CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2020-103713 filed on Jun. 16, 2020, incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a headlamp control device.

2. Description of Related Art

A headlamp control device in which headlamps are automatically turned on when illuminance is low in front of a subject vehicle and automatically turned off when the illuminance is high in front of the subject vehicle is well-known. According to this device, the headlamps are turned on when the subject vehicle enters a tunnel and turned off when the subject vehicle leaves the tunnel during the daytime. However, tunnels may be built so as to be close to each other. In such a case, the headlamps are turned off each time the vehicle leaves a tunnel, and turned on each time the vehicle enters another tunnel. That is, the headlamps are repeatedly turned on and off at short intervals. Consequently, it is highly likely that a driver of the subject vehicle may be inconvenienced.

A headlamp control device configured to address such shortcomings has been suggested (see, for example, Japanese Unexamined Patent Application Publication No. 2009-262579). When the illuminance in front of the subject vehicle is equal to or higher than a predetermined illuminance while the headlamps are turned on, the device keeps the headlamp turned on without turning them off and stores the illuminance at that time. The device turns off the headlamps if the illuminance in front of the subject vehicle becomes higher than the stored illuminance after a certain period of time, and otherwise keeps the headlamps turned on. Further, the device turns off the headlamps if the illuminance in front of the subject vehicle is equal to or higher than a predetermined illuminance after a certain period of time, and otherwise keeps the headlamps turned on.

With this device, even if the illuminance in front of the subject vehicle is equal to or higher than the predetermined illuminance when the vehicle leaves the tunnel, the headlamps are kept on without being turned off. If a next tunnel is located near the tunnel, the subject vehicle will approach the next tunnel in a relatively short period of time. Consequently, when the subject vehicle reaches or enters the next tunnel, the illuminance in front of the subject vehicle is equal to or higher than the predetermined illuminance and the certain period of time has not elapsed. Therefore, when the certain period of time elapses, the illuminance in front of the subject vehicle has not increased above the stored illuminance, and the headlamps are kept turned on. If the vehicle is traveling in the next tunnel when the certain period of time has further elapsed, the headlamps remain turned on because the illuminance in front of the subject vehicle is lower than the predetermined illuminance. As stated above, the device is intended to prevent the headlamps from being repeatedly turned on and off at short intervals.

SUMMARY

With a conventional headlamp control device, depending on a length of the certain period of time, the subject vehicle may enter the next tunnel immediately after the headlamps are tunnel off and then the headlamps may be turned on again. In this case, the headlamps are turned on and off in a short period of time, which may cause the driver to be inconvenienced.

Furthermore, the conventional headlamp control device controls the headlamps such that they are automatically turned on and off during the daytime, but it is desirable that the driver is not inconvenienced even when the headlamps are automatically turned on and off at nighttime.

The present disclosure provides a headlamp control device that automatically controls an ON state and OFF state of headlamps such that the driver is not inconvenienced during the daytime as well as at nighttime.

According to a first aspect of the present disclosure, a headlamp control device includes an illuminance detection device that detects an ambient illuminance which is an illuminance around a subject vehicle, and a control unit configured to execute headlamp control for automatically switching a state of a headlamp of the subject vehicle between an ON state where the headlamp is turned on and an OFF state where the headlamp is turned off, and automatically switching the state of the headlamp between a high-beam state where a headlight angle of the headlamp is set to a high-beam angle and a low-beam state where the headlight angle is set to a low-beam angle.

The control unit switches, in a case where the ambient illuminance is equal to or lower than a predetermined on and off illuminance, switch the headlamp state from the OFF state to the ON state, and switches, in a case where the ambient illuminance is higher than the predetermined on and off illuminance, the headlamp state from the ON state to the OFF state.

The control unit estimates, in a case where the ambient illuminance is equal to or lower than a predetermined switching illuminance when the headlamp state is the ON state, a time required for the subject vehicle to travel to an entrance of a tunnel in front of the subject vehicle, as a first time, switches, in a case where the first time is longer than a first determination time, the headlamp state from the low-beam state to the high-beam state, and, keeps, in a case where the first time is equal to or shorter than the first determination time, the headlamp state as the low-beam state.

For example, in a case where the vehicle travels on a road where two tunnels are built close to each other at nighttime, a lamp state (that is a headlamp state) is automatically switched between the low-beam state and the high-beam state depending on brightness around the vehicle. Since it is brighter inside the tunnel than outside the tunnel, the lamp state is set to be the low-beam state inside a first tunnel, is switched from the low-beam state to the high-beam state when the vehicle leaves the first tunnel, and then is switched from the high-beam state to the low-beam state when the vehicle enters a second tunnel. In other words, the lamp state is switched twice. If a distance is short between the two tunnels and a relatively short time is required for the vehicle to leave the first tunnel and enter the second tunnel, the lamp state is switched twice in a short period of time. In such a case, a driver of the vehicle may be inconvenienced.

