| 摘要 |
<p>The fire alarm (1) has a back-up-battery (8) reducing internal power supply of the fire alarm. A power failure detecting device includes a microprocessor which detects failure of a commercial power supply (6) and causes change over in the internal power supply by the back-up-battery. A carbon monoxide gas sensor (14) includes a metal oxide semiconductor as a gas sensor element (18), and a heating element (16) for heating the metal oxide semiconductor. A microprocessor (2) controls heat current of the heating element as an indicator for interrupting the commercial power supply.</p> |
