| 摘要 |
PURPOSE:To improve reliability by lowering the '0' point level of a detecting output for diffused light caused by smoke. CONSTITUTION:On upper walls, plural labyrinth members 9 are formed so as to stand up, a smoke detection room is formed in an area surrounded by these labyrinth members 9, and a light emitting element 12 and a light receiving element 13 are arranged at the center of the smoke detection room so as to cross respective optical axes. A labyrinth member 91 faced to the light emitting plane of the light emitting element 12 is formed comparatively longer than another labyrinth member 9 so that the view of the light receiving element 13 to the smoke detection room can be only the front face, and a gap 20 is formed by a light shielding board 14 for shielding light to directly reach from the head and the light emitting element 12 to the light receiving plane of the light receiving element 13. |
