| 摘要 |
<p>PURPOSE:To provide a smoke detector with a good rising characteristic eliminating effect by variation in the quantity of light of a light emitting element by detecting the quantity of light from a reflection mirror with two light receiving elements. CONSTITUTION:Light from a light emitting element 11 is partially reflected on a half-mirror 13 and enters a light receiving element 15. The rest of the light is reflected on a reflection mirror 12 transmitting the half mirror 13 and enters a light receiving element 14. Aluminum evaporated films 18 and 19 in front thereof 12, which are charged at a high voltage adsorb particles of smoke to reduce the quantity of the light reflected sharply. The output of the light receiving elements 14 and 15 are connected to a differential amplifier 16. When a difference between the outputs exceeds a set value, an alarm sounds.</p> |
