| 摘要 |
PURPOSE:To enable fire detection by a relative simple device by detecting a waveform component peculiar to the fire detection in radiation that a flame emits, and generating a warning when its detection output varies continuously and irregularly and its variation quantity is larger than a specific value. CONSTITUTION:A BPF 11 extracts the wavelength component of almost 4.4mum in the radiation emitted by the flame and an electric BPF extracts a frequency of 1-10 of HZ through a pyroelectric sensor 21 and an amplifier 22. Its signal is inputted to a flicker width measuring circuit 321 through an D/D C51 to detect the difference between maximum and minimum values in each cycle. Its flicker width measurement signal S321 is inputted to a level check circuit 322, which outputs an H-level decision signal S322 when the flicker width is within a specific range. A continuity check circuit 310, on the other hand, checks that the output signal of the circuit 51 continues and outputs an L-level signal S310 and the circuit 323 calculates the histogram of the signal S321 and outputs an irregularity decision signal S323. A fire decision circuit 330 outputs a warning from a fire output circuit 41 on receiving the signals S322, S310, S323, and a frequency signal from the circuit 324.
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