| 摘要 |
PURPOSE: To obtain a photoelectric smoke detector in which the S/N ratio can be enhanced while reducing the cost of the circuitry. CONSTITUTION: The photoelectric smoke detector comprises a light emitting part 23 for irradiating the smoke passage with a light, and a light receiving part 24 for receiving the light emitted from the part 23 and scattered by the smoke, and a slit 25 for shielding the light receiving part from disturbance light, all of them being housed in a case 2. A light emitting element 26 provided at the light emitting part 23 comprises a current construction type LED having a constricted light emitting region and the slit 25 has a knife edge type tip end on the passage side. |
