| 摘要 |
PURPOSE:To simplify the constitution of the circuits for control including the main unit by performing the timing for multiplication of all control signals via the same timing pulse. CONSTITUTION:The key telephone equipment comprises the follwing component units: main wire 1 and 2; main wire circuit 3 and 4; talking and calling crosspoint 5 and 8; extension circuit 6; extension and main wire calling circuit 7 and 9; handsets 13-15; speakers 16-18; key telephone sets 19-21; main device 22; takling and calling voice transmission lines 23-25 and 26-28; up and down control signal transmission lines 29-31 and 35-37; and others. The timing for multiplication is allotted in common to each main wire and extension regardless of the up or down control signal, so the processing is possible in the same type for both modulation and demodulaton of multiplication. Thus, the key telephone equipment as a whole can share the timing. As a result, the control circuit can be simplified not only for key telephone sets 19-21 but for main device 22. |
