| 摘要 |
<p>A telephone hand-free apparatus comprises a housing; a telephone receiving case installed in the housing, the telephone receiving case being so sized and constructed as to receive therein a portable telephone; a board on which a control circuit is arranged, the board being installed in the housing; an external microphone operatively connected to the control circuit and exposed to the outside of the housing; an external speaker operatively connected to the control circuit and installed in the housing; a connection cable extending from the control circuit, so that when the connection cable is connected to a socket of the portable telephone, the external microphone and the external speaker become operative in place of a microphone and a speaker of the portable telephone; and an electric power source which energizes the control circuit. The control circuit includes a muting section which makes the external microphone inoperative while the control circuit is receiving a voice signal from the portable telephone through the connection cable.</p> |
