| 摘要 |
A light scattering type smoke sensor has a plurality of labyrinth members 9 for facilitating an inflow of smoke entering from outside. A light emitting device 12 radiates light toward a smoke detecting chamber formed in a centre portion by the labyrinth members, and a light receiving device 13 detects light which is scattered by the smoke in the smoke detecting chamber. A labyrinth member 91 is at 45{ to the optical axis of the light emitting means (fig 9) and has a reflecting face 91b for reflecting light radiated from the light emitting device in a direction opposite to the light receiving device. In other embodiments, the axes of the emitting device and detecting device intersect at a scattering angle in the range 60 to 80{, and a projecting area of the emitting means (fig 9) is within a height of the member 91. |
