| 摘要 |
PURPOSE:To decrease the drift with lapse of time even under high-temp. driving conditions by intermittently driving a heating means for heating a gas sensing part to an operating temp. by a heating control means, thereby shortening the net driving time. CONSTITUTION:The heating control means 12 drives the heating means 9 to periodically turn on and off the heating thereof. Namely, an astable multivibrator 14 oscillates continuously at a period T to output the electric signals of the period T. A comparator 16 is inputted with the electric signals of the period T, compares the same with the threshold possessed by the comparator itself and outputs H and L signals. A relay 15 opens and closes relay contacts 13 according to the output signals of the comparator 16. Consequently, the heater part 3 of the gaseous carbon dioxide sensor 1 is intermittently driven to turn on and off the heating at the period T by the heating means 9 and the substantial driving time is shortened to a half. The actual driving time of the gas sensing part 2 is shortened in such a manner and the drift of the output signals with lapse of time by thermal deterioration is suppressed. The life of the detector is thus prolonged. |
