| 摘要 |
PURPOSE:To disconnect a slave telephone set from a telephone circuit even when the slave telephone set is in use by providing a slave set control part composed of a circuit switching control means which connects and disconnects the slave telephone set to and from the telephone circuit, and controlling said circuit switching control means when a signal is outputted from an abnormality sensor to a master set control part and disconnecting the slave telephone set from the telephone circuit. CONSTITUTION:When a smoke detector 5 detects smoke, relays 7 and 8 are operated to disconnect the telephone circuit 1 from the master telephone set 3 and connect to a microcomputer side 6, and the slave telephone set control means 6e outputs a disconnection signal A for disconnecting the slave telephone set 2 from the telephone circuit 1. A circuit disconnection control means 6f turns off the relay 8 after the output of the disconnection signal A and operates the relay 8 again a specific time (t) (normally 3-5sec) later to make a relay contact 8a. Thus, dial pulses B are sent out to the telephone circuit 1 and an abnormality alarm tone generating means 6d sends out an abnormality alarm tone C indicating that the smoke detector 5 operates. |
