Cabinet with tamper detection system and method

Abstract

A cabinet formed of a plurality of panels, includes a tamper detection system that includes an electrical circuit for detecting forming of a hole in a protected region of at least one panels. The electrical circuit includes at least one conductive trace on one of the panels. The conductive trace spans a protected region, wherein the minimum distance from any point in the protected region to the at least one conductive trace does not exceed some defined maximum. An electrical current source provides a current through the conductive trace. A sensor is in electrical communication with the electrical current source to sense a change in current provided to the trace and generate a tamper signal in response thereto.

What is claimed: 
     
         1 . A cabinet comprising:
 a plurality of panels;   an electrical circuit for detecting forming of a hole in a protected region of at least one of said plurality of panels, said electrical circuit comprising:
 at least one conductive trace on at least one of said panels, said conductive trace spanning said protected region of said one of said panels, wherein the minimum distance from any point in said protected region to said at least one conductive trace does not exceed 50 mm; 
 an electrical current source to provide a current through said at least one conductive trace; 
 a sensor in electrical communication with said electrical current source to sense a change in current provided to said at least one conductive trace and generate a tamper signal in response thereto. 
   
     
     
         2 . The cabinet of  claim 1 , wherein said minimum distance from any point in the protected region to said at least one conductive trace does not exceed 5 mm. 
     
     
         3 . The cabinet of  claim 1 , wherein said minimum distance from any point in the protected region to said at least one conductive trace does not exceed 1.25 mm. 
     
     
         4 . The cabinet of  claim 1 , wherein said minimum distance from any point in the protected region to said at least one conductive trace does not exceed 0.5 mm. 
     
     
         5 . The cabinet of  claim 1 , wherein a hole having a radius of at least 50 mm cannot be formed in said protected region without severing said conductive trace. 
     
     
         6 . The cabinet of  claim 1 , wherein the minimum distance from any point in said protected region to another point in said protected region on the opposite side of said at least one conductive trace does not exceed 50 mm. 
     
     
         7 . The cabinet of  claim 1 , wherein said at least one panel is conductive and said sensor is in electrical communication with said electrical at least one of said panels to detect a short between said at least one conductive trace and said at least one of said panels. 
     
     
         8 . The cabinet of  claim 1 , wherein said protected region comprises substantially the entire surface of said one of said panels. 
     
     
         9 . The cabinet of  claim 1 , wherein said protected region is rectangular. 
     
     
         10 . The cabinet of  claim 7 , wherein said conductive trace comprises a series of passes of said conductive trace, each spanning substantially the entire width of said protected region and spaced apart at a pitch of less than 100 mm, such that said conductive trace spans substantially the entire height of said protected region. 
     
     
         11 . The cabinet of  claim 7 , wherein said conductive trace comprises a first plurality of trace elements arranged parallel to one another and spanning the entire height of said protected region. 
     
     
         12 . The cabinet of  claim 10 , wherein said conductive trace comprises a second plurality of trace elements arranged parallel to one another and spanning the entire width of said protected region. 
     
     
         13 . The cabinet of  claim 1 , wherein said change in current results from interruption of said conductive trace. 
     
     
         14 . The cabinet of  claim 1 , wherein said change in current results from electrical interconnection of said conductive trace with one of said panels. 
     
     
         15 . The cabinet of  claim 1 , wherein said sensor comprises an opto-isolator. 
     
     
         16 . The cabinet of  claim 1 , wherein further comprising an isolation circuit to isolate said current source from ground and from a power supply driving a device contained within said cabinet. 
     
     
         17 . The cabinet of  claim 14 , wherein said sensor comprises a latch circuit operable to detect an electrical interconnection of said conductive trace with one of said panels of minimum duration. 
     
     
         18 . The cabinet of  claim 1 , wherein said change in current results from shorting of a load on a transformer. 
     
     
         19 . The cabinet of  claim 1 , wherein said conductive trace is printed on a PVC substrate and attached to said one of said panels using an adhesive foil. 
     
     
         20 . A tamper-detection system for attachment to a panel, comprising:
 a substrate;   at least one conductive trace attached to said substrate, for attachment to a protected region of said panel, wherein the minimum distance from any point in said protected region to said at least one conductive trace does not exceed 50 mm;   an electrical current source to provide a current through said at least one conductive trace;   a sensor in electrical communication with said electrical current source to sense a change in current provided to said at least one conductive trace and generate a tamper signal in response thereto.   
     
     
         21 . A method of detecting tampering with a cabinet, comprising:
 providing a cabinet enclosure having a plurality of panels;   providing a tamper-detection circuit comprising a current source, a conductive trace on a protected region of at least one of said panels, and a current detector;   detecting a change in current provided to said conductive trace;   generating a tamper-condition signal.   
     
     
         22 . The method of  claim 21 , wherein said change in current results from interruption of said conductive trace. 
     
     
         23 . The method of  claim 21 , wherein said change in current results from electrical interconnection of said conductive trace with said enclosure. 
     
     
         24 . The method of  claim 21 , wherein said change in current results from electrical interconnection of said conductive trace with said enclosure for a predetermined minimum duration. 
     
     
         25 . A cabinet comprising:
 a plurality of panels;   an electrical circuit comprising:   at least one conductive trace on a protected region of at least one of said panels, said at least one conductive trace arranged in a pattern, said pattern having a pitch less than 50 mm and spanning substantially the entire surface of said one of said panels;   an electrical current source to provide a current through said at least one conductive trace;   a sensor in electrical communication with said electrical current source to sense a change in current provided to said at least one conductive trace and generate a tamper signal in response thereto.