| 摘要 |
PROBLEM TO BE SOLVED: To obtain an alarm maintaining the ease of hearing of the entire alarm sound while suppressing current consumption when alarm sound rings during voltage drop of a battery. SOLUTION: The alarm includes: a battery 1; a voltage detection IC 3 for detecting supply voltage of the battery 1; a fire detection circuit 5 as a state detection circuit for detecting a state change based on a physical phenomenon; a control part 2 for receiving a state detection signal of the fire detection circuit 5; and a sound ringing circuit 4 controlled by the control part 2 to output alarm sound. The control part 2 determines whether the alarm sound has to be rung on the basis of the state detection signal from the fire detection circuit 5, and makes the sound ringing circuit 4 ring alarm sound when the ringing of the alarm sound is determined to be necessary, and the sound ringing circuit 4, when a drop of supply voltage of the battery 1 is detected while the alarm sound rings, rings the alarm sound with sound pressure lower than during normal ringing, about alarm sound in which peak current exceeds a predetermined value, and rings alarm sound with sound pressure equal to that during normal ringing about alarm sound in which the peak current is not higher than the predetermined value. COPYRIGHT: (C)2011,JPO&INPIT
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