| 摘要 |
PURPOSE:To prevent the useless consumption of power by releasing a control line during a time when a key telephone set is in an idle state, and turning off a power supply line from a main equipment to the push-button telephone set. CONSTITUTION:On the key telephone set 21 side, a hook switch 12 is connected in series to the control line 10, and the open/close contact points 15 of a latching type relay 11 connected in parallel with a communication line via an excitating circuit 14 are connected to said hook switch 12 in parallel. On a main equipment 1 side, a relay control means 18 to impress a switching pulse from a latcing type relay 11 to a targeted one of the respective communication lines, is provided. In an idle state, both the points 15 and the hook switch 12 are turned OFF to release the control line 10, and no idle current is conducted. In case of initiating from the key telephone set 21 side, with a handset is hooked OFF, the switch 12 turns ON, and the control line 10 is connected. In case of initiating from the main equipment 1 side, the relay control means 18 switches the latching type relay 11 on the telephone set side to connect the points 15 and further to connect the control line 10. |
