| 摘要 |
PURPOSE:To prevent misoperation owing to influence by miscellaneous gas, by delaying the start time for heat cleaning, when the miscellaneous gas which is not an object to be detected exists and extending the finishing time for heat cleaning, when the miscellaneous gas exists during heat cleaning. CONSTITUTION:When the first gas detecting element 5 is exposed in the atmosphere of miscellaneous gas before the start of heat cleaning of the first heater 18, the applying time of heater voltage is delayed until the miscellaneous gas goes away, and the finishing time of applying heater voltage is extended until the miscellaneous gas goes away and breaks away, when the first gas detecting element 5 is exposed in the atmosphere of miscellaneous gas during the start of heat cleaning of the first heater 18. Therefore, it is avoided that the first gas detecting element 5 is exposed in the atmosphere of miscellaneous gas during heat cleaning and in case that the concentration of miscellaneous gas is raised during the heat cleaning, the breakaway of the miscellaneous gas is accelerated by extending the finishing time of the cleaning. |
