| 摘要 |
PURPOSE:To make a battery power source small-sized, and to stabilize an operation at the time of power failure by providing a processor for stopping the operation in accordance with generation of the power failure, deciding a state of each key telephone set in accordance with recovery of the power failure, and updating the contents of a memory. CONSTITUTION:When a commercial power source is cut off, a processor CPU stores power failure information in a variable memory RAM by a power failure detecting circuit, and thereafter, turns off the power source and stops the operation. When the power failure is recovered, the state of each telephone set ST1-ST16 before the power failure is derived in accordance with the contents of the RAM which has held the storage even in the course of the power failure by a battery power source. By this state, the state of power failure calling relays L1-L5, and the state of a hook switch of each telephone set ST1-ST16, the state of each telephone set ST1-ST16 is decided separately, and the contents of the RAM are updated in accordance with said state. In this way, by turning off the power source of the CPU at the time of power failure, a battery power source in case of the power failure can be converted to a small capacity. |
