| 摘要 |
PURPOSE:To switch function of transmission and reception without depressing a changeover switch by providing a human body detecting circuit and a sound volume detecting circuit on the front of a transmission and reception use loudspeaker. CONSTITUTION:When a detecting signal is inputted from a human body detecting circuit 6, and also a detecting signal is inputted from a sound volume detecting circuit 7, the connection of a transmission and reception switching circuit 2 is switched to a transmitting circuit 3 side immediately. Once the connection is switched to the transmitting circuit 3 side, the switching circuit 2 is connected to the transmitting circuit 3 side until the detecting signal from the human body detecting circuit 6 stops, or until the detecting signal from the sound volume detecting circuit 7 comes not to be inputted exceeding a prescribed time. Accordingly, it becomes unnecessary that a speaker switches the transmitting and receiving functions by using a switch, etc. |
