| 摘要 |
PURPOSE: To prevent an alarm from being generated by mistake except in case of a fire by judging whether or not the position of the center of gravity found from the detection result of the frequency of a specific space is in a previously set area. CONSTITUTION: A triangle which approximates a histogram having photodetection intensity on the axis of abscissas and detection frequencies on the axis of ordinates is formed by regarding a vertex in the histogram as one vertex C of the triangle, the point where the frequency is zero and the least photodetection intensity is obtained as a vertex A, and the point where the least photodetection is obtained as a vertex B. At this time, the angle ACD or BCD which is smaller is used as a 1st parameterϕ. As for spectral data obtained by processing a detection signal through Fourier transformation, a specific frequency section is divided into small sections and the means value is found from calculated attenuation values between small sections, and this value is regarded as the attenuation value of the specific frequency space and used as a 2nd parameter N. It is judged that a fire take place when the center of gravity found from the detection result of the frequency of aϕ-N space is present in the area of the predetermined parametersϕand N, and an alarm is outputted.
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