Patent ID: 7697140

Claim:
A photoelectric smoke detector for detecting presence of smoke by utilizing a light emitting element and a light receiving element whose optical axes intersect with each other, the photoelectric smoke detector comprising: an air chamber for temporarily reserving air flowing in from outside the smoke detector; a specialized labyrinth function fulfilling part for playing only a labyrinth function of bringing an air flow from the air chamber into an interior space thereof and preventing entry of disturbance light into the interior space; and a smoke detecting part provided above the specialized labyrinth function fulfilling part so that an interior space of the smoke detecting part is communicated with the interior space of the specialized labyrinth function fulfilling part, the smoke detecting part having the light emitting element and the light receiving element built therein and having a small hole for extracting air flow that has passed through a detection area near an intersection between the optical axes of the light emitting element and the light receiving element.