| 摘要 |
PROBLEM TO BE SOLVED: To provide a doorphone system that can save energy by reducing consumption of commercial power in a standby state. SOLUTION: In the standby state, a solar battery 59 and a capacitor 60 supply electric charges to a call circuit 53 of a doorphone slave unit 1. When the circuit 53 is activated, the charges stored in the capacitor are supplied to a switch element 67 through a connection line 55 and a changeover circuit 56, and an output of the switch element 67 is applied to a start control circuit 66 as an ON signal. A switch circuit 64 switched on by the start control circuit supplies a commercial power supply to an AC power supply circuit 65, the AC power supply supplies DC power to a multiplexer circuit 63, a control circuit 69, a transmission reception amplifier 72, and a call tone output circuit 70, the control circuit receiving the power outputs a call tone to the call tone output circuit, the changeover circuit is switched to supply the power and a speech signal to a transmission/reception amplifier 51 of a doorphone slave unit via a multiplexer circuit 54 to bring the doorphone slave unit and a doorphone master unit into a speech state. |
