CIRCUIT DEVICE FOR CHECKING THE CLOSED POSITION OF A FOLDING DOOR

摘要

????? Circuit device for checking the closed position of a folding door In the case of prison cell doors, strong room doors and the doors of safes and strongboxes the problem exists of protecting a switch fitted to the door or its frame and which as a result of the closing movement of the door releases an alarm signal from manipulations by unauthorised persons, for example the emission of a false signal by a prisoner when the cell door is open. A signal switch with roller is detachably fixed to door and a stationary eccentric disc which serves as the switch actuator is detachably fixed to frame . This mechanical switch device is housed in a casing , whose base is welded to door and whose coverlike cap is locked from the inside to casing base by means of a cylindrical lock in casing and is consequently secured against raising therefrom. In the case of an optical switching device a transmitter for infrared alternating light and a receiver with switching transistor are arranged within the door or frame or vice versa. Only when the door is closed is an infrared beam passed through two aligned transmission beam ports in door and frame to receiver , thereby releasing an alarm signal.