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1. 发明授权

US4125749A Key telephone systems 失效
标题翻译：主要电话系统
公开(公告)号：US4125749A
公开(公告)日：1978-11-14
申请号：US711975
申请日：1976-08-05
申请人： Toshiharu Kinoshita , Yoshio Shinoda , Takashi Oyamada , Mitsuo Masuda , Noritomo Arai
发明人： Toshiharu Kinoshita , Yoshio Shinoda , Takashi Oyamada , Mitsuo Masuda , Noritomo Arai
IPC分类号： H04M9/00 , H04M1/00
CPC分类号： H04M9/007
摘要： The key button telephone system comprises a key service unit and a plurality of key telephone units. The key service unit and each key telephone unit are interconnected by a pair of cables, one of which is used as a talking circuit and the other is used to transmit and receive information signals and operating power. The key service unit comprises a line circuit for supervising the state of a line, a station unit for supervising the line circuit, and for supplying to the key telephone unit an information signal representing the state of the line and the operating power, a switching network controlled by the control output from the station unit for connecting the key telephone unit to the line, and a common control circuit for controlling the line circuit and the station unit. Each key telephone unit comprises a telephone circuit connected to the switching network, a telephone control circuit for supervising the state of the key telephone unit connected to the station unit, and a DC converter for converting a DC voltage supplied from the station unit into a predetermined DC voltage.
摘要翻译：键按钮电话系统包括密钥服务单元和多个密钥电话单元。密钥服务单元和每个密钥电话单元通过一对电缆互连，其中一个电缆用作通话电路，另一个用于发送和接收信息信号和操作电源。密钥服务单元包括用于监视线路状态的线路电路，用于监视线路电路的站单元，以及向密钥电话单元提供表示线路状态和操作功率的信息信号，切换网络由站单元的控制输出控制，用于将密钥电话单元连接到线路，以及用于控制线路电路和站单元的公共控制电路。每个密钥电话单元包括连接到交换网络的电话电路，用于监控连接到站单元的密钥电话单元的状态的电话控制电路，以及用于将从站单元提供的直流电压转换为预定的直流电压。

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