| 摘要 |
PROBLEM TO BE SOLVED: To very easily detect objective gas stably for a long period without adjusting a zero point or the like frequently. SOLUTION: An electric signal about an acoustic wave when no detection gas exists in a space is synchronized (locked) within a feedback circuit 20 constituting a phase locked loop. Then, the electric signal about the acoustic wave when the detection gas exists in the space is introduced into the feedback circuit 20, the synchronization (lock) is released in the feedback circuit 20, a phase change of the electric signal resulting from a propagation velocity (sonic velocity) of the acoustic wave is read out as an electric signal to detect the presence of the detection gas. COPYRIGHT: (C)2005,JPO&NCIPI
|
