| 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, transistors TRQ1, Q2 are turned OFF and the output of an NOR circuit comes to H while output is generated in a comparator COM2. TRQ4 is turned ON by this output and a trouble display lamp LED2 is lighted to inform trouble. When the semiconductor 1a of the detection element 1 is disconnected, voltage drop of a resistor R5 almost comes to 0V. by this mechanism, output is generated in the comparator COM2 and TRQ4 is turned ON while LED2 is lighted. By this method, the disconnection of the heater wire and the semiconductor can be simultaneously detected and displayed. |
