| 摘要 |
PROBLEM TO BE SOLVED: To provide an alarm which prevents a detection of battery voltage drop in response to sounding while a battery voltage is at a voltage equal to or more than a circuit operation voltage. SOLUTION: When a sensor detects an abnormality, a sounding circuit is made to sound. A voltage detection IC detects battery voltage drop, when a battery voltage is supplied to the input and the supplied battery voltage falls below a drop detection voltage, and then cancels the detection of the battery voltage drop, when the battery voltage exceeds a detection cancellation voltage that is higher than the drop detection voltage. A microcomputer supplies a battery voltage, which is boosted by a booster circuit after sounding by the sounding circuit ends, to the input of the voltage detection IC to cancel the detection of battery voltage drop. COPYRIGHT: (C)2009,JPO&INPIT |
