| 摘要 |
PURPOSE:To control a private broadcasting unit without using an exclusive-use control signal line by detecting an activating instruction from the connected extension telephone set, energizing the private broadcasting unit, and detecting the on-hooking from the extension telephone set and de-energizing the private broadcasting unit. CONSTITUTION:Since a private broadcasting unit 106 is activated through an extension telephone set 110a, a handset is picked up and a private broadcasting unit activating button is pushed down and inputted. A central control part 102 confirms that the private broadcasting unit 106 is not used, and sends the instruction of the bus setting to the private broadcasting unit 106 toward a time switch 103. The private broadcasting unit 106, when a voice pattern from an incoming highway 220 is sent, energizes a speaker driving circuit 304 and outputs acoustically the sent voice pattern. When a desired broadcasting from the extension telephone set is completed, the handset of the extension telephone set is placed. The central control part 102 sends a bus releasing instruction to the time switch 103. |
