PURPOSE: To simplify wiring and to reduce the cost of an interphone device, by using a power line to perform an interphone work and making the information of occurrence of extraordinary events possible through the power line.
CONSTITUTION: Power supply cords 6 and 10 supply an electric power to a master set 1 and secondary set 2 and, at the same time, serve as transmission lines of modulated sound signals when they are used as an interphone. An antenna 17 is installed to the master set 1 and the master set 1 receives a radio signal from an intrusion transmitter and fire transmitter functioning as a warning signal generating means through the antenna 17 and inputs the radio signal into a processing device 30 after demodulating and amplifying said signal at a receiving circuit 23. When the processing device 30 recognizes that an extraordinary situation occurs and a warning sound must be generated, generates a warning sound signal through a signal changeover circuit 38. This signal is amplified by a low frequency amplifier circuit 15 and given to a loudspeaker/microphone from a transmission reception changeover switch 25, and thus, the warning sound is generated.
| JPS62115550 | ALARM CONTROLLER |
| WO/2022/067118 | TAMPER-RESISTANT WEARABLE CARETAKING DEVICE |
MINAMI KATSUJI
OKAMOTO AKIRA
YASUOKA NORIO
HATAKEYAMA YASUYUKI
MATSUZAKI YUKINORI
| JPS4990097A | 1974-08-28 | |||
| JPS56104566A | 1981-08-20 |
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