Non-contact tamper sensing by electronic means

Patent · Tue Aug 17 00:00:00 EDT 1993

OSTI ID:6158601

Gritton, D G

A tamper-sensing tag is described comprising: a tag body adapted to be fixed against movement relative to a surface of an article, a capacitor having at least one variable-capacity section with first and second elements, said first element being positionable relative to said second element at various positions, displaced from each other, said one variable-capacity section having different amounts of capacity when said first element is in its various positions, respectively, relative to said second element, means for generating a first signal which is a function of the amount of capacity of said one variable-capacity section, said first signal having various values distinguishable from each other when said first element is in its various positions, respectively, relative to said second element, one of said first and second elements being fixed against movement relative to said tag body, and the other of said first and second elements being adapted to be fixed against movement relative to said surface of said article and with said first element being in a first position relative to said second element, said tag body and said other of said first and second elements being positionable relative to each other on said article prior to said tag body's being fixed to said article so as to enable said elements to be fixed to said article in said first position relative to each other, means in said tag for generating a second signal having a value unrelated to the amount of capacity of said one variable-capacity section, means in said tag for combining said first and second signals, means in said tag for encrypting said combined signals, means in said tag responsive to external interrogation of said tag for sending from said tag the encrypted combined signals in digital form, and wherein said means for generating said second signal has the function of changing the value of said second signal for each interrogation of said tag.

• Research Organization: DOESC (USDOE Office of Science (SC) (United States))
• DOE Contract Number: W-7405-ENG-48
• Assignee: Dept. of Energy, Washington, DC (United States)
• Patent Number(s): 5,237,307
• Application Number: 07/799,441; PPN: US 7-700441; TRN: 93-017244
• OSTI ID: 6158601
• Resource Relation: Patent File Date: 27 Nov 1991
• Country of Publication: United States
• Language: English

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