to turn on the headlights 4 has been made by an occupant.
If the result of the determination in S2 is that the headlight switch 13 has been turned on and a request to turn on the lights is made, the environment outside the vehicle is dark, so the process proceeds to S3. If the result of the determination in S2 is that the headlight switch 13 has not been turned on and there has been no request to turn on the lights, the environment outside the vehicle is bright, and the scene does not require visibility increase control, so the process returns.

In S3, it is determined whether the vehicle 1 is currently traveling.
If the result of the determination in S3 is that the vehicle 1 is moving, the process proceeds to S4.
If the result of the determination in S3 is that the vehicle 1 is not moving, the process proceeds to S7.
In S4, a visibility determination process is executed to determine whether or not the current scene requires improvement in visibility, and the process proceeds to S5.

In S5, it is determined whether or not visibility increasing control should be executed.
Even if it is necessary to improve the visibility of the occupant, in a situation where there is a possibility of adversely affecting the occupant's near vision reaction, the visibility increasing control is prohibited, but other visibility improving controls can be executed.
If it is determined in S5 that visibility increasing control is to be executed, the process proceeds to S6, in which the headlights 4 are used to increase the luminance in the vicinity of the vehicle in order to increase the visibility, and then the process returns.
If the result of the determination in S5 is that visibility increase control is not to be executed, the process proceeds to S7. In S7, the visibility is not to be increased, so the current luminance of the headlights 4 is maintained, and the process returns.

Next, an example of the visibility determination process executed in S4 will be described with reference to the flowchart shown in FIG. 9. In the figure, Si (i=11, 12, ...) indicates each step.

In S4, the required visibility distance Dr corresponding to the detected vehicle speed is first calculated using the third characteristic F3 (S11), and the process proceeds to S12. In S12, the pupil diameter of the occupant is detected based on the captured image of the occupant, and the visibility distance Dp is calculated based on the detected pupil diameter and boundary luminance (minimum boundary luminance), and the process proceeds to S13.

In S13, it is determined whether the road surface of the lane is wet.
If the road surface is wet as a result of the determination in S13, the light emitted by the headlights 4, the ambient light, etc. are reflected by the water film, so the process proceeds to S14. If the road surface is not wet as a result of the determination in S13, the light emitted by the headlights 4, the ambient light, etc. are not reflected by the water film, so the process proceeds to S17.

In S14, it is determined whether or not there is a curve closer than the required visibility distance Dr.
If the determination in S14 shows that there is no curve closer than the required visibility distance Dr, and visibility is good, the occupant can see the area ahead of the required visibility distance Dr, so the process proceeds to S15.
If the result of the determination in S14 is that there is a curve closer than the required visibility distance Dr, even if visibility is good, it is physically difficult for the occupant to see the area ahead of the curve, so the process proceeds to S17.

In S15, it is determined whether the visible distance Dp is smaller than the necessary visible distance Dr.
If the result of the determination in S15 is that the visible distance Dp is smaller than the required visibility distance Dr, it is determined that visibility improvement is necessary because the visible distance Dp needs to be extended to the required visibility distance Dr (S16), and the process ends. If the result of the determination in S15 is that the visible distance Dp is equal to or greater than the required visibility distance Dr, it is determined that visibility improvement is unnecessary because the visible distance Dp exceeds the required visibility distance Dr (S17), and the process ends.

Next, the operation and effect of the headlight control device according to the embodiment of the present invention will be described.
To explain the operation and effect, actual vehicles A and B were prepared, and verification experiments were performed on the pupil diameter and visible distance of the occupants. Actual vehicle A is a vehicle that does not execute visibility increase control, and actual vehicle B is a vehicle that executes visibility increase control, and the number n is 3. In addition, with the exception of whether or not visibility increase control is executed, various conditions such as the luminance of lane boundary lines, ambient light, and vehicle speed (60 km/h) were set to the same values.

The verification results will be described with reference to FIG. 10 and FIG.
As shown in Figure 10, it was found that the pupil diameter of the occupant in vehicle B was 0.33 mm larger than that of the occupant in vehicle A. This confirmed that the glare illusion caused a pupil reaction (mydriasis) in the occupant's eyes.
As shown in Fig. 11, it was found that the visible distance Dp of the occupant in vehicle B was 5 m longer than the visible distance Dp of the occupant in vehicle A. This confirmed that the larger the pupil diameter, the more light is incident on the retina, and the longer the visible distance Dp.

