| 摘要 |
PROBLEM TO BE SOLVED: To provide a speaker protection circuit and a speaker protection method for surely preventing a physical destruction due to a speaker driven with a signal exceeding its rating for a comparatively long time and carrying out transition to a sound volume limit state and return to an ordinary state from the limit state without giving a sense of discomfort to an operator. SOLUTION: Variable gain amplifiers 12, 13 and an output amplifier 14 amplify an audio input signal to drive the speaker 15. A power detection circuit 21 detects an output power of the output amplifier 14, and when the output power exceeds the rating output power of the speaker 15, the detection circuit 21 outputs a rating over detection signal to a timer circuit 22, and the timer circuit 22 outputs a sound volume limit signal to the amplifier 12 when the rating over state continues for a prescribed time so as to prevent the speaker 15 from being continuously driven by the power in excess of the rating power of the speaker 15. COPYRIGHT: (C)2006,JPO&NCIPI |
