| 摘要 |
PURPOSE:To detect the concn. of smoke with high accuracy even when light emitting quantity and light receiving quantity change by the change in the characteristics of a light emitting means and a light receiving means, by detecting the concn. of smoke from the variation rate of an output signal. CONSTITUTION:This smoke detector is equipped with a light emitting means M2 emitting light in an exhaust passage, a light receiving means M3 receiving said light emitted, a modulation means M4 modulating the physical quantity of said light in a predetermined modulation degree and a smoke concn. calculation means M5 calculating the concn. of smoke on the basis of the variation rate of the output signal from the means M3. Then, by modulating the physical quantity relating to the generation of smoke, the concn. of the smoke in exhaust gas after combustion is varied. The variation rate from the output signal of the means M3 detecting the projection light to the exhaust gas from the means M2 is calculated to calculate the concn. of the smoke. By this method, even when light emitting quantity and light receiving quantity change by the change in the characteristics of the means M2, M3 and the contamination of light emitting and receiving surfaces, the concn. of the smoke can be detected with high accuracy. |
