Safety door edge

Claim 1

A fail-safe door safety closing system including a door frame, a door movably mounted in said door frame and movable into an open and a closed position, a control means to generate a control signal, a door operating means having an independent first power source to open said door upon receiving a control signal from said control means, said door having a safety edge means which is movable against said door frame in said closed position, said edge means including first and second conductive ribbon means, each of said ribbon means having first and second terminals separated by a length of conductive ribbon, said ribbons being normally separated and contacting each other upon an edge striking an obstruction, an active circuit comprising second power source means to provide electrical power to said active circuit and a relay means having a coil with first and second terminals, relay contacts and a movable member which closes said relay contacts when the relay is energized and opens said relay contacts when the relay is de-energized, the first relay terminal being connected to the first terminal of the first ribbon means and the second relay terminal being connected to the first terminal of the second ribbon means, said second terminals of both said ribbon means being connected in series with said second power source, said relay contacts when closed operating said control means and starting the operation of said door operating means to close the door, said contacts when open de-energizing said control means so that said door operating means opens said door, wherein said relay coil is shorted by the contacting of said ribbons and said relay is de-energized upon failure of the active circuit, thereby opening said door upon active circuit failure.