| 摘要 |
PROBLEM TO BE SOLVED: To obtain a smoke detector reliably detecting a fire with a simple configuration while providing a smoke detection space outside a casing.SOLUTION: The smoke detector, which determines the fire by emitting light into the smoke detection space outside the casing and receiving the light obtained by scattering the emitted light by a scattering body, includes: a light emitting element 7; a first light receiving element 9; a second light receiving element 11; and a polarizing filter 13 which polarizes the light emitted from the light emitting element 7 and the light received by the first light receiving element 9. A fire determination part 15 for determining the fire inputs a light receiving signal of the first light receiving element 9 entered through the polarizing filter 13 and a light receiving signal of the second light receiving element 11 entered without the polarizing filter 13 and determines the fire based on an output ratio of the light receiving signal of the first light receiving element 9 and the light receiving signal of the second light receiving element 11. |
