| 摘要 |
PURPOSE:To operate a control circuit inserted to telephone line to prevent the incoming ringing of the telephone set and covering the control circuit when the operater returns to one's desk by providing the control switch which is operated when the operator leaves or returns one's desk to cope with a telephone set and actuating the switch when each operator leaves one's desk. CONSTITUTION:The switches S1-Sn are provided to the telephone set respectively within a group, and storage circuits F1-Fn are set to correspond to the switches S1-Sn in order to store the state of operation for these switches. The outputs of the circuits F1-Fn are supplied to an NOR circuit, and the output of the NOR circuit is supplied to control circuits C1-Cn provided within connection terminals T1-Tn and L1-Ln of the telephone circuit. When all members of the group operate the switches S1-Sn when they leave their desks, the circuits C1-Cn are actuated by the output of the NOR circuit to set the telephone circuit at a high impedance and thus to prevent the ringing of the telephone. In case even one of the members comes back to his or her desk and operates the switches S1-Sn, the operations of the circuits C1-Cn are recovered to obtain the normal incoming state. |
