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Self-testing security sensor for monitoring closure of vault doors and the like

United States Patent

*** EXPIRED ***
May 27, 1997
View the Complete Patent at the US Patent & Trademark Office
Sandia National Laboratories - Visit the Intellectual Property Management and Licensing Website
A self-testing device is provided for a monitoring system for monitoring whether a closure member such as a door or window is closed. The monitoring system includes a switch unit mounted on the frame of the closure member being monitored and including magnetically biased switches connected in one or more electrical monitoring circuits, and a door magnet unit mounted on the closure member being monitored. The door magnet includes one or more permanent magnets that produce a magnetic field which, when the closure member is closed, cause said switches to assume a first state. When the closure member is opened, the switches switch to a second, alarm state. The self-testing device is electrically controllable from a remote location and produces a canceling or diverting magnetic field which simulates the effect of movement of the closure member from the closed position thereof without any actual movement of the member.
Cawthorne; Duane C. (Amarillo, TX)
The United States of America as represented by the United States (Washington, DC)
08/ 520,634
August 29, 1995
The United States Government has rights in this invention pursuant to Contract No. DE-AC04-91AL65030 between Mason & Hanger-Silas Mason Co., Inc. and the United States Department of Energy.