ELECTRONIC TAMPER EVIDENT SEAL
First Claim
1. An electronic security seal comprising:
- a body;
an elongated electrically conductive shackle;
first and second electrically conductive terminals secured to the body and coupled to the shackle in a shackle locked state wherein the terminals form a complex impedance with the shackle, the impedance manifesting the shackle length between the terminals;
an electrical circuit for measuring the impedance and for indicating a tamper condition; and
a locking arrangement for adjustably locking the shackle to the body.
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Accused Products
Abstract
Disclosed is a reusable locking unit and a one time use electrically conductive molded thermoplastic shackle loaded with carbon black particles and having a linear resistance that is periodically monitored. The locking unit includes an integrated circuit for measuring shackle impedance through terminals capacitively coupled to the shackle. The terminals allow for adjustment of the length of the seal shackle in the locked secured state. The terminals and shackle form an RC network having a complex impedance that manifests the locked adjusted shackle length. Two AC signals at two different frequencies are used to measure impedance, which is compared with an initially determined or continually generated reference impedance to determine a tampered state of the shackle. Temperature compensation is also disclosed. A time stamp is stored for noting the tampering time of occurrence. A battery may be used to operate the circuit internal components and power from the remote transceiver may operate the circuit communication portion. Monitoring may be automatically periodic or activated only upon an external command. LEDs provide visual indication of the seal tamper status.
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Citations
32 Claims
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1. An electronic security seal comprising:
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a body;
an elongated electrically conductive shackle;
first and second electrically conductive terminals secured to the body and coupled to the shackle in a shackle locked state wherein the terminals form a complex impedance with the shackle, the impedance manifesting the shackle length between the terminals;
an electrical circuit for measuring the impedance and for indicating a tamper condition; and
a locking arrangement for adjustably locking the shackle to the body. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. An electronic tamper evident seal comprising:
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a locking unit and an electrically conductive shackle having opposing first and second ends;
the locking unit including first and second spaced electrically conductive terminals, the locking unit for locking the shackle first and second ends thereto, the length of the shackle between the terminals manifesting a first impedance, the terminals for receiving and being electrically coupled to the shackle, at least one of the terminals forming a second impedance with the shackle, the first and second impedances forming a complex impedance;
the locking unit including a circuit for measuring the value of the complex impedance, the locking unit being arranged to allow adjustment of the length of the shackle as the shackle is being locked to the locking unit to thereby adjust the value of the complex impedance which manifests the adjusted shackle length. - View Dependent Claims (24, 25, 26, 27)
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28. An electronic tamper evident security seal comprising:
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a body;
an elongated electrically conductive shackle having opposite first and second ends;
first and second electrically conductive terminals secured to the body for respectively receiving the first and second ends adjacent thereto, the shackle exhibiting a settable length between the terminals for securing an article thereto, the terminals and the shackle length together forming a complex electrical impedance network having a given value manifesting the shackle set length;
an electronic circuit for measuring the impedance value of the electrical network, for comparing the measured value to a reference value and to generate a signal manifesting the compared measured network value for monitoring the integrity of the shackle; and
a locking arrangement for locking the shackle to the body with the shackle electrically coupled to the terminals, the terminals and locking arrangement for permitting the setting of the shackle length according to tightly secure the shackle to an article. - View Dependent Claims (29, 30, 31, 32)
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Specification