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2. 发明授权

US4145577A Ringing control apparatus 失效
标题翻译：振铃控制装置
公开(公告)号：US4145577A
公开(公告)日：1979-03-20
申请号：US828671
申请日：1977-08-29
申请人： Takafumi Kojima , Tatsuru Miyoshi , Takuji Mukaemachi
发明人： Takafumi Kojima , Tatsuru Miyoshi , Takuji Mukaemachi
IPC分类号： H04M3/02 , H04M19/02 , H04M3/04
CPC分类号： H04M19/026
摘要： A ringing control apparatus comprises a bidirectional switching circuit connected in series to a ringing source, which generates an alternating current of a large amplitude, for delivering to a called subscriber the AC signal as an interrupted ringing signal, a phase detector circuit in the form of a zero level detector for detecting the phase of the AC signal generated from the ringing source, and a control circuit for generating a signal for turning on and off the switching circuit in synchronism with the output signal of the phase detector circuit. The delivery of the ringing to the called subscriber is started at a point of time when the ringing voltage comes to a zero level and is stopped at a point of time when the ringing current comes to a zero level, thereby to prevent generation of a surge voltage.
摘要翻译：振铃控制装置包括串联连接到振铃源的双向切换电路，其产生大幅度的交流电流，用于将作为中断振铃信号的AC信号传送给被叫用户，相位检测器电路形式为用于检测从振铃源产生的AC信号的相位的零电平检测器，以及用于产生用于与相位检测器电路的输出信号同步地接通和断开开关电路的信号的控制电路。在振铃电压达到零电平并在振铃电流达到零电平的时间点停止的时间点开始向被叫用户发送振铃，从而防止产生浪涌电压。

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