With the headlamp control device of the present disclosure, when the subject vehicle leaves the first tunnel and it is dark around the subject vehicle (when the ambient illuminance is equal to or lower than the predetermined switching illuminance), and in a case where the time required for the subject vehicle to travel to the entrance of the second tunnel is short (in a case where the first time is equal to or shorter than the first determination time), the lamp state is kept as the low-beam state. Therefore, even if the subject vehicle enters the second tunnel and it is bright around the subject vehicle (even if the ambient illuminance is higher than the predetermined switching illuminance), the lamp state is kept in the low-beam state. Accordingly, the lamp state is not switched twice in a short period of time. Consequently, it is possible to prevent the driver of the vehicle from being inconvenienced.

In the headlamp control device according to the first aspect of the present disclosure, the control unit may be configured to, in a case where the ambient illuminance is higher than the predetermined switching illuminance when the headlamp state is the ON state, estimate a time required for the subject vehicle to travel to the entrance of the tunnel in front of the subject vehicle, as a second time. The control unit may switch, in a case where the second time is longer than a second determination time, the headlamp state from the high-beam state to the low-beam state, and keep, in a case where the second time is equal to or shorter than the second determination time, the headlamp state as the high-beam state.

For example, when it is dim in the evening, it may be brighter outside the tunnel than inside the tunnel. At this time, when the vehicle travels on a road where two tunnels are built close to each other at nighttime, the lamp state is automatically switched between the low-beam state and the high-beam state depending on the brightness around the vehicle. The lamp state is set to be the high-beam state inside the first tunnel, is switched from the high-beam state to the low-beam state when the vehicle leaves the first tunnel, and then is switched from the low-beam state to the high-beam state when the vehicle enters a second tunnel. In other words, the lamp state is switched twice. If a distance is short between the two tunnels and a relatively short time is required for the vehicle to leave the first tunnel and enter the second tunnel, the lamp state is switched twice in a short period of time. In such a case, a driver of the vehicle may be inconvenienced.

With the headlamp control device of the present disclosure, when the subject vehicle leaves the first tunnel and it is bright around the subject vehicle (when the ambient illuminance is higher than the predetermined switching illuminance), and in a case where the time required for the subject vehicle to travel to the entrance of the second tunnel is short (in a case where the second time is equal to or shorter than the second determination time), the lamp state is kept in the high-beam state. Therefore, even if the subject vehicle enters the second tunnel and it is dark around the subject vehicle (even if the ambient illuminance is equal or lower than the predetermined switching illuminance), the lamp state is kept in the high-beam state. Accordingly, the lamp state is not switched twice in a short period of time. Consequently, it is possible to prevent the driver of the vehicle from being inconvenienced.

According to a second aspect of the present disclosure, a headlamp control device includes an illuminance detection device that detects illuminance around a subject vehicle as an ambient illuminance, and detects illuminance in a tunnel in front of the subject vehicle as a tunnel illuminance, and a control unit configured to execute headlamp control for automatically switching a state of a headlamp of the subject vehicle between an ON state where the headlamp is turned on and an OFF state where the headlamp is turned off, and automatically switching the state of the headlamp between a high-beam state where a headlight angle of the headlamp is set to a high-beam angle and a low-beam state where the headlight angle is set to a low-beam angle,

The control unit switches, in a case where the ambient illuminance is equal to or lower than a predetermined on and off illuminance, the headlamp state from the OFF state to the ON state, and switches, in a case where the ambient illuminance is higher than the predetermined on and off illuminance, the headlamp state from the ON state to the OFF state.

Furthermore, the control unit estimates, in a case where the ambient illuminance is equal to or lower than a predetermined switching illuminance when the headlamp state is the ON state, a time required for the subject vehicle to travel to an entrance of the tunnel in front of the subject vehicle, as a first time, switches, in a case where the first time is longer than a first determination time, the headlamp state from the low-beam state to the high-beam state, switches, in a case where the first time is equal to or shorter than the first determination time and the tunnel illuminance is equal to or lower than the predetermined switching illuminance, the headlamp state from the low-beam state to the high-beam state, and keeps, in a case where the first time is equal to or shorter than the first determination time and the tunnel illuminance is higher than the predetermined switching illuminance, the headlamp state as the low-beam state.