This headlight control device has an in-vehicle camera 11 that detects the pupil diameter of the occupant driving the vehicle 1, and a visible distance detection unit 23 that detects the visible distance Dp of the lane ahead that the occupant can see based on the pupil diameter of the occupant detected using preset visual characteristics (first and second characteristics F1 and F2), so that it can detect the occupant-specific visible distance Dp, which is the biological information of the driving occupant. Since it has a vehicle speed sensor 14 that detects the traveling speed of the vehicle 1, and a required visibility distance detection unit 24 that detects the required visibility distance Dr of the lane ahead that is necessary for the occupant to drive the vehicle 1 based on the detected vehicle speed, it can detect the required visibility distance Dr of the occupant, which is the actual occupant state, via the vehicle speed. When the visible distance Dp is smaller than the required visibility distance Dr, the headlight control unit 25 controls the headlights 4 so that the visible distance Dp is equal to or greater than the required visibility distance Dr. At this time, the headlight control unit 25 controls the headlights 4 so as to increase the luminance of the portion of the lane boundary line that is closer to the vehicle 1 than the luminance of the portion of the lane boundary line that is farther from the vehicle 1. This makes it possible to dilate the pupils of the occupant as a light reaction using the glare illusion, and to improve the visibility of the occupant using the pupil reaction, so that the visible distance Dp of the occupant can be made equal to or greater than the required visibility distance Dr by utilizing the light reaction while minimizing the effect on the pupil reaction.

The required visibility distance detection unit 24 detects the required visibility distance Dr using a third characteristic F3 in which the relationship between the vehicle speed and the required visibility distance Dr is preset, and therefore can detect the required visibility distance Dr using the known third characteristic F3.

The headlight control unit 25 executes control of the headlights 4 except when the road surface is dry or when there is a curve closer than the required visibility distance Dr, and therefore can control the brightness of the headlights 4 only when the lane boundaries are visible by adjusting visibility, and can limit the period during which control is executed.

The headlight control method controls the luminance of headlights 4 capable of illuminating the area ahead of a vehicle traveling in a lane, the method comprising: a pupil diameter detection step (S1) of detecting the pupil diameter of an occupant driving the vehicle 1; a vehicle speed detection step (S1) of detecting the traveling speed of the vehicle; a visible distance detection step (S12) of detecting a visible distance Dp ahead of the lane that is visible to the occupant based on the detected pupil diameter using preset visibility distance characteristics (first and second characteristics F1, F2); a required visibility distance detection step (S11) of detecting a required visibility distance Dr ahead of the lane that is required for the occupant to drive the vehicle based on the detected vehicle speed; and a headlight control step (S6) of controlling the headlights 4 so that, when the visible distance Dp is smaller than the required visibility distance Dr , the luminance of a portion of the lane boundary line closer to the vehicle 1 is increased relative to the luminance of a portion of the lane boundary line farther from the vehicle 1 so that the visible distance Dp becomes equal to or greater than the required visibility distance Dr. This allows the glare illusion to be used to dilate the occupant's pupils as a light reaction, and the occupant's visual sensitivity can be improved using the pupillary reaction, thereby ensuring forward visibility while minimizing the impact on the pupillary reaction.

Next, a headlight control device according to a second embodiment will be described with reference to Fig. 12(a) and Fig. 12(b). In the first embodiment, the first characteristic F1 is a relationship between the visible distance Dp of the occupant and the luminance of the lane boundary line visible to the occupant, which is preset, whereas in the second embodiment, the first characteristic F1a is set using luminance information of the boundary line that is actually measured.
The same members as those in the first embodiment are denoted by the same reference numerals.

The ECU 20 processes the images of the occupants captured by the in-vehicle camera 11 and the images of the external environment captured by the multiple external cameras 12. The ECU 20 sequentially detects the pupil diameter of the occupants in a time series manner based on the processed occupant images. The ECU 20 processes the image information of the lane boundary lines from a position near the front of the vehicle 1 forward in the direction of travel to create brightness information of the lane boundary lines.

The direction of the occupant's gaze is calculated based on a combination of the direction of the occupant's face and the direction of the pupils, the points (gazing points) where the gaze direction intersects with the lane are determined, and the brightness of the boundary lines at at least two of the gaze points located furthest forward among the gaze points is detected.
12A, a hyperbola passing through at least two gaze points P1 and P2 is created and set as a first characteristic F1a. The visible distance detection unit 23 detects a visible distance Dp of the boundary line ahead of the lane that can be seen by the occupant using the boundary line minimum luminance B1 obtained from the second characteristic F2 and the first characteristic F1a.

The above-mentioned first characteristic F1a requires the luminance of the boundary line at two gaze points, but it is also possible to set the first characteristic F1b with the luminance of the boundary line at one gaze point.
As shown in Fig. 12(b), a standard hyperbola L is set in advance, and the luminance of the boundary line at the gaze point P3 located at the frontmost position is detected. The standard hyperbola L is shifted so as to pass through the gaze point P3 to set a first characteristic F1b. This makes it possible to detect the visible distance Dp of the occupant with high accuracy using the luminance information of the boundary line that is actually measured, and makes it possible to easily compare the visible distance Dp with the required visible distance Dr using the first characteristic F1a (F1b) and the second characteristic F2.

