| 摘要 |
PURPOSE:To enable durable and automatic detection of gas atmosphere, by installing a plurality of atmosphere sensor elements, switching means allowing these elements to act after consecutive switching and judging means for atmosphere responding to the sensor. CONSTITUTION:Semi-fixed resistances VR1-VR4 are connected in series to sensible bodies S1-S4 respectively and the individual resistance, in response to resistance value of the sensible bodies S1-S4 in a concentration at the start of alarm is adjusted in such a way that each output voltage V1-V4 becomes equal. Upon operating interlinked change-over switches SW1, SW2, by heaters H1-H4 at the initial stage of receiving a current, the sensible bodies S1-S4 are heated and an output voltage VS is issued. This VS is delivered to a discriminating circuit for the gas atmosphere. By setting life of the gas detection element in such a way that, the count of generations of output signal VO at its predetermined value causes automatic switching to the following detecting element, the element, upon its reaching the expiration of its life, can automatically cause the succeeding detecting element to operate. |
