| 摘要 |
PURPOSE:To improve the facilitation for the user of a slave device by transmitting the power failure information to the slave device from a master device while a back-up function is working against the power failure. CONSTITUTION:A cordless telephone master device 1 includes a power supply part 3 connected to a commercial power supply, a back-up part 4, a control circuit 5, a data transmission circuit part 6, a radio connection part 7, etc. Meanwhile a cordless telephone slave device 2 contains a battery. When the feeding system is changed to a back-up system from a normal system, the part 3 outputs a power failure information signal to the part 5. Then the part 5 instructs the part 6 to output the power failure information signal to the part 7. Receiving the power failure signal, the part 7 transmits by radio the power failure information signal to the device 2 during the back-up feeding mode. A built-in battery of the device 2 supplies the power to each part regardless of the feeding state of the device 1. So that the device 2 can hear or view the power failure information signal received by radio in a busy mode or a call waiting mode. |
