Tamper-proof device for detecting opening and closing of a secure container

• US 5,111,184 A
• Filed: 02/25/1991
• Issued: 05/05/1992
• Est. Priority Date: 02/25/1991
• Status: Expired due to Fees

• Current Assignee: Aerojet-General Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Atlantic Research Corporation (L3Harris Technologies, Inc.)
• Inventors: Arneson, Michael R., LaRocca, Guy P., Heaton, Harley L.
• Primary Examiner(s): Ng, Jin F.
• Assistant Examiner(s): Oda, Christine K.
• Application Number:
  US07/659,619
• Time in Patent Office: 435 Days
• Field of Search: 250/227.14, 250/227.16, 250/231.10, 250/231.19, 340/540, 340/542, 340/550, 340/552, 340/553, 340/555, 340/545, 340/556, 340/557
• US Class Current: 340/542
• CPC Class Codes: G08B 13/126 for a housing, e.g. a box, a safe, or a room
• CPC Class Codes: G08B 13/186 using light guides, e.g. optical fibres

Abstract

A tamper-proof device for detecting opening and closing events of a secure container is characterized by a fiber optic cable having a first portion connected with a fixed member of the container and a second portion connected with a movable locking member of the container so that the cable is bent or flexed when the container locking member is moved between open and closed positions. Light pulses are transmitted through the cable and variations in the pulses resulting from bending of the cable are detected to indicate opening and closing of the container.

Claims

1. A tamper-proof device for detecting opening and closing events of a secure container, comprising

(a) a fiber optic cable having a first portion connected with a fixed member of the container and a second portion connected with a movable locking member of the container, whereby said cable is deflected when the container locking member is moved between open and closed positions;

(b) an optical source connected with one end of said cable for delivering a light signal to said cable; and

(c) optical detector means connected with the other end of said cable for sensing variations in the light signal transmitted through the cable as a result of microbend losses due to deflection of said cable, whereby each opening and closing event of the container is detected.

2. A device as defined in claim 1, wherein said optical source includes means for producing a pulsed light signal, thereby to conserve power.

3. A device as defined in claim 2, wherein said pulsed light signal comprises two optical frequencies which are beat together.

4. A device as defined in claim 1, and further comprising microcontroller means connected with said detector means, said microcontroller means being operable in response to an event.

5. A device as defined in claim 4, wherein said microcontroller means includes timing means for timing each opening and closing event.

6. A device as defined in claim 5, wherein said microcontroller means further includes memory means for storing the occurrence of events and the times thereof.

7. A device as defined in claim 6, and further comprising display means connected with said microcontroller mean for indicating events.

8. A device as defined in claim 7, wherein said display means comprises a liquid crystal diode.

9. A device as defined in claim 7, and further comprising a fiber optic modem connected with said microcontroller for communicating therewith.

10. A device as defined in claim 9, and further comprising an interface device connected with said modem via a fiber optic cable assembly for reading data from said memory means, for providing a password for access to said microcontroller, and for resetting said timing means.

11. A device as defined in claim 2, wherein said optical source comprises light emitting diode.

12. A device as defined in claim 2, wherein said optical source comprises a laser.