| 摘要 |
The alarm drive circuit according to the present invention includes a control unit, a voltage detection unit to measure a power supply voltage, a temperature detection unit to measure an ambient temperature of a sound generator, and a current detection unit to measure consumption current in the sound generator. The control unit stores a threshold of the consumption current associated with the power supply voltage and the ambient temperature, and two or more pattern tables separated by the threshold. The control unit makes comparison of the measured consumption current value with the threshold and selects one of the two or more pattern tables based on a result of the comparison, and adjusts the intended drive power with reference to the selected pattern table to keep the sound pressure of sound outputted from the sound generator constant. |
