Patent ID: 6710820
Filing Date: 2004-03-23
Classification: H04N

Abstract:
An audio muting apparatus comprising:a D/A converter: control means for gradually varying a converted output voltage from said D/A converter from an initial voltage to a prescribed voltage when performing muting, and gradually varying the converted output voltage from the prescribed voltage to the initial voltage when releasing the muting; and muting means for passing an audio signal in such a manner that an impedance between an audio signal path and a ground level is increased when the converted output voltage becomes the initial voltage, and interrupting passage of the audio signal in such a manner that the impedance between the audio signal path and the around level is decreased when the converted output voltage becomes the prescribed value wherein said initial voltage is set in the vicinity of 0 V, said muting means includes a muting transistor with a collector connected to said audio signal path, an emitter connected to ground and a base supplied with said converted output voltage, and said control means slows down the speed of reducing the converted output voltage when the converted output voltage is caused to fall to cross the vicinity of 0.6 V.