| 摘要 |
PURPOSE:To obtain the sensing operation high in reliability, by locating the scattering light production area effective to the photo detection at the photo detection element through the opposition to the inlet of smoke. CONSTITUTION:When smoke enters the air gap between the main body case 11 and the cover 19 from the direction A as shown in Figure, it is once introduced in the case 11 from the smoke inlet 11a through the smoke duct as shown in solid lines, and it is discharged through the path opposite to the incoming path via the section 19a. In this case, in the case 11, the main flow and disturbed flow of smoke are biased toward the photo detection element side 16, but since the scattering light generation area 18 is positioned opposingly to the opening of the smoke inlet 11a, the smoke flow all reaches the area 18. Thus, scattering light caused in the area 18 is effectively received at the photo detection element 16 to perform stable smoke sensing. Further, smoke flows inversely from the direction B, and except that the main flow and disturbed flow are biased to the light emitting element 15, the same condition as before is shown to enable stable smoke sensing. |
