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    • 6. 发明专利
    • CALLING DEVICE
    • JPS586655A
    • 1983-01-14
    • JP10524481
    • 1981-07-06
    • NIPPON SIGNAL CO LTD
    • MUROI SHIGEHARUHARADA JIYUNICHIROUOCHIAI TOSHIO
    • H04M9/00
    • PURPOSE:To reduce the number of cables laid between a master calling device and subordinate calling devices, by connecting the subordinate calling devices in parallel to a common voice line, and sending out a call and a selection signal to every subordinate calling device through control lines. CONSTITUTION:When a call switch 7a is pressed, a photocoupler 20 turns on to turns on the lamp 21 of a selection display circuit 6a. When any of call switches 7b-7n is pressed, a corresponding lamp turns on. Therefore, a person in change conforms which subordinate calling device should be put in a calling state next on the basis of the lamp indication. When a selection switch 5a is closed, a photocoupler 30 turns on, so a current flows through the relay 31 in a connection control circuit 8a to close a contact 4a, so that a subordinate calling device 2a is connected to a voice bus line 3 and then held in the calling state. When any of selection switches 5b-5n is closed, a corresponding subordinate caling device is held in the calling state similarly.