Patent ID: 6201537
Filing Date: 2001-03-13
Classification: H03G

Abstract:
In a display device comprising:a monitor having on-screen display of mute, microphone, condenser microphone, and volume control, said monitor having sound function keys for selection of a microphone, a speaker, a condenser microphone, and volume control to activate said on-screen display;a housing comprising a microcomputer generating pulsewidth duty cycles when a sound function key is selected;a sound amplifier control circuit for controlling sound output through a speaker based on said pulse width duty cycles generated by said microcomputer; anda sound output unit for generating sound after changing input sound based on the output signal generated by the sound amplifier control circuit;the improvement comprising:a multiplexer for switching the microphone according to the control signal generated by the microcomputer, said multiplexer having means for decreasing said sound output when said sound output exceeds a predetermined level whereby howling is prevented.