| 摘要 |
<P>PROBLEM TO BE SOLVED: To detect smoke density more precisely by estimating density of each of a plurality of kinds of suspended particle even when the particles are mixed. <P>SOLUTION: An ultrasonic wave of a plurality of frequency components sent by a sound source 10 is received and converted into an electric signal by a receiver 20. An attenuation amount detection part 41 finds attenuation amounts of the ultrasonic wave, sent by the sound source 10 and received by the receiver 20, by the plurality of frequency components, respectively. A density estimation part 42 estimates density of each kind of suspended particles present in the space between the sound source 10 and receiver 20 by using the attenuation amounts by the frequency components that the attenuation amount detection part 41 detects and known attenuation coefficients by the suspended particles. An output part 43 sends a fire alarm when the suspended particles found by the density estimation part 42 includes smoke particles and found density of the smoke particles is within a predetermined determination range. <P>COPYRIGHT: (C)2012,JPO&INPIT |
