| 摘要 |
<p>PURPOSE:To accurately discriminate entrance to a tunnel and other cases so as to light a vehicular headlamp and the like without malfunction. CONSTITUTION:A solar radiation sensor 1 for detecting front upward illuminance of a vehicle and the like is provided and approach to a tunnel is judged by a process circuit 3 only when detected illuminance is 500 Lx or higher and also illuminance changing rate is a specified value or less. When the detected illuminance is less than 50 Lx a headlamp 5 is lighted. In the case of approach to undernearth a bridge girder and the like, the illuminance changing rate exceeds the specified value and abruptly changes and therefore the approach is clearly discriminated from that to a tunnel so that malfunction cannot occur.</p> |
