| 摘要 |
PROBLEM TO BE SOLVED: To provide a communication device capable of automatically activating a modem unit when a ring signal is transmitted from an opposite side even if the modem unit is turned off, without constantly monitoring the connection of a telephone line to the modem unit.SOLUTION: A first capacitor 70 and a second capacitor 71 each only let an AC voltage component of a ring signal transmitted from an opposite side pass through but not let a constantly-applied DC voltage component pass through. Electric potential difference of the AC voltage component that has passed through is converted into DC voltage, which is in turn supplied to a modem unit 40. Then, even if the modem unit 40 is turned off, the modem unit 40 is automatically activated when a ring signal is transmitted from an opposite side.SELECTED DRAWING: Figure 1 |
