Circuit for controlling an audio signal output of a television

Abstract

A circuit for controlling the audio signal output of a television, in which it is determined whether video and audio signals are input from an external source, such as a video tape recorder. If so, then the audio output signals are properly controlled according to whether the audio signal are mono or stereo-type signals. The circuit includes an audio input state detecting circuit for determining the audio input state by employing an exclusive OR gate and at least two analog/digital converters, and a video signal detecting circuit for detecting whether or not video signals are input. A switching circuit performs switching operations through an AND gate which logically combines the output of the audio signal state detecting circuit and the output of the video state detecting circuit. Therefore, even in the case where the audio signal is a mono-type signal, a quasi-stereo sound is output through both left and right speakers.

Dependencies are inferred from the claim text.