| 摘要 |
An electric lock (61) and a surveillant control device (60) with an electric source circuit (15) are electrically connected by two wires (12). After actuation of a solenoid (4) in the electric lock (61), the current passed through the surveillant control device (60) decreases by the changing-over of switch (6) linked with the actuation of the solenoid. The electric source circuit (15) is adapted to have so low impedance as to supply current to the electric lock (61) only during on- or off-operation of the lock, but then it has usually so high impedance as to supply the check current with alternately converting polarities to the electric lock (61). In the wire circuit there are provided a door switch (10) responsive to the operation of the door and current checking means, which means detects the circuit current for exercising a supervision over the states of opening or closing the door and turning on or off the lock. |
