Patent ID: 8243968

Claim:
An audio equipment, comprising: an audio output amplifier that amplifies an audio signal; and a speaker that outputs a sound based on the amplified audio signal; wherein the audio output amplifier outputs a high signal as an error signal to protect the audio output amplifier when an abnormal operation occurs; the audio equipment further comprises a rectifier circuit to stabilize the error signal that is output by the audio output amplifier; the rectifier circuit includes a diode; a power supplied to the audio output amplifier is shut off based on the output from the rectifier circuit; an abnormal state detection signal is output to a microcomputer based on a condition that the output from the rectifier circuit is more than a predetermined voltage; the microcomputer shuts off the power supplied to the audio output amplifier when the abnormal state detection signal is input continuously for a predetermined time; the error signal rectified by the rectifier circuit is output to an abnormality signal output circuit, the abnormality signal output circuit includes a first transistor with a base coupled with a cathode side of the diode, and a second transistor with a base grounded through the first transistor, an emitter coupled with a signal voltage source of the abnormal state detection signal, and a collector coupled with the microcomputer; when the output from the rectifier circuit becomes more than a predetermined voltage and the first transistor is turned on, the second transistor is also turned on and a high signal as the abnormal state detection signal is output to the microcomputer; and the microcomputer judges that the audio equipment is in an abnormal state and shuts off the power supplied to the audio output amplifier when the high signal is input continuously for a predetermined time.