PROBLEM TO BE SOLVED: To provide a fire sensor wherein it is not necessary to make a plurality of kinds of ultrasonic waves be sent from a sound source part in spite of allowing estimation of the kind of a particle floating in a monitoring space.

SOLUTION: The sound source part 1 sends a single-pulse-like ultrasonic wave. A signal processing part 4 deciding presence of a fire based on output of a wave reception element 3 has: a storage means 44 storing related data between a frequency of each frequency component based on a density and the kind of the floating particle and an attenuation amount of an intensity from a reference value; a frequency component extraction means 40 extracting the intensity of each frequency component from the ultrasonic wave detected by the wave reception element 3; a particle kind estimation means 41 estimating the kind of the floating particle by use of the related data and the extracted intensity of each frequency component; a smoke density estimation means 42 estimating a smoke density of the monitoring space based on the attenuation amount of the intensity of the specific frequency component from the reference value when the estimated particle is a smoke particle; and a fire decision means 43 deciding the presence of the fire from the estimated smoke density.

COPYRIGHT: (C)2009,JPO&INPIT

【課題】監視空間に浮遊している粒子の種別を推定可能としながらも、音源部から複数種の超音波を送波させる必要のない火災感知器を提供する。
【解決手段】音源部１は単パルス状の超音波を送波する。受波素子３の出力に基づいて火災の有無を判断する信号処理部４は、浮遊粒子の種別および濃度に応じた各周波数成分の周波数と強度の基準値からの減衰量との関係データを記憶した記憶手段４４と、受波素子３で検出された超音波から各周波数成分の強度を抽出する周波数成分抽出手段４０と、抽出された各周波数成分の強度と関係データとを用いて浮遊粒子の種別を推定する粒子種別推定手段４１と、推定された粒子が煙粒子のときに特定の周波数成分の強度の基準値からの減衰量に基づいて監視空間の煙濃度を推定する煙濃度推定手段４２と、推定された煙濃度から火災の有無を判断する火災判断手段４３とを有する。
【選択図】図１