For example, when two tunnels are built close to each other, it may be dark inside the second tunnel and thus the high-beam state may be desirable in the second tunnel. In a case where the time required for the vehicle to leave the first tunnel and enter the second tunnel is short, the lamp state is set to be the low-beam state regardless of the brightness inside the second tunnel. Consequently, if the lamp state is set to the low-beam state inside the first tunnel, the low-beam state is kept when the vehicle leaves the first tunnel, and then is switched from the low-beam state to the high-beam state when the vehicle enters the second tunnel. In this case, the lamp state is switched only once, but the driver has to drive the vehicle in the low-beam state during a period between leaving the first tunnel and entering the second tunnel.

With the headlamp control device of the present disclosure, when the subject vehicle leaves the first tunnel and it is bright around the subject vehicle (when the ambient illuminance is higher than the predetermined switching illuminance), and in a case where the time required for the subject vehicle to travel to the entrance of the second tunnel is short (the first time is equal to or shorter than the first determination time) and it is dark inside the second tunnel (the tunnel illuminance is equal to or lower than the predetermined switching illuminance), the lamp state is switched from the low-beam state to the high-beam state. Consequently, the driver can drive the subject vehicle in the high-beam state during the period between leaving the first tunnel and entering the second tunnel. In this case, if the subject vehicle leaves the first tunnel and then enters the second tunnel, the lamp state is switched only once.

In the headlamp control device according to the second aspect of the present disclosure, the control unit may be configured to, in a case where the ambient illuminance is higher than the predetermined switching illuminance when the headlamp state is the ON state, estimate a time required for the subject vehicle to travel to the entrance of the tunnel in front of the subject vehicle, as a second time. The control unit may switch, in a case where the second time is longer than the second determination time, the headlamp state from the high-beam state to the low-beam state, keep in a case where the second time is equal to or shorter than the second determination time and the tunnel illuminance is equal to or lower than the predetermined switching illuminance, the headlamp state as the high-beam state, and switch, in a case where the second time is equal to or shorter than the second determination time and the tunnel illuminance is higher than the predetermined switching illuminance, the headlamp state from the high-beam state to the low-beam state.

For example, when two tunnels are built close to each other, it may be dark inside the second tunnel and thus the high-beam state may be desirable in the second tunnel. In a case where the time required for the vehicle to leave the first tunnel and enter the second tunnel is short, the lamp state is set to be the low-beam state regardless of the brightness inside the second tunnel. Consequently, if the lamp state is set to the high-beam state inside the first tunnel, the lamp state is switched from the high-beam state to the low-beam state when the vehicle leaves the first tunnel, and then is switched from the low-beam state to the high-beam state when the vehicle enters the second tunnel. Accordingly, the lamp state is switched twice in a short time. Further, the driver has to drive the subject vehicle in the low-beam state during the period between leaving the first tunnel and entering the second tunnel.

With the headlamp control device of the present disclosure, when the subject vehicle leaves the first tunnel and it is bright around the subject vehicle (when the ambient illuminance is higher than the predetermined switching illuminance), and in a case where the time required for the subject vehicle to travel to the entrance of the second tunnel is short (the second time is equal to or shorter than the second determination time) and it is dark inside the second tunnel (the tunnel illuminance is equal to or lower than the predetermined switching illuminance), the lamp state is kept as the high-beam state. Therefore, even if the subject vehicle leaves the first tunnel and then enters the second tunnel in a short period of time, the lamp state is not switched. Consequently, it is possible to prevent the driver of the vehicle from being inconvenienced. Moreover, the driver can drive the subject vehicle in the high-beam state during the period between leaving the first tunnel and entering the second tunnel.

According to a third aspect of the present disclosure, a headlamp control device includes an illuminance detection device that detects an ambient illuminance which is an illuminance around a subject vehicle, and a control unit configured to be capable of executing headlamp control for automatically switching a state of a headlamp of the subject vehicle between an ON state where the headlamp is turned on and an OFF state where the headlamp is turned off.

The control unit switches, in a case where the ambient illuminance is equal to or lower than a predetermined on and off illuminance, the headlamp state from the OFF state to the ON state. Furthermore, the control unit estimates, in a case where the ambient illuminance is higher than the predetermined on and off illuminance, a time required for the subject vehicle to travel to an entrance of a tunnel in front of the subject vehicle, as a required time, switches, in a case where the required time is longer than a predetermined determination time, the headlamp state from the ON state to the OFF state, and keeps, in a case where the required time is equal to or shorter than the predetermined determination time, the headlamp state as the ON state.

