ELECTRIC CIRCUIT FOR A SAFETY DOOR EDGE

• US 3,754,176 A
• Filed: 05/26/1972
• Issued: 08/21/1973
• Est. Priority Date: 05/26/1972
• Status: Expired due to Term

• Current Assignee: Norman K. Miller
• Original Assignee: Norman K. Miller
• Inventors: Miller, Norman K.
• Primary Examiner(s): Dobeck, B.
• Application Number:
  US05/257,311
• Time in Patent Office: 452 Days
• Field of Search: 307/119 318/266 200/61.43
• US Class Current: 318/266
• CPC Class Codes: E05F 15/44 responsive to changes in electrical conductivity
• CPC Class Codes: E05Y 2900/132 Doors

Abstract

For an electrically powered door having a safety edge, an electric circuit including at least a pair of normally spaced conductor strips resiliently deflectable into engagement with each other by an obstruction in the path of door movement, the contact strips being connected in series, and relay means connected in series with the contact strips having normally closed contacts connected in circuit with the door powering means, so that engagement of the strips operates the relay to prevent further powering of the door in its closing direction.

Claims

1. In a safety edge construction for an electrically powered door or the like, an electric circuit comprising at least three resiliently yieldably spaced flexible contact strips defining at least two strip pairs adapted to be deflected into respective successive contact by an obstruction in the path of door movement, conductor means connecting said strips in series with each other across a source of electric supply, and a pair of relays each having its coil connected in a respective strip pair and having contacts in circuit with door powering means, the contacts of one relay connected in the first deflected strip pair being closed when its coil is energized by normal operating circuit through these strips for maintaining the door powering circuit normally enabled, said one relay contacts operating upon contact of said first deflected strip pair to disable the powering circuit, the contacts of the other relay connected in the second deflected strip pair being independent of said one relay contacts and operative to reversely power the door, said other relay contacts being open when its coil is energized by normal operating current through the strips and closed upon contact of said second deflected strip pair to effect reverse powering of the door, whereby contact between said first deflected strip pair shunts said one relay to open its contacts and disable said door powering means, serverance of one of said contact strips precluding the normal operation of said one relay and requiring repair to effect normal operation and contact between said second deflected strip pair shunting said other relay coil to close its contacts and effect reverse powering to the door.

2. An electric circuit according to claim 1, in combination with indicator means in series with said strips indicating the continuity of the strip circuit.

3. An electric circuit according to claim 1, in combination with a manual emergency switch electrically connected to selectively by-pass said one relay contacts and effect manually controlled closing of a door having a defective contact strip, said emergency switch being located within sight of the door to insure a clear path of door movement.

4. An electric circuit according to claim 1, said first mentioned relay having its coil connected across one adjacent pair of said contact strips.

5. An electric circuit according to claim 5, said contact strips comprising two pairs, said one relay having its coil connected between one of said pairs, and said other relay having its coil connected between the other of said pairs.

6. An electric circuit according to claim 5, in combination with first switch means in series with said one relay contacts for selectively operating the door in one direction, and second switch means in parallelism with said other relay contacts for selectively reversing current to operate the door in the other direction.