| 摘要 |
PROBLEM TO BE SOLVED: To realize an excellent smoke inflow performance by suppressing an internal reflection by light from a light emission part without providing a labyrinth structure.SOLUTION: A scattered light type smoke detection structure is provided by placing a light emission element 26 and a light reception element 30 on a smoke detection part 18. A polarizing beam is irradiated on a smoke detection space 20 by placing a polarizing filter 28 in the front of the light emission element 26, and the light reception element 30 receives scattered light due to the smoke of the polarizing beam. The irradiation region of the smoke detection part 18 irradiated with the polarizing beam from a light emission part 22 provided with the light emission element 26 and the polarizing filter 28 is set as a bottom surface 32 becoming an irradiation plane, and the polarizing filter 28 is set such that the polarizing direction of the polarizing beam that irradiates the bottom surface 32 becomes parallel to an incident plane. In addition, an incident angle α to the bottom surface 32 of the polarizing beam is set to a predetermined angle low in reflectance, preferably, a predetermined Brewster angle which is zero in reflectance.SELECTED DRAWING: Figure 1 |
