| 摘要 |
PURPOSE:To reduce the influence of external noise by integrating a photodetector and a smoke sensing circuit into one integrated circuit. CONSTITUTION:Light projected from a projecting element 3 is dispersed by smoke and the direction of the light is changed by a prism part 8a of a photodetection lens 8. Afterwards, the light is condensed onto a integrated circuit 7 by the lens part 8a. In the integrated circuit 7, in addition to the photodetector which is a photodiode, a smoke detecting circuit to detect the existence of the smoke based on the output of the photodetector, projecting element driving circuit and power supply circuit are integrated. In a circuit board 5, the other circuit parts are loaded in addition to the integrated circuit 7 and the projecting element 3. An optical pedestal 2 holds the projecting element 3 and the photodetection lens 8 and is coupled to the circuit board 5. |
