| 摘要 |
PROBLEM TO BE SOLVED: To improve measurement accuracy by quickening a purification speed in a chamber during calibration operation and shortening a recovery time after calibration operation. SOLUTION: A gas detector is provided with the chamber 40 having an opening 43 for introducing external air and a gas sensor 20 for detecting gas concentration in the outside of the chamber 40 from the external air flowing into the chamber 40. It is provided with a heat catalyst 50 for purifying internal air in the chamber 40 to calibrate a reference value of the gas sensor 20 and a catalyst heater 60 for activating the heat catalyst 50. In the calibration of the reference value of the gas sensor 20, conductance of the opening 43 is changed while opening the opening 43. To explain concretely, conductance of the opening 43 is reduced when the catalyst heater 60 is driven to activate the heat catalyst 50, and conductance of the opening 43 is increased when the catalyst heater 60 stops. COPYRIGHT: (C)2003,JPO
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