Audio circuit
An audio circuit drives a speaker. A DSP corrects an audio signal S 1 according to the state of the speaker. An amplifier drives the speaker according to a corrected audio signal S 3.
1. An audio circuit structured to drive a speaker, comprising:
a signal processing unit structured to correct an audio signal according to a state of the speaker;
an amplifier structured to drive the speaker according the corrected audio signal; and
at least one sensor each structured to detect state of the speaker,
wherein the at least one sensor includes a temperature sensor structured to detect a temperature of the speaker, and
wherein the signal processing unit superimposes, on the audio signal, a correction signal having a low-frequency component (20 Hz or less) outside the audio band.
2. The audio circuit according to claim 1 , wherein the at least one sensor includes a vibration sensor structured to detect a vibration of the speaker,
and wherein the signal processing unit superimposes, on the audio signal, a signal having opposite phase to the vibration.
3. The audio circuit according to claim 1 , wherein the at least one sensor includes a magnetic sensor structured to detect a magnetic field generated by the speaker.
4. The audio circuit according to claim 1 , further comprising a detection circuit structured to measure a current that flows through the speaker,
wherein the signal processing unit corrects the audio signal according to the temperature of the speaker.
5. The audio circuit according to claim 1 , wherein a plurality of the speakers and a plurality of the audio circuits are used as a set,
and wherein a correction for each audio circuit is controlled such that output characteristics become uniform between the plurality of speakers.
6. The audio circuit according to claim 1 , wherein a plurality of the speakers and a plurality of the audio circuits are used in multi-channel audio system, and
wherein each of the plurality of the audio circuits superimposes the correction signal on the audio signal when a difference between the temperature of the speaker of a corresponding channel and the temperature of the speaker of another channel exceeds a threshold.
7. A speaker unit comprising:
the speaker; and
the audio circuit according to claim 1 structured to drive the speaker,
wherein the speaker and the audio circuit are monolithically integrated.
8. The speaker unit according to claim 7 , further comprising nonvolatile memory structured to store predetermined audio data,
wherein the signal processing unit is capable of reproducing the audio data.
9. A vehicle comprising the speaker unit according to claim 8 .