Speaker protection device and speaker protection method

摘要

PROBLEM TO BE SOLVED: To provide a speaker protection device which can prevent destruction of a speaker.SOLUTION: A voltage detection circuit 101 detects a voltage on one end of a voice coil of a speaker. A current detection circuit 104 detects a current flowing in the voice coil. A band-pass filter 102 extracts a voltage value of a prescribed frequency band including a frequency in a rated impedance of the speaker. A band-pass filter 106 extracts a voltage value of a prescribed frequency band including a frequency in the rated impedance. A determination section 1083 calculates the rated impedance using the voltage value and the current value extracted by the band-pass filters 102, 106, and estimates a temperature of the voice coil on the basis of a change rate of the rated impedance, to determine whether the temperature of the voice coil exceeds the preliminarily set upper limit temperature. When it is determined that the temperature of the voice coil exceeds the upper limit temperature, a protection control section 1085 controls to operate a protection circuit of the speaker.SELECTED DRAWING: Figure 1