| 摘要 |
<p>PROBLEM TO BE SOLVED: To turn on a headlight either automatically or voluntarily in such a manner that a light receiving window opposed to an illuminance sensor is provided with a received light quantity varying means comprising a cap for varying light quantity received from the outside illuminance. SOLUTION: The casing 3 of a headlight 1 for a bicycle has a bulb 2 mounted therewithin, and, under surface of the casing 3, a light receiving window 4 is arranged opposed to an illumination sensor 5 mounted in the casing 3. On the periphery of the light receiving window 4, locking projections 6 are formed, and a non-translucent cap 7 is removably mounted. When the light receiving window 4 is not covered with the cap 7, the brightness of the outside field is directly detected by the illumination sensor 5, so that the headlight 1 is automatically turned on. While, when an user wants to light under the bad condition of visibility such as fogging the user can shut the light receiving window 4 by the cap 7 so as to turn on the headlight. However, using an semi-translucent cap 7, lighting according to the brightness of the outside field will be also capable.</p> |