Next, a modified example in which the above embodiment is partially changed will be described.
1) In the above embodiment, the luminance of the LED light source 5b of the low beam unit 5 that irradiates the near side of the vehicle is set higher than the luminance of the LED light source 6b of the high beam unit 6 that irradiates the far side of the vehicle, but the luminance of the illumination in the occupant's field of vision may be made constant before and after the control. Specifically, the luminance of the LED light source 5b of the low beam unit 5 that irradiates the near side of the vehicle is increased and the luminance of the LED light source 6b of the high beam unit 6 that irradiates the far side of the vehicle is decreased, so that the sum of the luminance of the near side of the vehicle and the luminance of the far side of the vehicle is made constant before and after the control. This makes it possible to reduce the energy consumption of the headlight 4.

2) In the above embodiment, an example was described in which the pupil diameter was dilated by utilizing a glare illusion. However, in order to further enhance the pupil dilation effect, it is also possible to use other media in addition to the light stimulus.
For example, a sound stimulus may be suddenly applied in parallel with headlight control, or a change in lighting color may also cause pupil dilation as a pupil response.

3) In the above embodiment, an example was described in which the graph of the first characteristic F1 and the graph of the second characteristic F2 were stored as independent two-dimensional graphs, but they may also be stored in advance as a single three-dimensional graph with pupil diameter, boundary line luminance, and visible distance Dp as the three axes.
In addition, the first characteristic F1 and the second characteristic F2 may be stored in the form of a table rather than a graph, and the third characteristic F3 may be stored in the form of a graph of a linear function rather than a table.

4) In addition, a person skilled in the art can implement the above-mentioned embodiments in various modified forms without departing from the spirit of the present invention, and the present invention also includes such modified forms.

1 Vehicle 4 Headlight 11 In-vehicle camera 12 Out-vehicle camera 20 ECU
23 Visible distance detection unit 24 Required visibility distance detection unit 25 Headlight control units F1, F1a, F1b First characteristic F2 Second characteristic F3 Third characteristic

Claims (5)

A headlight control device controls the brightness of a headlight capable of illuminating a front area of a vehicle traveling along a lane,
A pupil diameter detection means for detecting a pupil diameter of a vehicle occupant who drives the vehicle;
A vehicle speed detection means for detecting a traveling speed of a vehicle;
a visible distance detection means for detecting a visible distance ahead of the lane that can be seen by an occupant based on the detected pupil diameter by using a preset visual characteristic;
a required visibility distance detection means for detecting a required visibility distance in a lane ahead required for a driver to drive the vehicle based on the detected vehicle speed;
A headlight control means for controlling the headlights,
The headlight control device is characterized in that, when the visible distance is shorter than the required visibility distance, the headlight control means controls the headlights so that the brightness of the portion of the lane boundary line closer to the vehicle is higher than the brightness of the portion of the lane boundary line farther from the vehicle, so that the visible distance is equal to or greater than the required visibility distance. An imaging means for imaging a lane boundary line extending ahead;
a luminance information generating means for generating luminance information of the lane boundary line by image processing of the image information of the lane boundary line,
the visual characteristic includes a first characteristic, which is a preset relationship between a luminance of a lane boundary line and a visible distance, and a second characteristic, which is a preset relationship between a minimum luminance of a lane boundary line and a pupil diameter,
2. The headlight control device according to claim 1, wherein the visible distance detection means detects the visible distance by using the first characteristic and the second characteristic. The headlight control device according to claim 1 or 2, characterized in that the necessary visibility distance detection means detects the necessary visibility distance using a third characteristic in which the relationship between vehicle speed and necessary visibility distance is preset. The headlight control device according to any one of claims 1 to 3, characterized in that the headlight control means executes control of the headlights except when the road surface is dry or when there is a curve closer than the required visibility distance. A headlight control method for controlling the brightness of headlights capable of illuminating a front area of a vehicle traveling in a lane, comprising:
A pupil diameter detection step of detecting a pupil diameter of a vehicle occupant who drives the vehicle;
a vehicle speed detection step of detecting a traveling speed of a vehicle;
a visible distance detection step of detecting a visible distance ahead of the lane that can be seen by an occupant based on the detected pupil diameter by using a preset visible distance characteristic;
a required visibility distance detection step of detecting a required visibility distance in a lane ahead that is required for an occupant to drive the vehicle based on the detected vehicle speed;
a headlight control process for controlling the headlights when the visible distance is shorter than the required visibility distance, so that the visible distance becomes equal to or longer than the required visibility distance, by increasing the luminance of a portion of the lane boundary line closer to the vehicle than the luminance of a portion of the lane boundary line farther from the vehicle;
A headlight control method comprising the steps of: