| 摘要 |
PURPOSE:To simultaneously detect and display the disconnection of a heater wire and a semiconductor, by heating the heater wire of a gas detection element equipped with the metal oxide semiconductor and the heater wire by a pulse power source. CONSTITUTION:The heater wire 1a of a gas detection element 1 is heated by the output of a pulse generator PG and, when the heater wire 1a is disconnected, the voltage drop of a resistor R2 disappears and a transistor TRQ2 is turned OFF. By this mechanism, output is generated in a comparator COM2 and TRQ3 is turned ON to light a trouble display lamp LED2. When the semiconductor 1c of the detection element 1 is disconnected, voltage drop due to a resistor R4 decreases sharply to generate output in the comparator COM2. The continuity of TRQ3 is achieved by this output to light LED2. By this method, the disconnection of the heater wire and the semiconductor can be simultaneously detected and displayed. |