For example, in a case where the vehicle travels on a road where two tunnels are built close to each other during the daytime, the lamp state (that is the headlamp state) is automatically switched between the ON state and the OFF state depending on the brightness around the vehicle. Since it is brighter outside the tunnel than inside the tunnel, the lamp state is set to be the ON state inside the first tunnel, is switched from the ON state to the OFF state when the vehicle leaves the first tunnel, and then is switched from the OFF state to the ON state when the vehicle enters the second tunnel. In other words, the lamp state is switched twice. If a distance is short between the two tunnels and a relatively short time is required for the vehicle to leave the first tunnel and enter the second tunnel, the lamp state is switched twice in a short period of time. In such a case, a driver of the vehicle may be inconvenienced.

With the headlamp control device of the present disclosure, when the subject vehicle leaves the first tunnel and it is bright around the subject vehicle (when the ambient illuminance is higher than the predetermined switching illuminance), and in a case where the time required for the subject vehicle to travel to the entrance of the second tunnel is short (in a case where the required time is equal to or shorter than the predetermined determination time), the lamp state is kept as the ON state. Therefore, even if the subject vehicle enters the second tunnel and it is dark around the subject vehicle (even if the ambient illuminance is equal or lower than the predetermined switching illuminance), the lamp state is kept in the ON state. Accordingly, the lamp state is not switched twice in a short period of time. Consequently, it is possible to prevent the driver of the vehicle from being inconvenienced.

According to a fourth aspect of the present disclosure, a headlamp control device includes an illuminance detection device that detects an illuminance around a subject vehicle as an ambient illuminance, and a control unit configured to be capable of executing headlamp control for automatically switching a state of a headlamp of the subject vehicle between an ON state where the headlamp is turned on and an OFF state where the headlamp is turned off, and automatically switching the state of the headlamp between a high-beam state where a headlight angle of the headlamp is set to a high-beam angle and a low-beam state where the headlight angle is set to a low-beam angle.

The control unit switches, in a case where the ambient illuminance is equal to or lower than a predetermined on and off illuminance, the headlamp state from the OFF state to the ON state. Furthermore, the control unit estimates, in a case where the ambient illuminance is higher than the predetermined on and off illuminance, a time required for the subject vehicle to travel to an entrance of a tunnel in front of the subject vehicle, as a required time, switches, in a case where the required time is longer than a predetermined determination time, the headlamp state from the ON state to the OFF state, and keeps, in a case where the required time is equal to or shorter than the predetermined determination time, the headlamp state as the ON state.

Further, the control unit estimates, in a case where the ambient illuminance is equal to or lower than a predetermined switching illuminance when the headlamp state is the ON state, a time required for the subject vehicle to travel to an entrance of a tunnel in front of the subject vehicle, as a first time, switches, in a case where the first time is longer than a first determination time, the headlamp state from the low-beam state to the high-beam state, and keeps, in a case where the first time is equal to or shorter than the first determination time, the headlamp state as the low-beam state.

Consequently, the headlamp control device according to the fourth aspect of the present disclosure has the same advantageous effect as the effect obtained from the headlamp control device according to the third aspect of the present disclosure. It also has the same advantageous effect as the effect obtained from the headlamp control device according to the first aspect of the present disclosure.

In the headlamp control device according to the fourth aspect of the present disclosure, the control unit may be configured to, in a case where the ambient illuminance is higher than the predetermined switching illuminance when the headlamp state is the ON state, estimate a time required for the subject vehicle to travel to the entrance of the tunnel in front of the subject vehicle, as a second time. The control unit may switch, in a case where the second time is longer than a second determination time, the headlamp state from the high-beam state to the low-beam state, and keep, in a case where the second time is equal to or shorter than the second determination time, the headlamp state as the high-beam state.

Consequently, when the subject vehicle leaves the first tunnel and it is bright around the subject vehicle (when the ambient illuminance is higher than the predetermined switching illuminance), and in a case where the time required for the subject vehicle to travel to the entrance of the second tunnel is short (in a case where the second time is equal to or shorter than the second determination time), the lamp state is kept as the high-beam state. Therefore, even if the subject vehicle enters the second tunnel and it is dark around the subject vehicle (even if the ambient illuminance is equal or lower than the predetermined switching illuminance), the lamp state is kept in the high-beam state. Accordingly, the lamp state is not switched twice in a short period of time. Consequently, it is possible to prevent the driver of the vehicle from being inconvenienced.

Configurations of the present disclosure are not limited to embodiments of the present disclosure, which will be described later referring to the drawings. Other objects, features, and advantages of the present disclosure will be readily understood from the description on the embodiments of the present disclosure.

