| 摘要 |
PURPOSE:To make it possible to stable detect the presence of heat mass with good accuracy, by providing an optical filter for removing the light spectrum of the flame generated in heat mass and receiving the radiant light transmitted through the optical fiber by a light detection means. CONSTITUTION:The light emitted from heat mass 10 is condensed to the objective lens 14 fixed in a detection head 12 and this condensed light is guided to an optical fiber 16 and only light of a specific wavelength region is transmitted through an optical filter 18 to irradiate a photoelectric element 20. The analogue output of the photoelectric element 20 is amplified by an amplifier 22 and compared with a predetermined threshold value by a comparing circuit 24 to be converted to ON-OFF output and the presence of the heat mass 10 is detected. As the photoelectric element 20, a silicon photoelectric element of which the spectral sensitivity characteristic has a wavelength width of 400-1,100nm as shown by a solid line 38 is selected and, as the optical filter 18, a band-pass filter having a transmission characteristic such that the wavelength of transmitted light is 600-760nm is used. By this method, the effect of flame spectra 34, 36 can be removed. |
