To provide a gas safety device which does not use an exclusive pressure sensor and realizes pressure measurement at a low price.
The propagation gain in a gas between ultrasonic transmitter-receiver 2A, 2B is proportional to the density of the gas, and the density is proportional to the pressure. Therefore, the higher the pressure, the higher the level of a reception signal. By performing peak detection on the reception signal by a window comparator or the like and adjusting the amplification degree of a variable gain amplifier circuit 4 so that a peak level becomes constant, the amplification degree indicating signal of the variable gain amplifier circuit 4 follows the gas pressure. On the basis of the value, the pressure value is determined.
COPYRIGHT: (C)2006,JPO&NCIPI
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Daisuke Nagano
Kentaro Fujii