| 摘要 |
PURPOSE:To remove restrictions on the use accompanied with feeding of commercial power by reducing the power in the transmission part or the reception part of a codec at the time of operating a speaker amplifier to reduce the power consumption of the whole of a digital telephone. CONSTITUTION:A control circuit 8 of a digital telephone circuit monitors turning-on/off of a hook switch 6, a speaker reception switch 9, and a dial switch 7, and the normal speaking state using a handset is set if the switch 6 is turned on and switches 7 and 9 are turned off. The off-hook dialing state is set if switches 6 and 7 are turned on and the switch 9 is turned off, and the speaker reception state or the on-hook dialing state is set if the switch 9 is turned on and the switch 7 is turned off or on. The power in a codec transmission part 2a or a reception part 28 is reduced by an AND gate 15, an analog switch 12, and an interface circuit 1 or the like at the time of operating a speaker amplifier 10, thus reducing the power consumption of the whole of the telephone. |
