| 摘要 |
PROBLEM TO BE SOLVED: To provide an alarm sound drive circuit capable of preventing variation in sound pressure output by a sound emitting unit due to unevenness in power consumption thereof.SOLUTION: The alarm sound drive circuit includes: a voltage detection section 5 that detects power supply voltage; a temperature detection section 6 that detects ambient temperature of a siren SI1; and a current detection section 7 that detects current consumption by the siren SI1. A control section 4 stores a threshold value of the current consumption associated with the power supply voltage and the ambient temperature, and the plural pattern tables distributed based on the threshold value. The control section 4 compares a value of the detected current consumption and the threshold value to select any one of the pattern tables, and adjusts the drive power to maintain the sound pressure output by the siren SI1 at a constant level while referring to the selected pattern table. |
