| 摘要 |
<p>PURPOSE:To improve eye-confirmation of a vehicle traveling in daytime, in a head light unit comprising a travel beam and a pass-by beam, by lightening the travel beam when an optical sensor for detecting the outdoor brightness had detected a brightness higher than specific level. CONSTITUTION:When it is dark around a motorcycle under night time travel, the resistance of an optical sensor 8 is high to reduce the current flowing through said sensor 8. Consequently, the voltage at the point (a) is approximately same with the source voltage and higher than a referential voltage at the point (b) preset in a comparator 9 thereby no output is produced from the comparator 9. In this case, B contact 13b of a relay 12 is closed to enable selective lighting of a travel beam 2 or a pass-by beam 3 in the head light through operation of a changeover switch 5. While since the resistance of the optical sensor 8 will decrease under daytime travel, an output is produced from the comparator 9 to close A contact 13c of the relay 12 thus to light the travel beam 2 automatically.</p> |
