To prevent damage to an automatic door by a criminal person by utilizing an electromagnetic lock device for locking the automatic door, directly sensing moving in an opening direction of the door in a crime prevention mode by a limit switch provided in the electromagnetic lock device, and operating a warning/threatening device instantaneously even in the slight movement of the door.
The electromagnetic lock device includes an electromagnet and an attraction plate to be attracted to the electromagnet, and locks the automatic door through the electromagnet and the attraction plate, and the electromagnet and/or the attraction plate is fixed to a door of an automatic door through an attaching metal fitting. The electromagnet or the attraction plate is maintained in the state of being connected to the attaching metal fitting through an elastic member when locked, and the electromagnet or the attraction plate is separated from the attaching metal fitting opposing the elastic member when the door is moved in an opening direction in a crime prevention mode, the limit switch is provided to be turned ON when the electromagnet or the attraction plate and the attaching metal fitting are separated, and the warning/threatening device is provided to be operated by ON signals of the limit switch.
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